阅读说明：本技术 具有安全闭锁/挂牌部件的危险场所合规电路保护装置、系统和方法 (Hazardous location compliance circuit protection device, system and method with safety lockout/tagout feature ) 是由 J·M·马纳汉 A·莱杰伍德 A·巴特勒 G·得卡尔 E·洛本纳 于 2019-12-26 设计创作，主要内容包括：本发明公开了危险场所合规固态电路保护装置,该危险场所合规固态电路保护装置包括安全闭锁部件,该安全闭锁部件确保断路,作为负责人员完成电力系统维护保养任务的保障。该安全闭锁部件可包括与物理锁元件接合的机械闭锁部件、通过固态断路器装置的控件实现的电气闭锁部件以及它们的组合。可向负责人员提供以下视觉装置反馈和确认：已成功激活该闭锁部件,以及已成功去激活该闭锁部件以重新连接并恢复负载侧电路的操作。(The invention discloses a hazardous location compliance solid state circuit protection device which comprises a safety locking part, wherein the safety locking part ensures the open circuit and is used as a guarantee for a responsible person to complete the maintenance task of a power system. The safety lockout feature may include a mechanical lockout feature that engages with a physical lock element, an electrical lockout feature implemented by a control of the solid state circuit breaker device, and combinations thereof. The following visual device feedback and confirmation may be provided to the responsible person: the latch member has been successfully activated and has been successfully deactivated to reconnect and restore operation of the load side circuit.)

1. A compliance switch device for use in hazardous locations, the compliance switch device comprising:

an ignition-resistant housing;

a line side terminal and a load side terminal coupled to the housing;

a bus structure in the housing and including at least one solid state switching element operable in an arcless manner to connect and disconnect the load side terminal to the line side terminal;

an on/off input selector for changing a state of the at least one solid state switching element;

a controller monitoring a state of the on/off input selector and responsive to a change in state of a lockout input selector, the controller configured to activate a safety lockout condition that disables the on/off input selector and prevents a change in state of the on/off input selector;

the switching device is thus compliant for use in explosive environments without the need for a separately provided explosion proof housing.

2. The switching device of claim 1, wherein the controller is further configured to confirm a change in state of the at least one solid state switching element and provide confirmation of the changed state to a user.

3. The switching device of claim 1, wherein the on/off input selector is a mechanical input selector.

4. The switching device of claim 3, wherein the on/off input selector is a mechanical toggle switch.

5. A switch arrangement according to claim 3, wherein the mechanical toggle switch is fixable in an open position via a mechanical lock element.

6. The switching device of claim 5, wherein the mechanical lock element is a padlock.

7. The switching device of claim 1, wherein the on/off input selector is incorporated in an electronic display.

8. The switching device of claim 1, wherein the controller is configured to deactivate the safety lockout condition when a user provides a predetermined passcode.

9. The switching device of claim 1, further comprising a detector that senses the presence or absence of a mechanical lock element for the safety lockout.

10. The switching device of claim 9, wherein the detector is configured to sense a padlock handle.

11. A switching apparatus according to claim 1, wherein a plurality of different types of safety blocking means are provided.

12. The switching device of claim 11, wherein the plurality of different types of safety lockout features are operable in combination to effect a multi-step lockout procedure.

13. The switch device of claim 1, wherein the plurality of different types of security lockout components include a mechanical toggle switch and lock opening, a padlock and a detector that senses the presence of the padlock, and a multifunction display.

14. The switching device of claim 1, further comprising at least one mechanical switch contact in the bus structure, and the housing comprises a sealed inner enclosure that houses the at least one mechanical switch contact, thereby preventing the switch contact from becoming an ignition source in the explosive environment.

15. The switching device of claim 1, wherein the at least one solid state switching element is encapsulated.

16. The switching device of claim 1, wherein the device is configured as a solid state overcurrent protection device.

17. The switching device of claim 1, wherein the device is configured as a hybrid overcurrent protection device.

18. The switching device of claim 1, wherein the housing is electrically grounded.

19. The switching device of claim 1, wherein the housing exhibits antistatic properties.

20. The switchgear of claim 1 wherein the housing is chemically resistant in the hazardous location.

The field of the invention relates generally to circuit protection devices and, more particularly, to a hazardous environment compliant circuit protection device including enhanced safety lockout features for completing power system maintenance tasks.

To meet the needs of power systems that provide power to various electrical loads, there are a variety of different types of circuit protection devices. For example, various devices and assemblies are known that provide a circuit interrupting function between a power circuit and an electrical load. With such devices in possession, output power may be selectively switched from a power source by such devices, either manually or automatically, to facilitate maintenance of the power system and to address electrical fault conditions. Circuit breaker apparatus and fusible disconnect switch apparatus are two well-known types of apparatus that each provide different capabilities for responding to overcurrent and electrical fault conditions and electrically isolate load-side electrical equipment from line-side power circuitry, thereby protecting the load-side equipment and circuitry from other damaging overcurrent conditions in the power system.

While known circuit protector interrupting devices can be used to meet the needs of many electrical systems, they are still disadvantageous in some respects for certain types of electrical systems and applications in which the circuit protector is located in a hazardous location. Thus, existing circuit breaker breaking devices have not yet fully met the market needs. Improvements are therefore needed.

Background

Drawings

Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

Fig. 1 is a perspective view of a compliant hazardous location arc-free circuit protection device according to a first exemplary embodiment of the present invention.

Fig. 2 is a simplified schematic diagram of the circuit protection device shown in fig. 1 in an exemplary solid state configuration.

Fig. 3 is a block diagram of the circuit protection device shown in fig. 1 and 2.

Fig. 4 is a front view of the circuit protection device of fig. 1-3, showing an exemplary safety lockout/tagout feature of the circuit protection device.

Fig. 5 is an end view of the circuit protection device of fig. 4 in an open state showing the safety lockout/tagout member engaged.

Fig. 6 is an end view of the circuit protection device of fig. 4 in a connected state with the exemplary safety lockout/tagout member disengaged.

FIG. 7 is an exemplary algorithmic flow chart of a security lockout activation and deactivation sequence for the device of FIGS. 4-6.

Fig. 8 is a perspective view of a compliant hazardous location arc-free circuit protection device according to a second exemplary embodiment of the present invention.

Fig. 9 is a simplified schematic diagram of the circuit protection device shown in fig. 8 in an exemplary hybrid configuration.

Fig. 10 is a block diagram of the circuit protection device shown in fig. 8 and 9.

Fig. 11 schematically illustrates thermal management features of the circuit protection devices shown in fig. 8-10.

Fig. 12 illustrates an exemplary power distribution panel including compliant explosion-prone site circuit protection devices.

Detailed Description

To maximize the understanding of the inventive concepts described herein, the following sets forth a discussion of the prior art as it relates to problems caused by hazardous locations, followed by a description of exemplary embodiments of devices, systems, and methods that address such problems and satisfy a long-standing, unmet need in the art.

I. Description of the Prior Art

Power systems sometimes operate in hazardous environments with the risk of explosion due to ignition of ambient gas or vapor dust, fibers or fly ash. Such hazardous environments may only occur, for example, in oil refineries, petrochemical plants, grain silos, wastewater and/or treatment facilities, and other industrial facilities, where the surrounding environment creates unstable conditions that increase the risk of fire or explosion. The temporary or persistent presence of combustible gases, combustible vapors or combustible dust or other combustible substances in the air presents a significant challenge to the overall safe and reliable operation of these facilities, including but not limited to the safe operation of the power system itself, and in some cases, with conventional circuit protection devices, ignition sources may be generated during normal operation and during electrical faults. Accordingly, many standards have been promulgated regarding the use of electrical products in explosive environments to improve safety in hazardous locations, based on the probability of an assessment of the risk of explosion or fire.

For example, Underwriter's Laboratories, UL 1203 specifies the standards for explosion-proof, dust-burning-proof electrical equipment used in hazardous locations. Presently, explosion and dust proof ignition enclosures exist that can be used to enclose or contain electrical products, including, but not necessarily limited to, circuit protection devices that are not themselves explosion and dust proof ignition. By incorporating an appropriate explosion-proof and dust-proof ignition enclosure, electrical equipment manufacturers can obtain UL certification, which is an important aspect of the manufacturers' ability to successfully market products to north america or any other market that accepts UL standard UL 1203, proving that it complies with a rating standard applicable to hazardous locations.

The National Electrical Code (NEC) generally classifies hazardous locations by class and segment. Class I sites are those sites in which flammable vapors and gases may be present. Class II sites are those where combustible dust is present. Class III sites are those sites that become hazardous due to the presence of ignitable fibers or fly-away. Stage I, section 1, covers sites where combustible gases or vapors may be present under normal operating conditions, under frequent repair or maintenance operations, or where a failure or faulty operation of a process equipment may also result in a simultaneous failure of electrical equipment. There is a greater risk of explosion in section 1 than in section 2, for example, where combustible gases or vapours are normally handled in closed systems, confined within suitable enclosures, or are normally prevented by active mechanical ventilation.

The International Electrotechnical Commission (IEC) also classifies hazardous locations as zone 0, zone 1, or zone 2, which represents locations that carry combustible gases or vapors in air in amounts sufficient to produce explosive or flammable mixtures. By zone 0 site is meant a site where combustible gases or vapors of ignitable concentration are present continuously or over time, as defined by IEC. The zone 1 site refers to a site where combustible gas or vapor having an ignitable concentration may or may often be present due to a repair or maintenance operation, or due to leakage or possible release of combustible gas or vapor having an ignitable concentration, or a site adjacent to the zone 0 site where vapor having an ignitable concentration may be delivered from the zone 0 site.

Since electrical devices (such as those described below) may in some cases be ignition sources, it is common to provide explosion-proof, flame-retardant or ignition-proof housings in the field of 1 or 2 of NEC and/or in the field of 1 or 2 of IEC to accommodate electrical devices that otherwise pose an ignition risk. As used herein, the term "explosion proof" or "flame retardant" refers to an internally explosive enclosure designed to contain a designated combustible vapor-air mixture. Furthermore, the explosion-proof or fire-proof enclosure must operate at a safe temperature with respect to the ambient air.

Conventional circuit breaker devices, various types of switching devices and contactor devices are known that include input terminals connectable to a power source or line side circuit, output terminals connectable to one or more electrical loads, and pairs of mechanical switch contacts between respective input and output terminals. Each pair of mechanical switch contacts typically includes a stationary contact and a movable contact connected to an actuator element that displaces the movable contact toward and away from the stationary contact along a predetermined path of motion to connect and disconnect a circuit path through the device to electrically connect or disconnect the input and output terminals. The apparatus is for isolating one or more electrical loads connected to the output terminals from a power source connected to the input terminals when the switch contacts are open. The actuator element in the above-described mechanical switching device may be automatically moved for circuit protection purposes to open the mechanical switch contacts in response to an overcurrent or fault condition in the line-side circuit and electrically isolate the electrical load from the electrical fault condition to prevent them from being damaged, or the actuator element may be manually movable to electrically isolate the electrical load from the line-side power supply to conserve energy, maintenance loads, etc.

Circuit breakers and fusible disconnect switch devices are two well-known types of devices that each provide different types of disconnect functions and circuit protection through mechanical switch contacts. IEC includes the following relevant definitions:

2.2.11

circuit breaker

Mechanical switching devices capable of switching on, carrying and switching off current under normal circuit conditions, and also capable of switching on, carrying and switching off current for a prescribed time under prescribed abnormal circuit conditions (such as short-circuiting) [441-14-20]

2.2.9

Switch (mechanical)

Mechanical switching devices capable of switching current on, off, and on under normal circuit conditions, which may include prescribed operational overload conditions, and also capable of carrying current for a prescribed time under prescribed abnormal circuit conditions (such as short-circuiting) [441-14-10]

Note that the switch can turn on but cannot turn off the short circuit current.

2.2.1

Switching device

Devices designed to switch current on or off in one or more circuits [441-14-01]

Note that the switching device may perform one or both of these operations.

As can be seen from the above definitions, the circuit breaker defined in IEC 2.2.11 and the mechanical switch defined in IEC 2.2.9 differ in their ability to mechanically respond to abnormal circuit conditions. In particular, the circuit breaker defined in IEC 2.2.11 may mechanically break a short circuit condition, whereas the mechanical switch defined in IEC 2.2.9 cannot break a short circuit condition. Thus, electrical fuses are sometimes used in conjunction with the mechanical switch of IEC 2.2.9 to implement fusible disconnect switches that can respond to a short circuit condition by operation of the fuse (i.e., opening of the fuse) rather than operation of the mechanical switch contacts.

In either of the IEC 2.2.11 and IEC 2.2.9 devices, automatic circuit protection may sometimes be provided only by structural design and calibration of the circuit breaker structure or the fuse element structure in the fuse, as long as each achieves a predetermined time-current characteristic before the circuit is opened. NEC has defined these two basic types of overcurrent protection devices (OCPD) as follows:

a fuse: an overcurrent protection device has a fusible member which is heated and fused by the passage of an overcurrent to open a circuit.

A circuit breaker: a device designed to open and close an electrical circuit in a non-automatic manner and to automatically open the circuit without damaging itself when a predetermined overcurrent is correctly applied within its rating.

NEC also requires that the circuit be provided with a circuit interrupting device, defined as a device or group of devices, or other device that can disconnect the circuit conductor from the power supply of the circuit conductor. Since fuses are designed to open only when subjected to overcurrent, they are often used in conjunction with a separate circuit interrupting device (typically some form of circuit breaker) (NEC article 240 requires this in many cases). Since the circuit breaker is designed to open and close under manual operation and in response to an overcurrent, a separate circuit breaking device is not required.

In some types of circuit protection devices, automatic circuit protection may be achieved by electrical sensors included in the device to monitor actual circuit conditions, and in response to predetermined circuit conditions detected by the sensors, an electromechanical trip feature may be actuated to automatically open the movable contact in response to detected overcurrent conditions (including overload and short circuit conditions). Once tripped, the circuit breaker can be reset or reclosed through the switch contacts to restore the affected circuit, since the circuit breaker is designed to open the circuit without damaging itself, while the fuse opens the circuit through internal degradation of the fuse element that renders the fuse element no longer able to carry current. Therefore, the fuse must be replaced after disconnection to restore the affected circuit. In some cases, a combination of circuit breakers and fuses is also desirable and selectively coordinated to extend the range of overcurrent conditions that can be addressed and improve response times.

In contrast to the circuit protection devices described above, the "switching devices" of IEC 2.2.1 defined above relate only to switching on and off current, and not to switching on or off overcurrent conditions (i.e. overload conditions or short circuit conditions). The "switching device" of IEC 2.2.1 thus provides a circuit breaking function, but not a circuit protection function. IEC 2.2.1 also does not require mechanical switching devices at all, but if a switching device that is not a circuit breaker device actually comprises mechanical switching contacts, it may still present an ignition risk when located in a hazardous environment.

More specifically, the operation of mechanical switch contacts for making or breaking an energized circuit, whether manually actuated by a user under normal circuit conditions or automatically actuated under abnormal circuit conditions, can create a source of ignition in a hazardous environment. In particular, arcing between the switch contacts tends to result when the movable contact is mechanically moved away from the stationary contact (i.e., from the closed position to the open position). A similar arcing may occur when the movable contact moves back toward the stationary contact to reclose the device. If such arcing between the switch contacts is achieved in the presence of flammable gases, vapors or substances, the arcing may ignite the gases, vapors or substances. While mechanical switching contacts are typically enclosed in a housing provided with conventional circuit breakers or other mechanical switching devices and additional enclosures typically used with electrical distribution panels or motor control centers and the like, such housings and enclosures are typically insufficient to isolate the arc from ignitable airborne elements. To this end, known devices comprising mechanical switch contacts are typically located in a separate explosion proof enclosure and then housed in an environmental enclosure, or in a switching system (i.e., switchboard) that can then be installed in a single large explosion proof enclosure, without the need for a separate explosion proof enclosure for switches disposed within 1 segment of the NEC to provide the necessary protection.

In the above described arrangement, the circuit breaker, although mechanically breaking the short circuit condition, experiences the most intense arcing condition and therefore has the greatest potential to ignite flammable gases, vapors or substances in the hazardous location in terms of raw energy and temperature. Given that many industrial power systems and loads operate at relatively high voltages and high currents, the arc energy and temperature under lower current overload conditions and normal conditions are also quite large and quite high, thus posing an ignition risk. Generally, the ignition energy caused by fault energy is related to the magnitude of the current being interrupted, so the greater the current being interrupted, the greater the likelihood and severity of arcing. For example, from an arc discharge perspective, an interruption of 65kA IC is much more significant and therefore more dangerous than an interruption of 10kA IC.

Available explosion, fire or ignition resistant enclosures effectively operate mechanical switchgear safely in section 1 or 2 sites of NEC or in section 1 or 2 sites of IEC, but typically incur additional costs, occupy valuable space in the power system, and impose a certain burden on installation and maintenance of the power system over time. Accessing the circuit interrupting devices within the flameproof housing typically requires time consuming removal of multiple fasteners and, after any maintenance procedures are completed, all of the fasteners must be properly replaced to ensure the desired safety of the flameproof housing. During a maintenance procedure, the area in which the circuit interrupting device is located is typically shut down (i.e., disconnected), while the associated load side process is stopped to ensure safety during the maintenance procedure. From an industrial facility perspective, such downtime is costly and it is important to limit or shorten the downtime. Thus, in some cases, it would be desirable if an explosion proof enclosure could be eliminated at the 1 st site of the NEC while still providing a safety shut down function in a hazardous environment. For this reason, circuit protection devices designed to reduce the risk of ignition are required, but currently such devices are not generally available.

Solid state circuit interrupting devices are known which provide the required interrupting function through semiconductor switches or semiconductor devices such as, but not limited to, Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and other known components which operate electrically in a known manner to block current flow through the device and thereby electrically isolate line side circuitry from load side circuitry in response to predetermined circuit conditions without the use of mechanical switch contacts. Such solid state switches may be implemented in circuit breaker devices or used in combination with fuses to address electrical fault conditions in an automated manner.

The solid state switch advantageously eliminates arcing associated with displacement of the mechanical switch contacts as described above, but still creates a possible source of ignition by heat generated by the solid state switch in use. Even if arcing does not occur during switching operation of the device, depending on the type and concentration of combustible elements in the hazardous location, the surface temperature of the solid state switching device may rise to a point where auto-ignition occurs due to the flash point temperature of certain gases or ignitable substances in the hazardous location.

The connection terminals of solid state switching devices may also create reliability issues and possible ignition sources when used in a segment 1 or 2 site of NEC or a zone 1 or 2 site of IEC. More specifically, the terminals may tend to loosen over time when subjected to thermal cycling or vibration. Under certain operating conditions, loose terminal connections can lead to overheating and possible sources of ignition at the terminal field, if not arcing. Poor quality terminal connections can also cause overheating of the conductor structures (sometimes referred to as busses) in the device, creating further ignition problems in hazardous locations. Thus, the use of only known solid state switching devices (without other devices) does not ensure adequate safety in hazardous locations if an explosion proof enclosure is not supplementarily used in the 1 st or 2 nd site of NEC or the 1 st or 2 nd site of IEC.

So-called hybrid breaking devices are also known, which comprise a semiconductor switch or a combination of a semiconductor device and a mechanical switch contact. Such hybrid devices may also be implemented in circuit breaker devices or used in combination with fuses to address electrical fault conditions in an automated manner. From the point of view of possible ignition sources in hazardous locations, hybrid circuit-breaking devices produce a mixture of the above-mentioned problems and do not ensure sufficient safety if the flameproof housing is not used supplementarily in the field of 1 or 2 of NEC or in the field of 1 or 2 of IEC.

Inventive arc-free devices, systems and methods for hazardous location compliance.

Described herein are exemplary embodiments of circuit protection devices that overcome the above-described problems and provide an enhanced degree of safety for compliance with applicable standards in either a segment 1 or 2 site of NEC or a zone 1 or 2 site of IEC without necessarily requiring a separately provided explosion-, fire-, or ignition-proof enclosure. Thus, by eliminating a separately provided explosion, fire, or ignition resistant enclosure, the example circuit protection devices described herein may be implemented in an electrical power system, not only reducing costs, but also saving valuable space in a distribution panel, control center, or the like. The example circuit protection devices described herein may be provided in a modular and configurable system that facilitates more economical installation, maintenance, and supervision of power systems. Some of the various aspects of the method will be discussed explicitly and other parts will become apparent from the following description.

In a first aspect, an exemplary circuit protection device may be implemented in the form of a solid state circuit protection device having arcless operation in a procedure to switch the device to connect or disconnect a load side circuit through a solid state switching device, in combination with enhanced features to address possible sources of ignition at the connection terminals, and/or including thermal management features to address possible overheating of conductive elements built into the solid state switching device. Thus, when implemented in the form of a solid state circuit breaker device, such solid state circuit breakers, unlike conventional circuit breakers, comply with hazardous site standards applicable to either the 1 st or 2 nd site of NEC or the 1 st or 2 nd site of IEC, thus making conventional explosion, fire or ignition proof enclosures removable for certain applications.

In a second aspect, an exemplary hazardous location compliance solid state circuit breaker device may be provided with a safe lockout/tagout mode that ensures disconnection by the solid state circuit breaker device as a safeguard for responsible personnel to complete power system maintenance tasks. In various embodiments, the secure lockout/tagout mode may be characterized by a mechanical lockout that engages with a physical lock element, an electrical lockout that is implemented by an electronic control of the solid state circuit breaker device, and combinations thereof. The following visual device feedback and confirmation may be provided to the person: the lockout condition has been successfully activated to open the load side circuit so that the worker can safely continue to perform applicable maintenance or service procedures on the load side of the device in a safe manner. The following visual feedback and confirmation may also be provided to the person: the lockout condition has been successfully deactivated to complete the listing process and reconnect and restore operation of the load side circuit.

In a third aspect, the hybrid circuit protection device may be implemented in the form of a combination of solid state switching devices and mechanical switching devices, and may also incorporate enhanced features to isolate the arc between the mechanical switch contacts from the surrounding environment to prevent ignition, as well as to address a possible source of ignition at the connection terminals and/or include thermal management features to avoid possible overheating of conductors in the hybrid device. Thus, unlike conventional hybrid circuit protection devices, such hybrid circuit protection devices comply with hazardous location standards applicable to either the 1 st or 2 nd location of NEC or the 1 st or 2 nd location of IEC, and allow conventional explosion proof enclosures to be removed for certain applications.

In a fourth aspect, an exemplary hazardous location compliance hybrid circuit protection device may be provided with a safety lockout/tagout mode that ensures disconnection by the hybrid circuit protection device as a safeguard for responsible personnel to complete power system maintenance tasks. In various embodiments, the safety lockout mode may be characterized by a mechanical lockout feature that engages with a physical lock element, an electrical lockout feature implemented by a control of the solid state circuit breaker device, and combinations thereof. The following visual device feedback and confirmation may be provided to the person: the lockout condition has been successfully activated to open the load side circuit so that the worker can safely continue to perform applicable maintenance or service procedures on the load side of the device in a safe manner. The following visual feedback and confirmation may also be provided to the person: the lockout condition has been successfully deactivated to complete the listing process and reconnect and restore operation of the load side circuit.

Although the following discussion is made in the context of circuit breaker devices, the inventive concepts below are not necessarily limited to circuit breaker devices, but may be broadly applied to other types of devices, examples of which are discussed above, which create similar problems from the standpoint of ignition problems in hazardous locations. Also, although the inventive concepts are described in the context of hazardous locations (such as a 1 or 2 segment location of a NEC or a 1 or 2 segment location of an IEC), the benefits of the described concepts are not necessarily limited to a 1 or 2 segment location of a NEC or a 1 or 2 segment location of an IEC, but may be more broadly applied to other types of hazardous environments, and in some aspects may be advantageously provided for non-hazardous locations as desired.

FIG. 1 is a perspective view of a compliant hazardous environment circuit protection device 100 according to a first exemplary embodiment of the present invention. The circuit protection device 100 includes a housing 102 having opposing longitudinal sides 104, 106 and opposing lateral sides 108, 110 disposed generally orthogonally with respect to the longitudinal sides 104, 106. The housing 102 also includes a front side 112 and a rear side 114, and the front side 112 may include an optional digital display 116 that serves as a user interface for the device 100. As shown, the display 116 visually indicates the voltage, current, power, and energy readings to the device 100 and to a person near the display 116.

The housing 102 of the apparatus 100 is made of strategically selected or otherwise customized materials to withstand all possible electrical operating conditions, particularly all possible electrical fault conditions, including concurrent fault conditions that may result from a protected power system in a section 1 or 2 site of a NEC or a section 1 or 2 site of an IEC.

To comply in the field of NEC, or IEC, zone 1 or zone 2, the housing structure and housing materials must also be further formulated to provide sufficient strength to withstand the shock and impact forces that may occur in an explosive environment, as well as chemical resistance to withstand exposure to chemicals in an explosive environment that may otherwise adversely affect the integrity of the device 100. As used herein, "chemical resistance" refers to the strength of the shell material to prevent chemical attack or solvent reaction. Chemical resistance in the housing 102 is in contrast to chemical reactivity, which may cause undesirable chemical effects when the housing 102 is exposed to certain chemicals and/or may undesirably generate heat and raise the temperature of the housing 102. Chemical resistance, by virtue of having little or no reactivity with a specified chemical, relates to the resistance of the housing 102 to corrosive or caustic substances in the environment, including but not limited to airborne gases and vapors. For the apparatus 100, chemical resistance is important for all materials described herein and structures that contribute to hazardous site compliance.

UL 1203 defines a chemical test that may be applied to determine if any formulation of candidate materials for housing 102 is chemically resistant to explosive environmental sites. In particular, the UL 1203 chemical test requires that the sample housing be made of a formulation of candidate materials in a desired housing configuration and that the sample housing be exposed for a predetermined period of time to saturated vapors in air containing a variety of specified chemicals. The specified chemicals used in the UL 1203 chemical test include acetic acid, acetone, ammonium hydroxide, ASTM reference fuel C, diethyl ether, ethyl acetate, ethylene dichloride, furfural, n-hexane, methyl ethyl ketone, methanol, 2-nitropropane, and toluene. Different sample housings are exposed to each chemical for a predetermined period of time, and after exposure to each chemical, the sample housings are inspected to ensure that the sample's housing structure is not damaged or shows signs of deterioration via, for example, discoloration, expansion, shrinkage, cracking, leaching, or dissolution. The sample shells that passed the test were then subjected to a fracturing test and compared to the results of the fracturing test prior to exposure to the chemicals. The sample housing conforms to UL 1203 if the fracture force of the chemically tested sample housing indicates that the chemically tested sample housing can withstand at least 85% of the corresponding fracture force tested prior to exposure to the chemical.

By virtue of its material of manufacture, the housing 102 should also exhibit chemical compatibility with specific chemicals present in the 1 st or 2 nd site of a given NEC or the 1 st or 2 nd site of an IEC. Chemical compatibility refers to the stability of the housing when exposed to substances in hazardous location environments. The housing 102 is considered incompatible if it chemically reacts with substances in the environment. Therefore, in view of the number of different corrosive or caustic chemicals and substances used in various industrial facilities, compatibility testing is recommended to confirm chemical compatibility. Different facilities involving different caustic or corrosive materials may require housings of different materials to address the resulting problem. Strategic selection and formulation of housing materials may be required for some explosive environments if a generally optimal housing or material formulation cannot be practically determined or economically provided. In some cases, UL 1203 compliance of the housing may eliminate the need to perform chemical compatibility testing in the selected facility, and the chemical compatibility testing may therefore be considered optional.

The materials used to fabricate the housing 102 may likewise be strategically selected or otherwise formulated and formed to have specific configurations to achieve thermal management and surface temperature goals for the device 100 in operation. Some housing materials may exhibit better thermal performance for distributing and dissipating heat than other materials. For example, a particular polymer resin may be selected or customized and formulated or processed to achieve a housing 102 that will improve the thermal performance of the device 100 in use, both on the interior of the housing 102 and on its outer surface area, when protecting the power system, such that the outer surface area temperature is maintained at a level below that which can be ignited in a stage 1 or 2 site of a NEC or a stage 1 or 2 site of an IEC.

The shape and form factor (including size, profile, etc.) of the housing 102 can positively or negatively alter the overall thermal performance and surface temperature for any given housing material. For example, for a given device rating and operating voltage and current of a power system, a housing with a larger outer surface area will generally lower the surface temperature in use as compared to a housing with a smaller outer surface area. The housing structure may be designed to optimize and balance overall package size and configuration as well as thermal performance.

In some embodiments, the housing 102 may be made of a metal or metal alloy, a non-metallic insulating material (such as a high strength, high performance plastic), or a combination of metallic and non-metallic materials to alter thermal properties and other considerations discussed above, i.e., impact and chemical resistance. A wholly or partially encapsulated housing construction is likewise possible. In some cases, the interior of the housing 102 may likewise be filled, in whole or in part, with a dielectric material, dielectric fluid, potting material, or other fill medium (such as sand) to contain, absorb, or dissipate heat and energy of the energized electrical conductors and switching components in the device 102, thereby ensuring that the surface temperature of the housing 102 will remain below a selected target temperature, thereby providing the device 100 with a desired temperature rating or temperature rating.

The structural design of the housing 102 may also take into account heat distribution and dissipation, in addition to the materials used in its manufacture. The housing may be strategically configured to include more than one housing material throughout the housing 102 or at specific target locations in the housing. The housing sub-structures may be separately manufactured and provided for assembly to provide additional thermal insulation or conductivity in desired areas of the housing to selectively confine and distribute heat in selected locations in a strategic manner. Likewise, the wall thickness of the housing 102 may be varied to provide a greater or lesser degree of thermal conductivity and heat dissipation in selected portions of the structure or in certain areas of the housing structure at the most desirable locations. A conduit, channel, or pit may be formed to strategically capture the generated heat and more efficiently direct it to a desired location for dissipation. Heat sink materials or the like may be included to improve heat absorption and heat dissipation.

Active cooling elements are also possible, wherein a cooling fluid flows over or through the housing structure and the housing structure comprises suitable structures facilitating active cooling. The active cooling elements may be self-contained or provided separately, such as in a power panel application where multiple devices 100 may be provided, an active cooling system that counters the heat build-up in closely positioned devices 100 and mitigates the temperature effects that devices 100 may have on each other. The active cooling system may include cooling fans or pumps that circulate fluid in and around the plurality of devices 100 to effectively manage the surface temperature. The device 100 including the temperature sensor 158 (fig. 3) may provide a feedback signal to the active cooling system to turn on or off when needed. Thermoelectric devices can also be deployed as a feedbackable loop with a load device to reduce the available current through the device (thereby reducing heat).

The above thermal management considerations may be implemented in a variety of different combinations, some of which may offset or eliminate the need for other considerations. For example, in some applications, active cooling may eliminate the need for certain features of the housing, such as more complex shapes and form factors for dissipating heat over a relatively complex surface area.

The lateral sides 108, 110 of the housing 102 each include a connection recess 118, 120, 122 for connection to line-side and load-side circuitry, respectively. In the example shown in fig. 1, three connection recesses 118, 120, 122 are provided for connection to a three-phase power source on one of the sides 108, 110, respectively, and to a three-phase load-side device on the other side. The power source and the load may each operate with Alternating Current (AC) or Direct Current (DC). The device 100 as shown is configured as a circuit breaker and thus provides automatic circuit protection in response to a predetermined overcurrent condition that may be selected by a user within a certain range for input to the device 100 via the display screen 116, via another user interface including a remote interface, and/or preprogrammed into the device. The device 100 may operate according to a specified time-current curve or trip curve suitable for providing adequate protection to a connected load.

The display 116 may be a multi-function display to display different screens in response to user activation. In some embodiments, the display 116 may be touch sensitive, with the user making selections by touching selected areas of the display as prompted. Input selectors (such as buttons, knobs, etc.) may be provided separate from the display 116 for user interaction with respect to the display. An input selector, such as a toggle switch, may also be provided separate from the display 116 to serve as a manually operable on-off switch that may be intuitively manually operated by a user. In this case, the toggle switch may emulate a conventional toggle switch to change state to "on" or "off" in which there is no displacement of the mechanical switch contacts, as described below, the device 100 does not include a mechanical switch. Alternatively, an on/off feature may be built into the display 116 for operator use to implement a kill-switch function for the connected load-side device.

The display 116 may be a multi-function display to display different screens in response to user activation. In some embodiments, the display 116 may be touch sensitive, with the user making selections by touching selected areas of the display as prompted. Input selectors (such as buttons, knobs, etc.) may be provided separate from the display 116 for user input related to prompts or information presented on the display 116. However, it should be appreciated that in certain embodiments, the display or display array 116 may be considered optional and need not be included at all. In further embodiments, additional input/output elements may be provided, whether in the form of a display or other interface for user interaction with the device, both locally and remotely.

Fig. 2 is a simplified schematic diagram of the circuit protection device 100 in an exemplary solid state configuration. The device 100 includes input terminals 130a, 130b, 130c, each of which is connected via a connecting cable, conduit, or wire to one phase of a three-phase power source, represented in fig. 2 as line-side circuit 132. The apparatus 100 also includes output terminals 134a, 134b, 136c, each connected to a load-side circuit 136, such as motors, fans, lighting, and other electrical equipment in an industrial facility, where ignitable gases, vapors, or substances may be airborne as indicated at 138. The output terminals 134a, 134b, 136c may likewise be connected to an electrical load via a connecting cable, conduit or wire. Optionally, the device 100 may also include additional elements, such as auxiliary contacts and auxiliary connections, shunt trip features, under-voltage release features, communication ports and elements, power ports for communication and other purposes, and the like.

Solid state switching devices, shown as 140a, 140b and 140c, are disposed between respective pairs of input terminals 130a, 130b, 130c and output terminals 134a, 134b, 136 c. The exemplary arrangement includes series-connected pairs of Insulated Gate Bipolar Transistors (IGBTs) 142a, 142b, 142c, 142d, respectively, connected in reverse to each other, wherein each of the IGBTs 142a, 142b, 142c, and 142d includes a varistor element 144 connected in parallel to the IGBT. The reverse connected IGBTs in each pair exclude reverse current flow from the load side circuit 136 to the line side circuit 132 through the IGBTs in a known manner.

The IGBTs 142a, 142b, 142c, 142d are one form of semiconductor switches operable to allow current to flow between the respective input and output terminals (130a and 134a, 130b and 134b, and 130c and 134c) from the line-side circuit 132 to the load-side circuit 136, or to prevent current from flowing through the device 100, such that the load-side circuit 136 is electrically isolated from the line-side circuit 132. In short, a positive voltage applied from the emitter of the IGBT to the gate terminal causes electrons to be pulled across the body of the IGBT toward the gate terminal. If the gate-emitter voltage is equal to or above the threshold voltage, enough electrons are pulled toward the gate to form a conducting channel across the body region, allowing current to flow from the collector to the emitter. Substantially no current can flow through the body region if the gate-emitter voltage is below the threshold voltage, such that current between the input terminal and the output terminal can be enabled or disabled by controlling the gate-emitter voltage to connect or disconnect the output terminal of the apparatus 100 from the input terminal via the IGBT. Equivalent types of semiconductor switching elements other than IGBT elements may likewise be employed, including but not limited to Metal Oxide Semiconductor Field Effect Transistor (MOSFET) elements, bipolar transistor elements, silicon controlled rectifier elements (sometimes referred to as thyristors), and the like. The number of semiconductor switching elements may be changed to be greater or smaller than that shown in fig. 2.

Varistor elements 144 connected in parallel to each pair of IGBTs in the illustrated arrangement exhibit relatively high resistance when exposed to normal operating voltages and much lower resistance when exposed to larger voltages, such as associated with overvoltage conditions and/or electrical fault conditions. When varistor 144 operates in the low impedance mode, the impedance of the current path through varistor 144 is significantly lower than the impedance of the IGBT, and otherwise significantly higher than the impedance of the IGBT. This means that under normal conditions, the high impedance of varistor 144 causes all current to flow through the IGBT, but as an overvoltage condition occurs, varistor 144 switches from a high impedance mode to a low impedance mode and shunts or diverts the overvoltage induced current surge away from the IGBT to load side circuitry 136. As the over-voltage condition subsides, varistor 144 may return to the high impedance mode. Varistor 144 advantageously allows, for example, motor inrush current to flow through device 100, while additionally allowing the IGBTs to respond to an overcurrent condition after motor startup is complete. However, in other applications, the varistor may be considered optional and may be omitted.

As another thermal management feature, the solid state switching devices (e.g., IGBTs) 140a, 140b, and 140c in each arrangement may be encapsulated with strategically selected or otherwise formulated materials to improve thermal performance of the switching devices 140a, 140b, and 140c and/or to improve heat dissipation and distribution in use. The encapsulation material of the solid state switching devices 140a, 140b and 140c may be the same or different than the encapsulation material included in the housing construction, and in particular, its objective is to control or limit the operating temperature of the silicon in the solid state switching devices in normal circuit operation or in over current and electrical fault conditions to prevent overheating of the switching devices themselves or of the housing 102.

While an exemplary solid state switch arrangement is shown and described, other arrangements are possible to implement the solid state switch function in an arc-less manner. As described above, solid state switching devices avoid the type of arcing produced by mechanical switches, thus avoiding such arcing as a possible source of ignition in the 1 or 2 segment site of NEC or the 1 or 2 zone site of IEC.

Reliable termination of the line-side and load-side cables to the input and output terminals is important in view of the hazardous environment in which the device 100 is to be used, as loose connections can create heat and reliability issues, as well as possible ignition issues in hazardous locations. In the 2 nd place of NEC or the 1 st or 2 nd place of IEC, the input and output terminals are accessible from the outside of the housing 102. The locking terminal connection assembly and spring-biased terminal assembly may be used to receive and retain the ends of respective cables while reducing any tendency of the cable connections to loosen over time. However, such locking terminal assemblies and spring-biased terminal connectors may be considered optional in the 2-segment field of NEC or the 1 or 2-segment field of IEC, depending on the specific end use of the device 100 and its operating conditions.

In the 1-segment site of NEC, the input and output terminals may further be enclosed in additional housing portions to provide additional security. Such housing portions may be provided separately from housing 102 or may be integrally formed as extensions of housing 102 to isolate the input and output terminals from the explosive environment. In contemplated embodiments, a removable cover element may be provided to access the input and output terminals and complete the electrical connection with the input and output terminals within the housing of the housing portion. Line side and load side cable connections may be further established, for example, by providing access protection, sealing and grounding through the armored cable and cable gland to safely pass line side cables or load side cables through the outer shell of each housing section. When used with armored cables, a ground to ground path may be established via a cable gland. However, in all embodiments, armored electrical cables are not required and may not be used. Cable glands may also be used with non-armoured cables.

The housing 102 may be designed and manufactured in accordance with thermal management considerations to maintain surface temperatures below the applicable limits of a given installation in a stage 1 site of the NEC, and in some embodiments, the housing 102 may be fully or partially explosion proof in compliance with applicable standards for hazardous sites, although providing a relatively smaller and more economical housing as compared to conventional, larger and separately provided explosion proof enclosures, which will typically contain the entire circuit protection device. The housing 102 and any enclosure defined thereby may likewise comprise a vacuum chamber or may be filled with a dielectric fluid, dielectric material, or inert gas to reduce or prevent arcing at the terminal/cable interface or other locations of the housing.

To address the potential static charge build-up problem (which causes a potential ignition source to occur in the field 1 of NEC), the connection of the housing 102 to the electrical ground 146 is shown in fig. 2. In short, static electricity is the result of an electromagnetic imbalance between negative and positive charges in an object. The charging of the surface of the housing may be generated by surface charges related to another object, in particular an insulating part of the housing, or by charge induction to a conductive part of the housing. Surface charging can also occur during exposure to a high voltage DC power supply, which will cause ions to attach to the housing surface.

Regardless of how surface charging actually occurs, the connection to ground 142 allows any charge build-up on housing 102 to be safely dissipated without creating a source of ignition in the flammable/hazardous area. The housing 102 may be grounded to earth ground or chassis ground via a line wire or line conductor that is connected to an outer surface of the housing 102. In this way, any electrification on the exterior of the housing 102 will be quickly dissipated to ground as a current and avoid high voltage discharge events, which are typically manifested as sparks or shocks that may be generated by a person or tool used by a person, or which may otherwise occur in the presence of explosive air and cause ignition.

The housing 102 itself may also be made, in whole or in part, of an antistatic polymer or antistatic material that is weakly conductive from a charge accumulation perspective, but still considered insulative and non-conductive from a power system perspective protected by the device 100. In the first case, the antistatic material may improve the housing performance by reducing any tendency of the housing to become charged relative to the non-antistatic material, and this is another consideration in strategically selecting or otherwise formulating one or more materials to be used in the housing fabrication. If desired, an antistatic coating, encapsulation or shell can be provided on the outer surface of the housing, but chemical resistance and compatibility must still be ensured as described above. When the device 100 is directly connected to the housing/system ground plane in actual installation, a dedicated ground conductor for solving the electrostatic problem may not be necessary due to mechanical attachment and/or physical proximity to the ground plane.

Although a single ground connection is shown in fig. 2, more than one ground connection may be provided at any desired location in the structure of device 100. The ground conductor may be provided inside the device housing 102 in addition to or instead of the ground conductor connected to the outside of the device housing 102 as described above. When line-side and load-side connections to the terminals 130a, 130b, 130c of the apparatus 100 are established with armored cables that already include a ground path to ground, a ground connection for the housing 102 may also be established via a cable connector, such as a cable gland. Of course, in some cases, unshielded cables with or without cable glands may be used while still eliminating ignition sources in the device 100 and addressing static issues with an alternative ground connection.

In a field 2 of NEC or a field 1 or 2 of IEC, the device 100 will typically be protected by an enclosure and will therefore not be prone to electrostatic problems and discharge events. Thus, in an apparatus 100 for a 2 nd site of NEC or a 1 st site of IEC, a connection to ground 146 may or may not be necessary or desirable, and thus may be considered optional. However, with the apparatus 100, the enclosure containing one or more of the apparatus 100 need not be explosion proof, and conventionally provided explosion proof enclosures may be omitted.

Fig. 3 is a block diagram of the circuit protection device 100. The device 100 includes a processor-based microcontroller including a processor 150 and a storage device 152 having stored therein executable instructions, commands, and control algorithms as well as other data and information needed to properly operate the device 100. The memory 152 of the processor-based device may be, for example, Random Access Memory (RAM), as well as other forms of memory used in conjunction with RAM memory, including but not limited to FLASH memory (FLASH), programmable read-only memory (PROM), and electrically erasable programmable read-only memory (EEPROM).

As used herein, the term "processor-based" microcontroller shall refer not only to a controller device including the illustrated processor or microprocessor, but also to other equivalent elements, such as microcomputers, programmable logic controllers, reduced instruction setsCircuits (RISC), application specific integrated circuits and other programmable circuits, logic circuits, their equivalents, and any other circuit or processor capable of performing the functions described below. The processor-based devices listed above are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term "processor-based".

The device 100 also includes sensors 154, 156, 158 provided at numbers 1 through n, where n is equal to the number of switching poles in the device 100. Thus, for the three-pole device 100 shown in fig. 1 and 2, three sensors of each type may be included that detect current, voltage, and temperature, respectively, at corresponding locations in the device to assess actual operating circuit conditions in the device. In further embodiments, each switching pole may optionally be provided with additional temperature sensors for enhanced temperature monitoring at multiple locations in each pole. The sensors 154, 156, and/or 158 in turn provide input to the processor 150. Thus, by virtue of the sensors 154, 156, and/or 158, the processor 150 possesses real-time information about the current through each of the solid state devices 162 numbered 1 through n, where n is equal to the number of switching poles in the device 100.

The detected current is monitored and compared to a baseline current condition, such as a time-current curve programmed and stored in memory 152 or trip unit 160. By comparing the detected current to the baseline current condition, a decision can be made by the processor 150 to control the solid state switching element 162 by controlling the output voltage to the gate-emitter voltage in the IGBT as described above, stopping the conduction current to protect the load side from damaging currents. In some embodiments, trip unit 160 allows a user to select settings for the operation of trip unit 160 and to change the time-current response of device 100 within predetermined limits. As one such example, a user may select a current rating of the device 100 at a value from 50A to 100A, with the trip unit 160 applying an appropriate time-current curve for the selected current rating.

The detected voltage may also be monitored and used to make control decisions whether to operate the solid state switching element 162 to protect the load side circuitry and components from adverse operating conditions. Since the voltage and current are related, the detected voltage may be compared to the detected current to facilitate assessing the health of the device 100, identifying errors, and facilitating diagnosis and troubleshooting of the power system. As a further failsafe measure, voltage and current may be calculated from the sensed parameters and compared to sensor feedback to detect error conditions.

The detected temperature may also be monitored and used to make control decisions whether to operate the solid state switching elements 162 to protect the load side circuitry and components from adverse operating conditions. In addition, the sensed temperature may ensure that the conductors in the device 100 operate below the rated temperature of the particular hazardous location in which they are located. For example, if the nominal temperature is 200 ° f, the processor 150 may operate the solid state switch to disconnect and terminate the current when the operating temperature indicated by the temperature sensor rises to a temperature near 200 ° f that may ignite the airborne gases, vapors or species in the field 1 or 2 of NEC or the field 1 or 2 of IEC.

The processor 150 communicates with the input/output display 116 to provide feedback to the user and to accept input via the display 116.

In the example shown, the processor 150 receives line-side power through the power converter circuit 162. The power converter circuit 162 includes a voltage dropping component and an analog-to-digital conversion component when it is desired to provide Direct Current (DC) power to the processor 150 at a reduced voltage in a known manner. Converting line power to an appropriate level to power the electronic device avoids any need for a separate power source (such as a battery or the like) or separately provided power lines for the electronic circuitry and controls that would otherwise be necessary. But in some embodiments such a separate power source may indeed be included if needed or desired. The described controls may be implemented in electronic packages in various arrangements on one or more circuit boards, with the algorithmic control features programmed and stored in device memory.

Also included is a communication element 164 that can communicate data to remote locations, as well as other devices 100 as described further below, to assess the operation of the larger power system in local and remote locations relative to any particular device 100. Wireless and non-wireless transmission of data of interest is possible, including but not limited to current data, voltage data (including waveform data), temperature data, on-off state data of solid state switching elements, selected settings data, trip time data, etc., and such data may be stored and archived locally and remotely for analysis of the power system over time. Device 100 may also be remotely actuated via communication element 164.

While an exemplary architecture of the apparatus 100 has been described, it should be understood that certain elements shown in fig. 3 may be considered optional to provide more basic functionality. In addition, additional components may be added to make the operation of the device 100 more sophisticated and intelligent, as well as to provide additional functionality beyond circuit protection and circuit breaking functionality.

Since the solid state device 100 does not include mechanical switch contacts for connecting and disconnecting load side circuitry through the device 100, it is generally incompatible with conventional safety lockout or safety hang-tag features commonly used in mechanically actuated switching devices to ensure that a worker remains disconnected while performing maintenance or service tasks on the load side of the device 100. The safety lockout or safety hang-tag feature avoids the risk of a possible electrical cut for the worker by preventing reconnection of the load-side circuit through the device 100 unless a disabling procedure is followed.

As conventionally implemented, a mechanically actuated disconnect device is physically latched by a padlock or other mechanical locking device in the following manner: closing of the mechanically actuated circuit interrupting device is physically prevented until maintenance or servicing tasks are completed to ensure worker safety on the load side of the device. Typically, access to a mechanical unlocking device (such as a key or special tool required to unlock the device and allow the mechanical switch contacts in the recloser) is typically limited only to one or more specific personnel with regulatory authority and specific training to properly complete the security listing procedure to unlock the device to reclose the circuit.

Also, and as conventionally implemented, in some cases, multiple physical locks are used in combination to mechanically latch conventional mechanically actuated switching devices in an open position to prevent the mechanical switch contacts from being reclosed while performing maintenance procedures. Each of the provided physical locks may be unlocked or branded only by a different person with a unique key, such that a combination of persons is required to remove all locks before the device can be reclosed. Such conventional safety lockout/tagout procedures using physical locking devices can effectively ensure that the conventional mechanical actuation device is inadvertently or unintentionally closed when the maintenance task is completed.

By eliminating the mechanically actuated switch contacts of conventional devices, the device 100 thus requires a new lockout/tagout feature and associated safe mode of operation to provide a substantial degree of lockout/tagout safety assurance, ensuring worker safety and managing ignition risks in hazardous locations. The device 100 thus includes a latching component, which is represented in fig. 3 as latching component 166. As described below, the lockout feature 166 may correspond to one or more lockout features that may be monitored by the processor 150, electronically implemented via the processor 150 and device controls, or electronically assisted or confirmed by the processor 150 and controls of the device 100, respectively.

The latching component 166 and corresponding latching component, when described in the context of and in connection with the following apparatus 100, differs from conventional apparatus that are advantageously designed to achieve enhanced safety in hazardous location operations, and the benefits and advantages of the latching component described herein extend more generally to other types of switch breaking devices and end use applications that pose similar electrical cutting or ignition risks in the maintenance of electrical load and load side circuits that require safety latching or safety flagging features or make safety latching/flagging features and procedures desirable.

Accordingly, the device 100 including the latching component of the invention disclosed herein is provided primarily for purposes of illustration and not limitation. The latching components described herein may generally be used in any circuit protection or circuit interrupting device desired to meet applicable standards and regulations relating to worker safety in and around energized power systems. Such standards and regulations may include only OSHA safety requirements, for example for "hazardous energy control" (29CFR 1910.147), and NFPA standards 70E and 79, which provide guidance to verify that any stored energy has been properly eliminated or controlled to ensure that personnel will not be injured or exposed to electrical or mechanical energy while performing tasks. Remote actuation of the circuit protection devices, circuit breaking devices and switching devices creates an additional risk that personnel performing device maintenance can be electrically cut without the presence of a lockout device, so the lockout provisions must prevent all opportunities for energizing the circuit regardless of the type of input.

Fig. 4 is a front view of the circuit protection device 100 illustrating exemplary safety lockout features that may be used alone or in combination to achieve safety lockout features and functions. Fig. 5 is an end view of the circuit protection device 100 with the example safety lockout member engaged. Fig. 6 is an end view of the circuit protection device 100 in a connected state with the example safety lockout features disengaged. With the provision of latching components and features, the device 100 can be securely held or maintained in an open or tripped state via the latching components, wherein the load side circuitry is electrically isolated from the line side circuitry by the solid state switches in the device 100. When the device 100 is in a lockout state, mode or condition, the device 100 cannot be inadvertently reconnected to its connected state when a worker is performing a desired task for the electrical load and load-side circuit connected through the device 100 unless a prescribed listing procedure is followed. A safety guarantee is thus provided that the device 100 remains disconnected until the maintenance tasks on the load side of the device 100 are completed.

As shown in fig. 4-6, the front face 180 of the device 100 includes the display 116 and a mechanical toggle switch 182 adjacent the display 116. In contemplated embodiments, the display 116 or the toggle switch 182 may be used to effect on/off changes in the state of solid state switching elements in the device 100, but in some embodiments the device 100 may alternatively be provided with one or the other, but not both, of the display 116 and the toggle switch 182.

The mechanical toggle switch 182 is selectively positionable on the front face 182 of the device between positions designated "on" and "off. More specifically, the mechanical toggle switches 182 in the illustrated example can be rotated back and forth less than 180 ° from each other about the axis of rotation of the mechanical toggle switches 182 between the specified on and off positions (although embodiments are contemplated in which the toggle switches can be rotated about 90 ° or even less degrees). The "on" position in the contemplated example is shown in fig. 6 and in phantom in fig. 5, while fig. 4 and 5 show the toggle switch 182 in the "off position. The toggle switch 182 serves as an intuitive and easy-to-use mechanical input selector for the user to turn the device on or off as desired, while also providing the user with a visual indication of whether the device 100 is on or off based on the position of the mechanical toggle switch 182.

The mechanical toggle switch 182 mimics the on/off operation of known devices including toggle switch-like input selectors, but without any mechanical actuation of the switch contacts. Thus, the repositioning of the mechanical toggle switch 182 in the device 100 does not cause any mechanical actuation of the mechanical switch contacts, as no mechanical switch contacts are provided in the device 100. In addition, the repositioning of the mechanical toggle switch 182 does not directly operate the solid state switches in the device 100 to achieve the desired open (disconnect) or close (connect) function. The mechanical toggle switch 182 instead serves merely as a user input to the electronic controls of the device 100 to effect an electronic state change of the solid state switch inside the device 100 to effect the desired on/off or connect/disconnect function. Based on the position of the toggle switch 182, the position of the toggle switch may be sensed, otherwise detected, or transmitted to provide control inputs to the processor 150 (fig. 3). The processor 150 or device controller applies (or does not apply) sufficient gate-emitter voltage to the solid state switching element in response to the toggle switch position to conduct current (or not conduct current) and achieve a desired on or connected state, or alternatively to achieve a desired off or open state depending on the position of the toggle switch.

The mechanical toggle switch 182 may be securely latched at its distal end in the off position to an anchoring element 184 provided in the device 100 and project upwardly from the front face 180 adjacent the distal end of the toggle switch 182 when in the off position. Specifically, the distal end of the toggle switch 182 can include a first locking hole 185 (fig. 6) aligned with a second locking hole 186 (fig. 5 and 6) of the anchor element 184. When the latch apertures 185, 186 are aligned, a locking element, such as a shank 188 of a padlock 190 (shown in phantom in fig. 4 and 5), may be inserted through the aligned latch apertures 185, 186 to physically lock the mechanical toggle switch 182 in the open position. The latched mechanical toggle switch 182 is an effective safety lockout for the device 100 to ensure that the device 100 remains in an open state, thereby electrically isolating the load side of the device 100 from the line side circuitry.

In contemplated embodiments, the anchor element 184 may be provided as a metal plate or reinforced plastic element that is securely mounted to the device 100 and has sufficient structural strength to resist any attempt to remove the lock by force. More than one anchoring element 184 may be provided as desired to further improve the latching arrangement. Although the example anchor element 184 is shown and described, in additional and/or alternative embodiments, other anchor elements are possible, with the end result being to securely lock the on/off input selector in the off position to prevent the device 100 from being turned back on.

With the exemplary toggle switch 182 and anchor element 184, the device 100 may be safely latched as described above to ensure that the device 100 is safe for workers attending load-side maintenance procedures. The padlock 190 may be turned on only by authorized personnel having a key to unlock the toggle switch 182 so that personnel without a key cannot turn on the device 100 via the toggle switch 182 locked in the off position. While the toggle switch 182 and padlock 190 are described and shown to achieve a simple locking arrangement, on/off input selectors other than toggle switches and locking elements other than padlocks may also be used to implement mechanical lockouts for other non-mechanical properties of the solid state device 100 in switch breaking operations.

As mentioned, the mechanical toggle switch 182 may be used as a separate on/off switch input selector including safety lockout capability, or may be used in conjunction with the display 116. When the toggle switch 182 and the display 116 are provided separately, the display 116 may provide visual user feedback to the user as the toggle switch 182 moves between the on and off positions and provide another visual cue to the user as to whether the status of the device is on/connected or off/disconnected. Specifically, when the mechanical toggle switch 182 is moved to the on position, the processor 150 may operate the solid state switch to conduct current, confirm that current is being conducted through a sensor disposed in the device 100, and cause an on indicator to be presented on the display 116 to confirm to the user that the device 100 is actually on. Additionally, when the mechanical toggle switch 182 is moved to the open position, the processor 150 can operate the solid state switch to become non-conductive, confirm that the load side terminal is electrically isolated by a sensor disposed in the device 100, and cause an open indicator to be presented on the display 116 to confirm to the user that the device 100 is actually open.

When providing confirmation to the user of the actual on or off state of the device 100, additional safety is provided in the event of device control failure or solid state switch failure. In this case, the mechanical toggle switch 182 may move to the off position, but the solid state switch remains "on" to conduct current to the load side. In response to such conditions, which may be detected with a load side sensor on the device 100, the display 116 may provide a clear warning on the display 116 that the device 100 is not actually "off" as the user would expect by moving the toggle switch 182 to the on or off position. Alerts and notifications of error conditions may also be generated for the device 100, and if desired, the line side circuitry may be electrically isolated locally or remotely via operation of upstream switching devices in the power system to ensure safety of workers in completing desired load side tasks.

While a confirmation on/off status indication is described by the display 116, indicator lights and other confirmation/feedback features may also be used to provide confirmation to the user of the actual status of the solid state switch (e.g., on or off), or to effectively alert the user of a detected device error or malfunction (in addition to or in lieu of the display 116). In some embodiments, an audio alert feature may be provided as an enhanced confirmation or warning feature using a verbal message such as "device on", "device off", or "warning, device remain on", "warning, device remain off". Confirmation or warning data messages may also be automatically generated and transmitted to the remote device for system level assurance, analysis, and record keeping purposes, to record connections and disconnections made by the device, times of connections and disconnections, sensor and mechanical toggle switch states, or other data of interest.

In embodiments that do not necessarily include a mechanical toggle switch 182, the display 116 may be touch sensitive and may define an on/off button 192, a safety lockout button 194, and a lockout deactivation element 196. The on/off button 192 may be used for ordinary on/off changes in the state operation of the device 100, where the controls of the device 100 thus control the solid state switches without the need to toggle the switch 182 or other mechanical input selector. Audio and/or visual feedback may be provided to the user confirming that the device 100 is actually on or off, or that an appropriate error has been detected to warn.

When the display 116 is a touch sensitive display, as input selections are made by the user, graphical icons may be provided in the home screen display and subsequent displays, and user interface selections may be provided in menus or sub-menus. A home screen button may be provided adjacent the display 116 and an on/off switch may be provided on the main display for ease of access. A user may touch, swipe or otherwise utilize other forms of contact in the manner of other types of smart devices (e.g., smart phones or tablets) in an easy-to-use display driven interface to operate the display 116. Another screen display including a safety lockout button 194 may be presented when the user turns off the device 100 via an on/off input selector in the home screen. Likewise, when the safety lockout button 194 is activated, another screen display may be presented that includes a lockout deactivation element 196. Many variations in this regard are possible.

When a mechanical toggle switch 182 is provided in addition to the display 116, a separate or independent on/off button 192 in the display 116 may be considered optional and need not be included. When the mechanical toggle switch 182 is moved to its on or off position, the display 116 may automatically switch to a different screen display that includes on or off confirmation so that the user may view the device 100 in response to the user's selected position of the mechanical toggle switch 182. When lockout is activated, the toggle switch 182 may be disabled from a control perspective to further ensure that it cannot be used to turn the device back on until the electronic lockout condition is properly deactivated according to the following discussion.

In contemplated embodiments where the display 116 is not a touch sensitive display, additional input selectors may be provided in the form of buttons or any alternative form desired by the user to select or make on/off inputs, safety lockout inputs, and lockout deactivation inputs independent of or in combination with the display 116. In contemplated embodiments, additional input buttons may be multi-functional and may be coordinated with the screen display for intuitive device operation by the user in the main screen and associated screens for selecting different options, or the input buttons may be provided with tabs or the like, with each input button being used for only one purpose (e.g., on/off selection), in a menu-driven user interface.

When desired, the safety lockout button 194 (or corresponding input selector) may be manipulated by a user to activate the electronic lockout feature, wherein the on/off button 192 (or other corresponding input selector including, but not limited to, the toggle switch 182) is disabled such that any further user manipulation of the on/off button 192 (or other corresponding input selector) is not effective to change the state of the solid state switches in the device 100. Thus, when the device 100 is turned off and when latching is enabled, the device control will ignore any attempt by the user to re-turn the device 100 on via the on/off input selector. As previously described, actual changes in the state of the solid state switches in the device 100 (as detected by sensors in the device 100) may be visually confirmed to the benefit of the user, and safety warnings or error notifications may be made via the device 116 regarding possible error conditions or malfunctions of the device 100. The display 116 may also visually indicate to the user that the latch has been activated, and may also provide audio confirmation.

Once the lockout button 194 is activated on the display 116, the device 100 remains in the lockout state and may not be turned back on until the lockout deactivation element 196 is properly used to flag the lockout element and deactivate the lockout feature. In one example, when the user selects lockout deactivation element 196, the user is presented with a screen to enter a listing password. Of course, in contemplated embodiments, the hang-up code will only be known to one or more designated personnel authorized to reconnect and thus reclose the device for restoring operation of the power system on the load side of the device 100. Unless the correct hang-up code is presented, the lockout will not be deactivated and the on/off input selector will continue to be disabled and any use of it to attempt to turn on the device will be ignored.

Such exemplary lockout activation and tagout deactivation features, electronically implemented through display 116 and controls of device 100, may complement the toggle switch lockout described above or serve as a stand-alone feature. While the password deactivation feature has been described with respect to an electronic lock, other known features for authenticating the authority of a person or otherwise known and available include, but are not limited to, known biometric elements for identifying an authorized person's fingerprint or the like, to unlock the device interface and/or deactivate the security lockout.

When the mechanical toggle switch 182 and the display 116 are each present in the device 100, it is possible to enhance the lockout/tagout procedure and it has greater security than would be possible if only one of the conditions were provided. For example, one person may be required to unlock an electronic feature implemented through the display 116 with a desired code, and another person may be required to unlock the padlock 190 with a desired key to release the otherwise locked toggle switch 182 so that it may be moved to the on position to re-turn the device 100 on. If the mechanical lock is disabled to release the toggle switch 182, but the electronic lock remains activated (or vice versa), the controls in the device 100 will not allow the device to be turned back on. Such multi-step lockout/tagout procedures involving different personnel are desirable in hazardous locations to reduce any possibility of human error in operating the switches and thus increase worker safety and possible ignition issues if the device 100 is re-turned on before a maintenance service task is completed on the load side of the device 100.

As yet another locking feature to provide locking/tagout security, the front face 180 of the device 100 also includes a pair of respectively shaped locking openings 200, 202 sized to be spaced apart from one another to receive a physical mechanical locking element, such as a handle 204 (shown in phantom in fig. 4 and 5) of a padlock 206, through and between each locking opening 200, 202. Lock detection sensors 208, 210 (shown in phantom in fig. 5) are provided to detect insertion of a locking element (e.g., the handle 204), and when insertion of the handle 204 is detected, a control of the apparatus 100 may disable the on/off input selector to present a lockout state or condition. Thus, the mechanical action of the user inserting the handle 204 serves as an electronic control input via the lock detection sensors 208, 210, which in turn causes the device 100 to assume a secure lockout state.

In contemplated embodiments, the lock detection sensors 208, 210 may be optical sensors or limit switches in contemplated examples, but in additional and/or alternative embodiments, other types of sensors are possible. Optionally, the lock detection sensors 208, 210 may be controlled such that power is provided to the on/off switches only when they are in the "off" position, thereby avoiding unnecessary power consumption when the device 100 is turned on with the on/off switches in the "on" position. Thus, the lockout can only be activated via insertion of the lock after the device 100 has been shut off. This prevents potentially problematic latch activation when the device 100 is switched on, and prevents a resulting latch or a user from switching off the device 100 without first experiencing a prescribed latch deactivation, which may be done by only certain users for the reasons described above. While in some cases, latching of the device 100 in the on state may provide a desirable safety feature, protecting critical loads from being inadvertently switched off by an unauthorized person, such latching is an optional feature in some embodiments to ensure that the device remains on or connected, although in some cases not desirable. In particular, when operating in a hazardous location, it is important and should not be impeded to be able to quickly disconnect the device 100 and the load side when needed, without restriction and without time delay to deactivate the latch provided, so that the safety latch generally only remains in the open or disconnected state for the device 100 in the hazardous location. However, a prerequisite is that there is sufficient emergency override or lockout bypass features to allow the device 100 to be easily disconnected, even though it has been advantageously locked in the on or connected state, such lockout may be permitted in the on state.

Once lock detection is made by the sensors 208, 210, the device 100 remains off in the latched state with the on/off input selector disabled as long as the lock remains in place. The padlock 206 may be accessed only by authorized personnel having keys to remove the handle 204 so that personnel without keys cannot remove the handle 204. Removal of the handle 204 by the designated person is also detected by the sensors 208, 210, causing the device controls to deactivate the latch and allow the device 100 to be turned on again via the on/off input selector.

Automatic lock detection and associated lockout/tagout features may be used as stand-alone features or in combination with one or both of the mechanical toggle switch and electronic display driven lockout features described above. As described above, confirmation of a successful latch-up operation and user feedback, as well as notification of an error or malfunction, may be provided. When all three lockout features described are provided in combination, a redundant three-step lockout/tagout procedure is facilitated, which may involve three different personnel disabling each type of lockout provided. The automatic lock detection and security lockout/tagout features may also be provided with any of the other features described above, but not both, to facilitate a two-step security lockout/tagout procedure, which may involve two different persons disabling each lockout provided.

While exemplary mechanical and electrical safety lockout/tagout components and methods have been described and illustrated, further adaptations are possible. For example, a mechanical locking element other than a padlock may be used to lock a mechanical input selector, such as toggle switch 182, in an off position and/or inserted through a lock opening in device 100. Likewise, other types of lock detection sensors may detect other types of mechanical locking elements. Various forms of electronic latching may be provided using different user interfaces and safety features to ensure that the safety latching is successful for solid state devices 100 that do not include mechanically actuated switches, while ensuring that the safety latching can only be deactivated by authorized personnel, and also to ensure that the problem of additional ignition at hazardous locations is adequately addressed in the operation of the apparatus 100.

FIG. 7 is an exemplary algorithmic flow chart for a security lockout activation and deactivation routine 230 for the device 100. The algorithmic routine may be implemented, for example, by a processor-based control comprising the processor 150 and suitable sensors included in the device controls, or by an equivalent controller, depending on the various sensors provided to detect the state or position of mechanical or electronic input selectors (as they relate to voltage or current readings at different fields in the device), and other considerations discussed below.

At step 232, an on/off input element in the device 100, such as the toggle switch 182 (fig. 4-6) or other input selector, is monitored. At step 234, it is determined whether the on/off switch is in the off position as an input selection intended by the user to switch off the device 100 to effect disconnection of the load side circuit and the electrical load by the device 100. When a non-mechanical input selector is provided, at step 232, the activation of an input element may be monitored as the user selects the input element to change the state of the device from on to off or from off to on.

If at step 234 the on/off input element is not in the off position, the algorithm returns to step 232 and continues to monitor the on/off input element. Unless the on/off input selector is determined to be "off," it may be assumed that normal "on" operation of the device 100 to connect the line-side circuit and the load-side circuit through the device 100 is desired and no further action is required.

If it is determined at step 234 that the on/off input selection is "off," the device continues to operate the solid state switch to become non-conductive at step 236 so that current can no longer flow through the solid state switch to the load side terminal and the desired off is achieved. For the purposes of step 236, operation of the solid state switch refers to the operational controls and actions required to effect the provided state change of the solid state switch from a current conducting state to a non-current conducting state. For example, operation of the solid state switches refers to the voltage change necessary for the gate-emitter of the solid state switches to reach the non-conductive state of each solid state switch.

At step 238, the processor 150 may confirm whether the load side terminal of the device 100 is actually electrically isolated and powered down via the sensors provided in the device 100. For example, if true isolation is required, the load side terminal of the device 100 will have zero voltage and zero current detection from the applicable sensors. If non-zero voltage and current are found to be present, the load side terminals of the device 100 are not isolated as expected and, at step 266, the processor may generate a notification or alert to a local user interface (e.g., the display 116 described above) and any associated remote user interfaces. At step 268, feedback is provided to the user to visually show the user that device 100 remains on and off. The user's observation of the feedback provided will thus see that there is a problem with the device 100 that needs attention so that the load side circuit is actually shut off as intended.

If the processor 152 confirms at step 238 that the load side terminal of the device 100 is actually electrically isolated and powered down, a prompt may be presented on the local user interface (e.g., display 116) at step 240 whether a safety lockout is required. If not, the algorithm returns to step 232 and may continue to check to see if isolation is maintained. The algorithm thus confirms that disconnection may sometimes be required, but that a safety lockout is not required, since disconnection is not performed depending on the maintenance or service task to be performed on the load side. The prompt at step 240 also alerts the user that a safety lockout is available if desired, but needs to be activated by the user.

If a secure lockout is required at step 240, a lockout instruction may be presented to the user at step 242, such as inserting and installing a locking element as described above with respect to the exemplary padlock. Where multiple different types of latching components are provided, a step-by-step latching command may be provided. At step 244, installation of the lock as indicated may be detected, and in response to the detection, the on/off input element may be deactivated or disabled such that it does not respond to actually turning the apparatus 100 back on and effecting a change in state of the solid state switching element. At step 248, a confirmation may be provided to the user that the security lockout has been successfully activated. The worker can thus safely continue to perform tasks on the electrical load and the load-side circuit.

At step 250, the device waits for completion of the load-side program being executed, continues to confirm that electrical isolation is maintained, and provides confirmation of latch activation. At step 252, the user may be provided with instructions regarding deactivating the security lockout in order to turn the device back on, including removing any mechanical locks or deactivating electronic locks. A step-wise latch deactivation command may be provided for each type of latching component provided in the device 100.

At step 254, mechanical lock removal may be detected. At step 256, user authentication or authorization is received to disable any electronic locks, such as the passwords described above. If at step 258, it is determined that the received authentication is authorized, then at step 260, deactivation of the security lockout event is recorded. At step 262, the on/off input elements are reactivated. The user can now reclose the device with the on/off input element and in response the device controls will operate the solid state switches to become conductive and reconnect the load side circuit through the device 100.

If the received verification is not authorized at step 258, a notification or alert is generated to the remote device and person that a possibly incorrect attempt to reclose the device 100 has been made. Such a situation can be studied.

Depending on the type and number of latching features and features provided in the device 100, it is now believed that appropriate modifications to the algorithms and routines shown and described will be apparent. If some of the above-described latch types are not provided in the device 100, then some of the steps shown and described will not be performed. Likewise, additional steps may be taken to accommodate additional types of latches or additional latching features as desired. Although specific examples of processes are set forth above with respect to exemplary embodiments, similar effects and benefits may be achieved in other ways using other equivalent processes to accommodate additional or alternative mechanical locking features, various types of local and remote user interfaces, various different types of sensors for detecting mechanical locking elements, and various forms of user authorization and authentication.

Fig. 8 is a perspective view of a compliant explosion proof site circuit protection apparatus 300 in accordance with another exemplary embodiment of the present invention. The circuit protection device 300 includes the housing 102 described above, the housing 102 described having the chemical resistance, impact resistance, and thermal management features described above with respect to the device 100, but omitting the digital display 116 (fig. 1) of the device 100. As shown in fig. 8, a user may access a mechanical toggle switch 302 at an upper front portion of the housing 102 to manually activate the device 300 between "on" and "off states to connect and disconnect the load side of the device 300 from the line side. In other embodiments, manual actuators other than toggle switches may be employed. In some cases, the display 116 may be provided in addition to or instead of the toggle switch 302 or another manual actuator. Any of the above-described safety lockout features may be used in the device 100, alone or in combination.

Similar to device 100, device 300 may interconnect line-side or power circuits with electrical loads operating via Alternating Current (AC) or Direct Current (DC). The device 300 as shown is configured as a circuit breaker and thus provides automatic circuit protection in response to a predetermined overcurrent condition, which may be selected by a user within a particular range and input a local or remote user interface into the device, or otherwise preprogrammed into the device. The apparatus 300 may operate according to a specified time-current curve or time-current profile suitable for providing adequate protection for a connected load.

Fig. 9 is a simplified schematic diagram of the circuit protection device 130 in an exemplary hybrid configuration. The apparatus 300 includes input terminals 130a, 130b, 130c, each connected via a connecting cable or conduit to one phase of a three-phase power source, indicated as line-side circuit 132. The device 300 also includes output terminals 134a, 134b, 136c, each of which is connected to a load-side circuit 136, such as motors, fans, lighting devices, and other electrical devices in an industrial facility, wherein an ignitable gas, vapor, or substance may be airborne as indicated at 138 to create an explosive environment.

Between each pair of input terminals 130a, 130b, and 130c and output terminals 134a, 134b, and 136c are mechanical circuit breakers 304a, 304b, and 304c and solid state switching devices connected in parallel, the arrangement of which is shown as 140a, 140b, and 140 c. The exemplary solid state switch arrangements 140a, 140b and 140c comprise series-connected pairs of Insulated Gate Bipolar Transistors (IGBTs), wherein each pair comprises a varistor element connected in parallel to an IGBT, as described above. While an exemplary solid state switch arrangement is shown and described, other arrangements are possible to implement the solid state switch function in an arc-less manner. As described above, the solid-state switching device operates in an arc-free manner, and thus, in terms of arcing, the solid-state switching device itself does not create an ignition risk in a hazardous location.

The combination of the mechanical breakers 304a, 304b and 304c and the solid state switch arrangements 140a, 140b and 140c may improve the response time of the device 300 with respect to the device 100. However, the mechanical circuit breakers 304a, 304c operate with mechanical switch contacts and therefore are of particular interest for applications in hazardous locations because arcing can be a source of ignition. The solid state switch arrangements 140a, 140b, and 140c connected in parallel to the mechanical circuit breakers 304a, 304b, and 304c may limit the current in the mechanical circuit breakers 304a, 304, and 304c in the event of an overload or short circuit to reduce the intensity of any arc generated below the level required to create an ignition problem or otherwise completely preclude arcing.

The device 300 may likewise be connected to the electrical ground 146 to dissipate any electrification of the housing surface as described above, thereby eliminating possible ignition sources via electrostatic discharge as described above. In contemplated embodiments, the housing 102 of the device 300 may be made of a metallic or non-metallic material. In some cases involving certain metallic or non-metallic materials, the housing material, the filler material, and the encapsulation material must be strategically selected in order to address the static electricity problem. A combination of conductive and non-conductive materials may be utilized inside the device 300 and outside the device 300 to provide a path to electrical ground as appropriate.

The device 300 is also connected to the electrical ground 146 to dissipate any electrification of the housing surface as described above, thereby excluding possible ignition sources via electrostatic discharge. Line and load side connections may be established using a safety terminal assembly including, but not limited to, locking terminal features to prevent a connection that loosens over time after being initially secured with a fastener, and connections made to the enclosed terminal via armored cables and cable joints, thereby providing enhanced safety assurance for explosive environments.

Fig. 10 is a block diagram of a circuit protection device 300 that includes, in addition to the above-described elements in the device 100, a control input for a manual actuator 302 and a trip actuator 310 for operating a mechanical circuit breaker 312 that includes a mechanical switch.

With respect to the device 300, a mechanically actuated switch contact is included, so that the toggle switch input element 302, which causes the mechanical switch contact to open and close, can be mechanically locked in the open position to achieve a safe and secure lockout for the mechanical switch contact in the device. As described above, confirmation and feedback may be provided to the user that the mechanical switch contacts are actually closed to electrically isolate the load side terminals. The sensors in the device 300 can also confirm that the electronic solid state switch is non-conductive and that the load side terminal of the device is electrically isolated as needed. If the mechanical switch contacts but the electronic solid state switch remains conductive, an error condition can be detected and a warning and alert can be advantageously generated that an error condition exists or that a device failure has been detected. Multi-step safety lockout deactivation may be implemented as described above for redundant levels of safety, with multiple personnel participating in different aspects to enhance the safety lockout/tagout procedure and also to enable greater safety assurance of operation of the apparatus 300 in hazardous locations and optionally non-hazardous locations.

When a predetermined overcurrent condition occurs, the trip unit 160 causes the trip actuator 310 to displace the movable switch contacts and open the circuit through the device 300. The trip actuator may be an electromagnetic member, such as a solenoid, that can simultaneously displace the switch contacts of each mechanical breaker disposed in the apparatus 300, wherein the solid state switch arrangements 140a, 140b and 140c limit the current flow when the switch contacts are displaced. Thereafter, the manual actuator 302 may be used to reset the device 300 by closing the mechanical switch.

While an exemplary device architecture for the device 300 has been described, it should be understood that certain elements shown in fig. 10 may be considered optional for providing more basic functionality, and additional elements may be added to make the operation of the device 300 more sophisticated and intelligent.

Fig. 11 schematically illustrates thermal management features of the circuit protection devices shown in fig. 8-10. Although, as described above, the hybrid device 300 is capable of operating in an arc-free manner in many cases, additional considerations for addressing any occurring arcing must be considered since arcing may depend on the nature of the electrical fault and the voltage and current at which the power system is operated when the electrical fault occurs.

As shown in fig. 11, in addition to the thermal management features described above for the apparatus 100, the apparatus 300 includes additional features to ensure that any arcing that occurs in the operation of the mechanical circuit breaker is isolated from the surrounding environment or otherwise reduced to a level insufficient to cause ignition at an explosive site. Fig. 11 shows the housing 102 of the device 300 defining a first or primary housing 320 and a series of secondary housings 322a, 322b and 322 c. The secondary enclosure 322 serves to contain any arcing within the secondary enclosure while ensuring that airborne ignitable gases, vapors or substances cannot reach the secondary enclosures 322a, 322b and 322c and, therefore, cannot be ignited by operation of the mechanical circuit breaker.

In contemplated embodiments, the secondary housings 322a, 322b, and 322c may be hermetically sealed chambers that include respective switch contacts. The hermetically sealed chambers 322a, 322b, and 322c are fluid-tight such that any ignitable element that may penetrate the housing 102 into the hazardous location of the primary enclosure 102 cannot enter the sealed chambers 322a, 322b, and 322 c. The hermetically sealed chamber may also be a vacuum chamber or filled with an inert gas, so that the intensity and duration of the arc discharge will be reduced even if the arc discharge is not completely avoided when the switch contacts are opened and closed. Each of the secondary enclosures 322a, 322b, and 322c may be provided with additional insulation and materials to control and position any heat associated with arcing to the secondary enclosures 322a, 322b, and 322c within the larger enclosure 320. The housing within the housing construction of the housing 102 accommodates the other thermal management features described above while addressing the additional problems of mechanical switch contacts in explosive environments.

The secondary housings 322a, 322b, and 322c can be made of a different material than the rest of the housing 102, or a combination of materials that can be the same or different from the rest of the housing. For example, metal materials and plastics may be used to construct the chamber, while the remainder of the primary enclosure and housing may be entirely plastic. Many variations in this regard are possible. The secondary housings 322a, 322b, and 322c may be preformed to be assembled with the shell 102 at a separate manufacturing stage. The secondary housings 322a, 322b, and 322c may enclose some or all of the mechanical circuit breaker mechanisms without interfering with the path of movement of the switch contacts or their ability to move.

Each of the devices 100 or 300 may be safely used in a zone 1 or 2 of the IEC or a zone 1 or 2 hazardous location of the NEC without the need for a conventional, separately provided explosion proof enclosure, and the enhanced safety lockout/tagout features and intelligence as described above with respect to the device 100 are equally applicable to the device 300. The built-in anti-ignition features described above eliminate ignition sources or reduce them to levels insufficient to cause ignition. The apparatus 100 or 300 is therefore sometimes referred to as being ignition-proof, and thus eliminates any need for a separate explosion-proof housing. Thus, the apparatus 100 and 300 prevents a possible explosion that would be provided with a conventional explosion-proof housing to be safely controlled. Thus, the apparatus 100 and 300 can be safely operated at an explosive site and the cost and burden of a conventional explosion proof enclosure is eliminated while saving space in the power system.

Fig. 12 illustrates an exemplary electrical panel 400 including compliant hazardous location circuit protection devices including an array of devices 402, 404 arranged in two columns of devices. The devices 402, 404 in each column include the device 100 or 300 described above, and the devices 402, 404 may be represented by different ratings that provide different degrees of circuit protection for the various different loads serviced by the distribution board and its various branches. The electrical distribution board 400 typically includes its own enclosure, but due to the ignition-proof devices 402, 404 used on the electrical distribution board, the electrical distribution board's own enclosure may be a standard enclosure that is not designed to be explosion-proof. Because the devices 402, 404 are ignition resistant, they may be present in the panelboard enclosure without the need for a conventional explosion-proof enclosure in the panelboard enclosure. The panelboard housing protects the devices 402, 404 from environmental conditions, but the panelboard housing need not be explosion proof because the devices 402, 404 are ignition proof. Given that known electrical distribution boards can accommodate up to 84 devices, eliminating separate explosion proof enclosures and a common explosion proof enclosure provided separately significantly reduces the cost of operating the devices 402, 404 in hazardous locations. For large power systems comprising multiple distribution boards located at different locations, the cost is even further multiplied.

Safety lockout features such as those described above may be implemented at a system level in the electrical panel assembly. For example, a separate user interface may be provided with respect to the electrical distribution board, and mechanical and electrical latching of the types described above may be employed to act on or through the electrical distribution board user interface to disconnect all of the devices 402, 404 shown, and to latch all of the devices 402, 404 in the group via the electrical distribution board user interface when desired, thereby eliminating any need that may otherwise exist for separately disconnecting and latching each of the devices 402, 404. Likewise, group deactivation of the safety lockout features is possible, and the groups of devices 402, 404 may be collectively reconnected via the power panel user interface. Additionally, such a switchboard user interface may collectively display the on/off state or lockout state of each device 402, 404, individually or in groups. To the extent that the devices 400, 402 can advantageously be used individually to disconnect only selected ones of the connected electrical loads through each device 402, 404 in the panel, the panelboard user interface can likewise present a confirmation of the status and state of the devices 402, 404. For example, considering n circuits connected by a panel, circuits 1, 7, 12, and 19 in the panel may be locked via a selected device 402, 404 with a single lock (implemented by the panel rather than a separate device) while preventing the device from closing to energize circuits 1, 7, 12, and 19.

In such electrical panel installations comprising multiple devices 402, 404 operating simultaneously and in close proximity to each other, the thermal management issues of device operation in hazardous locations are further multiplied. Thermal effects can accumulate and adjacent devices can run hotter (i.e., have higher surface temperatures) than they can if used alone or at least spaced further apart from each other. The panelboard includes an enclosure, and while an explosion-proof enclosure is not necessarily required, the devices 402, 404 in the upper portion of the column may operate hotter than the devices 402, 404 in the lower portion of the enclosure as heat rises from the devices 402, 404 located in the lower portion. Then, in some cases, it may be desirable to actively cool the features and systems to avoid undesirable temperature effects on the operation of some of the devices 402, 404 or to account for elevated surface temperatures. As described above, the active cooling system may be disposed on or relative to the electrical distribution board to cool the devices 402, 404 at the system level rather than individually cooling the devices 402, 404. Variations and combinations of active cooling elements and systems are possible to achieve different cooling effects. The active cooling system may be triggered by ambient temperature sensing, temperature readings from either of the temperature sensors disposed in the devices 402, 404, or other factors and considerations that operate only on demand as actual demand dictates, or may alternatively operate continuously or intermittently as desired.

While the power board and power board enclosure are described above with respect to the devices 402, 404, similar benefits may be realized in other locations in the motor control center and power system, where the circuit protection devices 402, 404 are likewise conventionally located in non-explosion-proof enclosures. In view of the sensors and intelligence provided in the devices 402, 404 and the motor inrush features provided in the devices 402, 404, additional motor starting components may be integrated into the design of the devices 402, 404 and a combined circuit protector/motor starter provided in a single package, as opposed to the conventionally provided separately packaged and series connected circuit protector and motor starter assemblies, each of which requires an explosion proof enclosure for a hazardous location. Other dual purpose or dual function devices 402, 404 are also possible, which further reduce the cost of installing and servicing the power system by reducing the number of devices that need to be accessed, installed, and serviced in the power system.

Solid state or hybrid devices, such as those described above, may be constructed using a variety of different solid state switching elements, arrangements of solid state switching elements, and also implemented in a variety of different power electronics topologies. Various embodiments are contemplated involving varying degrees of on-state losses, propensity for arcing during operation, conduction losses, component count, relative complexity, ability to meet specific response time characteristics, simplicity or complexity of the operating algorithm, and the ability to integrate motor soft start or other features as needed. The solid state switching elements may be connected in series or in parallel using a modular arrangement to achieve a desired voltage rating scaling or a desired current rating scaling. To the extent that it is desirable to implement bypass contacts, the packaging material and thermal management features provided for the bypass contacts may be desirable.

Any of the solid state switching arrangements and hybrid switching arrangements shown and described above may include or be connected to line side electrical fuses to enhance circuit protection assurance by solid state switching elements addressing any defects or with respect to certain overcurrent conditions, or to improve response times to certain operating conditions.

The above-described device configuration and safety lockout/tagout features can be readily applied to implement a circuit protection device that is not a circuit breaker device, but is still ignition proof for use in either a 1 or 2-segment hazardous location of NEC and a 1 or 2-segment location of IEC without an explosion proof enclosure. For example, fusible switching disconnect devices that include a mechanical switch in combination with a fuse are discussed above. The use of the described chemical and impact resistant housing configuration, arcless switch operation, safety terminal assembly and thermal management features allows a solid state fusible switching disconnect device or hybrid fusible switching disconnect device to be easily configured with similar benefits, but providing varying degrees of circuit protection.

Also, the above-described chemically resistant and impact resistant housing configuration, arcless switching operation, safety lockout/tagout features, and certain thermal management features can be readily applied to implement switching devices that do not themselves provide overcurrent circuit protection, but are nevertheless ignition-proof for use in either a 1-or 2-segment hazardous location for NEC and a 1-or 2-segment location for IEC without separately provided explosion-proof enclosures. For example, mechanical relay switches and contactors are known that provide a circuit interrupting function but do not have the ability to operate independently and prevent overcurrent conditions. The use of the described chemical-resistant and impact-resistant housing configuration, arcless switching operation, safety lockout/tagout features, and thermal management features allows the solid state relay device or hybrid relay device and the solid state contactor device or hybrid contactor device to be easily configured for safe operation in explosive environments with intelligent lockout detection capability, lockout detection and verification.

The anti-ignition devices, such as those described, may be provided with any desired number of switching poles, including for example only unipolar, bipolar, tripolar and quadrapole devices, to suit the needs of any type of power system, including multiphase and multiphase power systems, while generally providing an anti-ignition function for use in either a 1 or 2 segment site of NEC or a 1 or 2 zone hazardous site of IEC.

Having functionally described the apparatus and applicable operating algorithms in light of the above description, those skilled in the art can therefore implement the algorithms via programming of a controller or other processor-based apparatus. Such programming or implementation of the algorithmic concept is considered to be within the purview of one skilled in the art and will not be described further.

It is now believed that the benefits and advantages of the inventive concepts have been fully shown in accordance with the disclosed exemplary embodiments.

Embodiments of a compliance switching device for hazardous locations have been disclosed. The compliance switch device includes an ignition-resistant housing, a line-side terminal, and a load-side terminal coupled to the housing, and a bus structure located in the housing and including at least one solid-state switching element operable in an arcless manner to connect the load-side terminal to the line-side terminal and disconnect the load-side terminal from the line-side terminal. The switching apparatus further includes an on/off input selector to change a state of the at least one solid state switching element, and a controller monitoring the state of the on/off input selector, and in response to a change in the state of the blocking input selector, the controller is configured to activate a safety blocking condition disabling the on/off input selector and prevent a change in the state of the at least one solid state switching element via the on/off input selector, whereby the switching apparatus is compliant for use in an explosive environment without the need for a separately provided explosion-proof housing.

Optionally, the controller may also be configured to confirm a change in state of the at least one solid state switching element and provide confirmation of the changed state to a user. The on/off input selector may be a mechanical input selector, and more specifically, may be a mechanical toggle switch that may be secured in an off position via a mechanical lock element, such as a padlock.

As a further option, an on/off input selector may be incorporated in the electronic display. The controller may be configured to deactivate the security lockout condition when a user provides a predetermined password.

Further optionally, the switching device may comprise a detector that senses the presence or absence of a mechanical lock element for the safety lockout. The detector may be configured to sense the presence or absence of the padlock handle.

Many different types of safety locking features may be provided in the switching device. The plurality of different types of safety lockout features may be operated in combination to achieve a multi-step lockout procedure. The plurality of different types of security lockout components may include a mechanical toggle switch and lock opening, a padlock and a detector that senses the presence of the padlock, and a multi-function display.

The switch may further include at least one mechanical switch contact in the bus structure, and the housing may include a sealed inner enclosure that houses the at least one mechanical switch contact, thereby preventing the switch contact from becoming an ignition source in an explosive environment. The at least one solid state switching element may be encapsulated. The switching device may function as a solid-state overcurrent protection device or may be configured as a hybrid overcurrent protection device. The housing of the switching device may be electrically grounded and/or exhibit antistatic properties. The housing is chemically resistant in hazardous locations.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.