阅读说明：本技术 用于拒绝向电气布线设备中的螺线管供电的电路和方法 (Circuit and method for rejecting power to a solenoid in an electrical wiring device ) 是由 约书亚·P·海恩斯 迈克尔·F·麦克马洪 于 2019-07-08 设计创作，主要内容包括：一种电气布线设备,其具有固态开关元件,该固态开关元件被定位在故障检测开关元件和螺线管线圈之间,以在断路器处于跳闸状态时防止螺线管线圈通电。固态开关元件可以具有栅极,当断路器处于复位状态时其接收接通固态开关元件的栅极信号以及当断路器处于跳闸状态时,其不接收栅极信号,使得第二开关元件断开。栅极可以被连接到线路端子并通过响应于断路器状态的机械开关或通过由处理器驱动的另一个固态开关接地,该处理器被编程为检测断路器是处于复位状态还是跳闸状态。(An electrical wiring device has a solid state switching element positioned between a fault detection switching element and a solenoid coil to prevent energization of the solenoid coil when a circuit breaker is in a tripped state. The solid state switching element may have a gate that receives a gate signal that turns on the solid state switching element when the circuit breaker is in a reset state and does not receive the gate signal when the circuit breaker is in a trip state, such that the second switching element is turned off. The gate may be connected to a line terminal and grounded through a mechanical switch responsive to the state of the circuit breaker or through another solid state switch driven by a processor programmed to detect whether the circuit breaker is in a reset state or a tripped state.)

1. An electrical wiring device comprising:

a fault protection circuit configured to provide a fault detection signal in response to detection of at least one type of predetermined fault condition;

a circuit breaker configured to couple a plurality of line terminals and a plurality of load terminals in a reset state and decouple the plurality of line terminals and the plurality of load terminals in a trip state;

a first solid state switch electrically coupled to receive the fault detection signal at a first gate, the first solid state switch turning on in response to receiving the fault detection signal at the first gate;

a solenoid electrically coupled to the first solid state switch such that the solenoid is energized when the first solid state switch is on, the solenoid generating a magnetic field when energized, the magnetic field moving the circuit breaker into the tripped state;

a second solid state switch connected in series with the first solid state switch and the solenoid, wherein the second solid state switch is open when the circuit breaker is in the tripped state such that the solenoid is prevented from energizing.

2. The electrical wiring device of claim 1, wherein the second solid state switch includes a second gate, wherein when the circuit breaker is in the reset state, the second solid state switch receives a gate signal such that the second solid state switch is on, wherein when the circuit breaker is in the tripped state, the second solid state switch does not receive the gate signal such that the second solid state switch is off.

3. The electrical wiring device of claim 2 further comprising a mechanical switch positioned to manage the gate signal input to the second gate of the second solid state switch.

4. The electrical wiring device of claim 2, further comprising a third solid state switch positioned to manage the gate signal input to a second gate of the second solid state switch.

5. The electrical wiring device of claim 4, wherein the third solid state switch has a third gate that receives a third gate signal from a processor programmed to determine when the circuit breaker is in the reset state and when the circuit breaker is in the tripped state.

6. The electrical wiring device of claim 1, wherein the first solid state switch is a silicon controlled rectifier.

7. The electrical wiring device of claim 1, wherein the second solid state switch is a silicon controlled rectifier.

8. The electrical wiring device of claim 1 wherein the second solid state switch is a bipolar junction transistor.

9. The electrical wiring device of claim 4, wherein the third solid state switch is a bipolar junction transistor.

10. The electrical wiring device of claim 4, wherein the third solid state switch is a field effect transistor.

11. A method of denying power to an electrical wiring device during an end-of-life condition, comprising the steps of:

providing a first solid state switch connected in series with a solenoid and a second solid state switch, wherein the second solid state switch is turned on in response to a fault detection signal to energize the solenoid to cause a circuit breaker to move from a reset state to a tripped state, wherein in the reset state a plurality of line terminals and a plurality of load terminals are coupled together, wherein in the tripped state the plurality of line terminals and the plurality of load terminals are decoupled;

turning on the first solid state switch to allow current to flow through the solenoid and the second solid state switch when the circuit breaker is in the reset state; and

when the circuit breaker is in the tripped state, the first solid state switch is opened so that power does not flow through the solenoid and the second solid state switch.

12. The method of claim 11, further comprising the steps of: using a mechanical switch coupled to the circuit breaker to selectively cause the first solid state switch to turn on in the reset state and to turn off in the tripped state.

13. The method of claim 11, further comprising the steps of: using a third solid state switch coupled to a gate of the first solid state switch to selectively cause the first solid state switch to turn on in the reset state and to turn off in the tripped state.

14. The electrical wiring device of claim 11, wherein the first solid state switch is a silicon controlled rectifier.

15. The electrical wiring device of claim 11, wherein said second solid state switch is a silicon controlled rectifier.

16. The electrical wiring device of claim 11, wherein the second solid state switch is a bipolar junction transistor.

17. The electrical wiring device of claim 13, wherein the third solid state switch is a bipolar junction transistor.

18. An electrical wiring device comprising:

a fault protection circuit configured to provide a fault detection signal in response to detection of at least one type of predetermined fault condition;

a circuit breaker configured to couple a plurality of line terminals and a plurality of load terminals in a reset state and decouple the plurality of line terminals and the plurality of load terminals in a trip state;

a first solid state switch electrically coupled to receive the fault detection signal at a first gate, the first solid state switch turning on in response to receiving the fault detection signal at the first gate;

a solenoid electrically coupled to the first solid state switch such that the solenoid is energized when the first solid state switch is on, the solenoid generating a magnetic field when energized, the magnetic field moving the circuit breaker into the tripped state;

a second solid state switch disposed in parallel with the solenoid, wherein the second solid state switch is closed when the circuit breaker is in the tripped state such that current is shunted from the solenoid.

19. The electrical wiring device of claim 18, wherein the second solid state switch includes a second gate, wherein when the circuit breaker is in the reset state, the second solid state switch receives a gate signal such that the second solid state switch is off, wherein when the circuit breaker is in the tripped state, the second solid state switch does not receive the gate signal such that the second solid state switch is on.

20. The electrical wiring device of claim 19 further comprising a mechanical switch positioned to manage the gate signal input to the second gate of the second solid state switch.

Technical Field

The present invention relates to wiring devices and, more particularly, to a method for denying power to a solenoid of a wiring device during a trip condition, including if an end-of-life condition has occurred.

Background

During an end-of-life condition, a Silicon Controlled Rectifier (SCR) responsible for triggering the interruption of power provided to the GFCI output terminals of a Ground Fault Circuit Interrupter (GFCI) may short. As a result, current will flow through the solenoid without obstruction until it fuses. Since industry standards governing GFCI require that devices that have reached end of life be able to reject power to the output terminals of the GFCI, the blowing of the solenoid can be problematic because it can no longer cause the power to the output terminals of the GFCI to be disconnected.

Conventional approaches to solving the problem of how to deny power supply under end-of-life conditions include: a mechanical switch is inserted in series with the inductor of the solenoid, which opens when the device trips. However, mechanical switches can cause undesirable arcing between the contacts when the switch is pulled (turned), and switches capable of withstanding such arcing are expensive. Accordingly, there is a need in the art for a method of denying power to a solenoid of a wiring device at an end-of-life condition that does not rely on a mechanical switch.

Disclosure of Invention

The present disclosure relates to an electrical wiring device that can deny power to a solenoid of the wiring device when the device is in a tripped state so that the solenoid will not blow if the SCR reaches the end of life. Instead, when the SCR reaches the end of life, the device will immediately trip whenever the device is reset, so that the device refuses to supply power to the GFCI output terminals in an end-of-life condition.

According to one aspect, an electrical wiring device comprises: a fault protection circuit configured to provide a fault detection signal in response to detection of at least one type of predetermined fault condition; a circuit breaker configured to couple the plurality of line terminals and the plurality of load terminals in a reset state and decouple the plurality of line terminals and the plurality of load terminals in a trip state; a first solid state switch electrically coupled to receive the fault detection signal at the first gate, the first solid state switch turning on in response to receiving the fault detection signal at the first gate; a solenoid electrically coupled to the first solid state switch such that the solenoid is energized when the first solid state switch is on, the solenoid, when energized, generating a magnetic field that moves the circuit breaker into a tripped state; a second solid state switch connected in series with the first solid state switch and the solenoid, wherein the second solid state switch opens when the circuit breaker is in a tripped state such that the solenoid is prevented from energizing.

In an example, the second solid state switch includes a second gate, wherein when the circuit breaker is in the reset state, the second solid state switch receives the gate signal such that the second solid state switch is on, wherein when the circuit breaker is in the trip state, the second solid state switch does not receive the gate signal such that the second solid state switch is off.

In an example, the electrical wiring device further includes a mechanical switch positioned to manage a gate signal input to the second gate of the second solid state switch.

In an example, the electrical wiring device further includes a third solid state switch positioned to manage a gate signal input to the second gate of the second solid state switch.

In an example, the third solid state switch has a third gate that receives a third gate signal from the processor, which is programmed to determine when the circuit breaker is in a reset state and when the circuit breaker is in a tripped state.

In an example, the first solid state switch is a silicon controlled rectifier.

In an example, the second solid state switch is a silicon controlled rectifier.

In an example, the second solid state switch is a bipolar junction transistor.

In an example, the third solid state switch is a bipolar junction transistor.

According to another aspect, a method of denying power to an electrical wiring device during an end-of-life condition includes the steps of: providing a first solid state switch connected in series with a solenoid and a second solid state switch, wherein the second solid state switch is turned on in response to a fault detection signal to energize the solenoid to cause the circuit breaker to move from a reset state to a tripped state, wherein in the reset state the plurality of line terminals and the plurality of load terminals are coupled together, wherein in the tripped state the plurality of line terminals and the plurality of load terminals are decoupled; turning on the first solid state switch to allow current to flow through the solenoid and the second solid state switch when the circuit breaker is in a reset state; and when the circuit breaker is in the tripped state, opening the first solid state switch so that power does not flow through the solenoid and the second solid state switch.

In an example, the method further comprises the steps of: a mechanical switch coupled to the circuit breaker is used to selectively cause the first solid state switch to be on in a reset state and to be off in a tripped state.

In an example, the method further comprises the steps of: a third solid state switch coupled to the gate of the first solid state switch is used to selectively cause the first solid state switch to turn on in a reset state and to turn off in a tripped state.

In an example, the first solid state switch is a silicon controlled rectifier.

In an example, the second solid state switch is a silicon controlled rectifier.

In an example, the second solid state switch is a bipolar junction transistor.

In an example, the third solid state switch is a bipolar junction transistor.

According to one aspect, an electrical wiring device comprises: a fault protection circuit configured to provide a fault detection signal in response to detection of at least one type of predetermined fault condition; a circuit breaker configured to couple the plurality of line terminals and the plurality of load terminals in a reset state and decouple the plurality of line terminals and the plurality of load terminals in a trip state; a first solid state switch electrically coupled to receive the fault detection signal at the first gate, the first solid state switch turning on in response to receiving the fault detection signal at the first gate; a solenoid electrically coupled to the first solid state switch such that the solenoid is energized when the first solid state switch is on, the solenoid, when energized, generating a magnetic field that moves the circuit breaker into a tripped state; a second solid state switch disposed in parallel with the solenoid, wherein the second solid state switch is closed when the circuit breaker is in the tripped state such that current is shunted from the solenoid.

In an example, the second solid state switch includes a second gate, wherein when the circuit breaker is in the reset state, the second solid state switch receives the gate signal such that the second solid state switch is off, wherein when the circuit breaker is in the trip state, the second solid state switch does not receive the gate signal such that the second solid state switch is on.

In an example, the electrical wiring device further includes a mechanical switch positioned to manage a gate signal input to the second gate of the second solid state switch.

Drawings

The invention will be more fully understood and appreciated from a reading of the following detailed description in conjunction with the drawings in which:

fig. 1 is a schematic diagram of a wiring device having a first example of a solid state switch for preventing blowing of a solenoid of a circuit breaker in the event of an SCR end-of-life event in accordance with the present invention;

FIG. 2 is a schematic diagram of a wiring device having a second example of a solid state switch for preventing blowing of a solenoid of a circuit breaker in the event of an SCR end-of-life event in accordance with the present invention;

FIG. 3 is a schematic diagram of a wiring device having a third example of a solid state switch for preventing blowing of a solenoid of a circuit breaker in the event of an SCR end-of-life event in accordance with the present invention;

FIG. 4 is a schematic diagram of a wiring device having a fourth example of a solid state switch for preventing blowing of a solenoid of a circuit breaker in the event of an SCR end-of-life event in accordance with the present invention;

FIG. 5 is a schematic diagram of a wiring device having a fifth example of a solid state switch for preventing blowing of a solenoid of a circuit breaker in the event of an SCR end-of-life event in accordance with the present invention; and is

Fig. 6 is a schematic diagram of a wiring device according to a sixth example of the present invention having a solid state switch for preventing blowing of the solenoid of the circuit breaker in the event of an SCR end-of-life event.

Fig. 7 is a partial schematic view of a wiring device according to the present invention having a seventh example of a solid state switch for preventing blowing of the solenoid of the circuit breaker in the event of an SCR end-of-life event.

Fig. 8 is a partial schematic view of a wiring device according to an eighth example of the present invention having a solid state switch for preventing blowing of the solenoid of the circuit breaker in the event of an SCR end-of-life event.

Fig. 9 is a partial schematic view of a wiring device according to the present invention having a ninth example of a solid state switch for preventing blowing of the solenoid of the circuit breaker in the event of an SCR end-of-life event.

Detailed Description

Referring to the drawings, wherein like reference numbers refer to like components throughout, there is seen in FIG. 1 an electrical wiring device 10 providing fault protection in accordance with the present invention. The electrical wiring device 10 includes a differential transformer L1 and a grounded neutral transmitter (neutral transmitter) L2. The differential transformer L1 includes a secondary winding coupled to a fault detector U1 (such as an application specific integrated circuit that can detect, among other things, ground faults) through a noise filtering circuit. Differential transformer L1 senses the current difference between the hot and neutral lines and provides a sensor signal to fault detector U1 via inputs (IN-, IN +). Fault detector U1 provides a fault detection signal on the SCR output line when the differential current (sensor signal) exceeds a predetermined threshold.

The fault detection signal from fault detector U1 is received at the gate of SCR Q1 which turns on and thus begins to conduct in response to the fault detection signal. When the SCR Q1 turns on and conducts in the middle of an AC line cycle, the solenoid K1A is energized for a short period of time (i.e., typically less than about 25 milliseconds), such that the armature of the solenoid K1A trips the circuit breaker 12 to move from the reset state to the tripped state. The circuit breaker 12 couples the plurality of LINE terminals (LINE HOT and LINE eu), the plurality of feedthrough load terminals (feeder HOT and feeder neutral), and the plurality of outlet load terminals (FACE HOT and FACE neutral) in the reset state, and decouples the plurality of LINE terminals (LINE HOT and LINE eu), the plurality of feedthrough load terminals (feeder HOT and feeder neutral), and the plurality of outlet load terminals (FACE HOT and FACE neutral) in the trip state.

If the fault condition is resolved, solenoid K1A is no longer energized and circuit breaker 12 may be manually returned to the reset position, for example, via a mechanical reset button. The electrical wiring device 10 may also include a controller U2 that provides additional functions including monitoring the status of the electrical wiring device 10. For example, the controller U2 may include support circuitry and be programmed to perform functions such as self-tests, miswiring detection, and status indications.

However, under potential end-of-life conditions, the SCR Q1 may short and allow power to flow through the solenoid K1A. Long-term current flow through solenoid K1A may cause solenoid K1A to blow. If solenoid K1A has blown, it can no longer trip circuit breaker 12 in the tripped condition to deny power to the GFCI output terminals. However, when the fault detector U1 detects a ground fault, the circuit breaker 12 can still be manually reset by the user even though the solenoid K1A is unable to trip the circuit breaker 12. As a result, although device 10 appears to be operational to the user, it is no longer able to provide ground fault protection and will not comply with regulations that specify that device 10 must be able to reject power to the GFCI output terminals (e.g., the feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and the FACE terminals (FACE terminals) FACE HOT and FACE NEU).

A first example of a solid state switch can be seen in fig. 1 that can prevent blowing of solenoid K1A so that even if SCR Q1 reaches its end of life, device 10 will refuse to supply power to the GFCI output terminals. In this example, the solid state switch includes an SCR Q3 connected in series between an SCR Q1 and a solenoid K1A. The gate of SCR Q3 is connected to LINE HOT via diode D2 and resistors R7 and R16, and is also connected to ground through resistor R35 and switch K1B. The switch K1B is connected to the circuit breaker 12 such that the switch K1B is closed when the circuit breaker 12 is in the tripped position and the switch K1B is open when the circuit breaker 12 is in the reset position. When the circuit breaker 12 is in the reset position and the switch K1B is open, the voltage at the gate of the SCR Q3 will be high and thus the SCR Q3 will be on. (in this disclosure, high and low voltages refer to voltages at which the associated solid state switches begin to conduct and stop conducting, respectively. similarly, when referring to solid state switches, on is used to refer to the conductive state of the solid state switch, and off refers to the non-conductive state.) in the event of a fault or if SCR Q1 has reached the end of life, SCR Q1 begins to conduct and thus energizes solenoid K1A, tripping circuit breaker 12. The trip of circuit breaker 12 closes switch K1B, effectively grounding the gate of SCRQ3, so that the gate voltage of SCR Q3 is low and SCR Q3 enters the open state, and K1A is electrically disconnected from SCR Q1.

After the circuit breaker 12 trips, resetting the circuit breaker 12 will open the switch K1B so that the SCR Q3 will turn on again and any future fault detection may cause the circuit breaker 12 to trip. Assuming that any fault condition will likely be resolved before the circuit breaker 12 is reset, the SCR Q1 will not conduct when the SCR Q3 turns on again, and thus the circuit breaker 12 will remain in the reset state until the SCR Q1 begins to conduct again. However, if the SCR Q1 begins to conduct because it reaches the end of its life, it will remain conductive after the circuit breaker 12 is reset. Thus, when the circuit breaker 12 is reset and the switch K1B is open and the SCR Q3 is on, current will be allowed to flow through the solenoid K1A immediately, causing the solenoid K1A to again trip the circuit breaker 12, since the SCR Q1 is in an end-of-life state. Thus, any attempt to reset the circuit breaker 12 will result in the circuit breaker 12 immediately tripping in the event that the SCR Q1 reaches the end of life. Thus, the device 10 will continue to deny power to the feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and the FACE terminals FACE HOT and FACE NEU under end-of-life conditions. However, it would not be possible to reset the device 10 and hold it in the reset state for any useful duration.

In fig. 1, the resistor R13 is included as a current sensor to allow the controller U2 to monitor the trip condition without interfering with the operation of the SCR Q1 or any other component.

Referring to fig. 2, the second example of a solid state switch again includes SCRQ3 positioned between SCR Q1 and solenoid K1A. The gate of SCR Q3 is connected to LINE HOT via resistor R7 and to ground through switch K1B, switch K1B being closed when circuit breaker 12 is open. When the circuit breaker 12 is in the reset position and the switch K1B is open, the voltage at the gate of the SCR Q3 keeps the SCR Q3 on. In the event of a fault or if the SCR Q1 has reached end of life, the SCR Q1 will become conductive and will trip the circuit breaker 12 because power is allowed to flow through the solenoid K1A when the SCR Q3 is also conductive. Tripping the circuit breaker 12 closes the switch K1B and effectively grounds the gate of the SCR Q3, thereby opening the SCR Q3 and disconnecting the solenoid K1A from the SCR Q1.

Referring to fig. 3, a third example of a solid state switch includes an additional SCRQ3 positioned between the SCR Q1 and the solenoid K1A. The gate of SCR Q3 is connected to LINEHOT via diode D2 and resistor R7 and to ground through resistor R35 and normally closed switch K1B. As a result, when the circuit breaker 12 is in the reset position and the switch K1B is open, the voltage at the gate of the SCR Q3 keeps the SCR Q3 in the on state and thus conducting, so that power will flow through the solenoid K1A when the SCR Q1 is on. In the event of a fault or if the SCR Q1 has reached end of life, the SCR Q1 begins to conduct and will trip the circuit breaker 12 by allowing current to flow through the solenoid K1A. Tripping of the circuit breaker 12 closes the switch K1B and effectively grounds the gate of the SCR Q3, thereby placing the SCR Q3 in a non-conductive state and electrically disconnecting the solenoid K1A from the SCR Q1.

In the example of fig. 2 and 3 (as in the example of fig. 1), after the circuit breaker 12 trips, resetting the circuit breaker 12 will open the switch K1B so that the SCR Q3 will turn on again and any future fault detection may cause the circuit breaker 12 to trip. Assuming that any fault condition will likely be resolved before the circuit breaker 12 is reset, the SCR Q1 will not conduct when the SCR Q3 turns on again, and thus the circuit breaker 12 will remain in the reset state until the SCR Q1 begins to conduct again. However, if SCRQ1 begins to conduct because it reaches the end of its life, it will remain conducting after circuit breaker 12 is reset. Thus, when the circuit breaker 12 is reset, and switch K1B is closed and SCR Q3 is on, current will be allowed to flow through solenoid K1A immediately, causing solenoid K1A to again trip the circuit breaker 12, since SCR Q1 is in an end-of-life state. Thus, any attempt to reset the circuit breaker 12 will result in the circuit breaker 12 immediately tripping in the event that the SCR Q1 reaches the end of life. Thus, the device 10 will continue to deny power to the feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and the FACE terminals FACE HOT and FACE NEU under end-of-life conditions. However, it would not be possible to reset the device 10 and hold it in the reset state for any useful duration.

In general, comparing fig. 2 and 3 with fig. 1, the inclusion of diode D2 and resistor R16 regulates the gate voltage to SCR Q3. More specifically, diode D2 ensures that the positive voltage is only provided to the SCR Q3 gate. The resistor R16 also limits the current through the SCR Q3 to prevent current exceeding the tolerance of the SCR Q3 from passing through the gate.

Referring to fig. 4, a fourth example of a solid state switch includes an SCR Q3 positioned between SCR Q1 and solenoid K1A. The gate of SCR Q3 is connected to LINE HOT through resistor R7 and to ground via a Bipolar Junction Transistor (BJT) Q7. The base of BJTQ7 is connected to output SHDN of controller U2. When the output SHDN is high, BJT Q7 turns on, grounding the gate of SCR Q3, causing SCR Q3 to turn off. Conversely, when the output of SHDN is low, BJT Q7 is no longer conductive. As a result, the gate of SCRQ3 goes high, causing SCR Q3 to turn on. Accordingly, BJT Q7, like switch K1B in the example described in connection with fig. 1-3, manages the gate voltage of SCR Q3.

In the reset state, the controller U2 does not send a signal through the output SHDN, so the BJT Q7 remains off, and thus the SCR Q3 remains on. As a result, in the event of a fault or the SCR Q1 has reached end of life, the SCR Q1 begins to conduct and the circuit breaker 12 can be tripped by allowing current to flow through the solenoid K1A and the SCR Q3. When the controller U2 detects a trip (e.g., by detecting a voltage at the input of U2PA2 that corresponds to the state of switch K1B tied to the circuit breaker 12 being high or low), U2 sends an output signal through output SHDN to turn BJT Q7 on, thereby disconnecting SCR Q3 and disconnecting SCR Q1 from solenoid K1A. When the device 10 is reset by the user, U2 will detect that the device is in a reset state (again through the PA2 input) and stop sending signals through the output SHDN, turning on the SCR Q3.

In the event that the SCR Q1 has reached end of life, power flowing through the SCR Q1 to the solenoid K1A will be disconnected by the SCRQ3, thereby preventing any blowing of the solenoid K1A. Resetting the circuit breaker 12 will open the switch K1B, indicating to the controller U2 that the device 10 has been reset. The controller U2 will stop providing a signal via output SHDN to close BJT Q7, which allows SCR Q3 to close so that power can flow through solenoid K1A. If the SCR Q1 is still operational, the device 10 will be ready to detect and respond to faults. If the SCR Q1 has shorted under an end-of-life condition, power will flow through solenoid K1A and cause the circuit breaker 12 to trip. Thus, the device 10 will continue to reject power to the feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and the FACE terminals FACE HOT and FACE NEU.

Referring to fig. 5, a fifth example of a solid state switch includes a BJT Q6 instead of an SCR, the BJT Q6 being positioned between the SCR Q1 and the solenoid K1A. The gate of BJT Q6 is connected to LINEHOT through resistor R7 and to ground via second BJT Q7. The gate of BJT Q7 is connected to output SHDN of controller U2. When the output SHDN is high, BJT Q7 turns on, grounding the base of BJT Q6, causing BJT Q6 to turn off and stop conducting. Conversely, when the output of SHDN is low, BJT Q7 is no longer conducting, and as a result, the base of BJT Q6 becomes high, causing BJT Q6 to turn on and begin conducting. Accordingly, BJT Q7 manages the base voltage of BJT Q6.

As a result, in the event of a fault or if the SCR Q1 has reached end of life, the SCR Q1 begins to conduct and trip the circuit breaker 12 by allowing current to flow through the solenoid K1A via the BJT Q6. When controller U2 detects a trip of circuit breaker 12 through the closing of switch K1B (which closes in response to the trip of circuit breaker 12 and opens when circuit breaker 12 is reset), controller U2 sends a high signal on output SHDN, closing BJT Q7 and causing BJT Q6 to open. In the event that the SCR Q1 has reached end of life, the power flowing through the SCR Q1 to the solenoid K1A will be disconnected by the Q7 closing, thereby preventing any blowing of the solenoid K1A. Resetting the circuit breaker 12 will open the switch K1B, indicating to the controller U2 that the device 10 has been reset. The controller U2 will stop providing a signal (or otherwise provide a low signal) via output SHDN to turn off Q7 which closes BJT Q6 so that power can flow from SCR Q3 to solenoid K1A. If the SCR Q1 is still operational, the device 10 will be ready to detect and respond to faults. If the SCR Q1 has shorted under an end-of-life condition, power will flow through solenoid KAI long enough to trip the circuit breaker 12, which will also prevent power from flowing through solenoid K1A and preventing any undesired blow out. Thus, while solenoid K1A remains operational, device 10 will continue to deny power to feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and FACE terminals FACE HOT and FACE NEU.

Referring to fig. 6, a sixth example of a solid state switch includes a BJT Q6 positioned between SCR Q1 and solenoid K1A. The gate of BJT Q6 is connected to LINE HOT through resistor R7 and to ground via resistor 13 and second BJT Q7. Like the example of fig. 5, the gate of BJT Q7 is connected to output SHDN of controller U2. When the output SHDN is high, BJT Q7 turns on, grounding the base of BJT Q6, causing BJT Q6 to turn off and stop turning on. Conversely, when the output of SHDN is low, BJT Q7 is no longer conducting, and as a result, the base of BJT Q6 goes high and turns on. Thus, BJT Q7 manages the base voltage of BJTJTQ 6.

As a result, in the event of a fault or if the SCR Q1 has reached end of life, the SCR Q1 begins to conduct and the circuit breaker 12 can be tripped by allowing current to flow through the solenoid K1A and the BJT Q6. When the controller U2 detects a trip of the circuit breaker 12 through the closing of the switch K1B (which closes in response to the trip of the circuit breaker 12 and opens when the circuit breaker 12 is reset), the controller U2 sends a high signal on the output SHDN, closing the Q7 and causing the Q6 to open. In the event that SCRQ1 has reached the end of life, the power flowing through SCR Q1 to solenoid K1A will be disconnected by Q6 breaking, thereby preventing any blow out of solenoid K1A. Resetting the circuit breaker 12 will open the switch K1B, indicating to the controller U2 that the device 10 has been reset. The controller U2 will stop providing a signal via the output SHDN to open the Q7 (or otherwise provide a low signal), which allows the Q6 to close so that power can flow from the SCR Q1 to the solenoid K1A. If the SCR Q1 is still operational, the device 10 will be ready to detect and respond to faults. If the SCR Q1 has shorted under an end-of-life condition, power will flow through solenoid K1A long enough to trip the circuit breaker 12, which will soon prevent power from flowing through solenoid K1A and preventing any undesirable blowing via Q6. Thus, while solenoid K1A remains operational, device 10 will continue to deny power to feedthrough terminals FEEDTHRU HOT and FEEDTHU NEU and FACE terminals FACE HOT and FACE NEU.

In general, an SCR (such as SCR Q3 in fig. 1-4) is superior to a transistor (such as BJT Q6 in fig. 5-6) in the position of a solid state switch connected in series with SCR Q1 and solenoid K1A because the SCR requires less current at the gate to turn on. Furthermore, once the SCR turns on, the holding current for holding on is less than the current required to hold the transistor on. In addition, SCRs can typically withstand higher currents. Transistors that can withstand the same current are relatively expensive compared to SCRs.

Further, as shown in the examples of fig. 1-3, the mechanical switch K1B is generally preferred over a transistor (such as BJTQ7) because it is easier to implement and continues to operate if the controller U2 fails.

In the above examples described in connection with fig. 1-6, a solid state switch, which is an SCR, BJT, MOSFET, or any other suitable switch, is turned on when the circuit breaker 12 is in the reset state and turned off when the circuit breaker 12 is in the tripped state. When the solid state switch is on, SCR Q1 is electrically connected to solenoid K1A; conversely, when the solid state switch is open, the SCR Q1 is electrically disconnected from the solenoid K1A, thereby preventing the solenoid K1A from blowing. The state of the solid state switch is determined by its gate/base voltage, which is managed by a mechanical switch or solid state switch in conjunction with controller U2. It should be understood that fig. 1-6 are provided as examples only, and that other configurations for managing the gate/base voltage of the solid state switches to electrically disconnect the solenoid K1A from the SCR Q1 are contemplated.

Although the solid state switch (e.g., SCR Q3 or BJT Q6) is shown in fig. 1-6 as being disposed in series between SCR Q1 and solenoid K1A, it should be understood that the solid state switch may be positioned anywhere in series with solenoid K1A such that current flow through solenoid K1A is interrupted and K1A is prevented from energizing. For example, returning to fig. 1, solid state switch Q3 may alternatively be positioned above solenoid K1A (i.e., connected in series between solenoid K1A and LINE HOT) or below SCRQ1 (i.e., connected in series between SCR Q1 and NEU), and still effectively break the current flowing through solenoid K1A when circuit breaker 12 is in the tripped state. In summary, a solid state switch may be placed in series with solenoid K1A to interrupt the current flow through solenoid K1A when circuit breaker 12 is in a tripped state (by opening).

In an alternative example, a solid state switch (e.g., SCR Q3 or BJTQ6) may be placed in parallel rather than series with solenoid Q1 to shunt current away from solenoid K1A when the circuit breaker 12 is in a tripped state, for example, as shown in fig. 7-9. Shunting current away from solenoid K1A will reduce the current flowing through solenoid K1A, preventing it from blowing. In this example, the operation of the solid state switches is reversed relative to the operation of the solid state switches described in connection with the series example (e.g., described in connection with fig. 1-6). In other words, when the circuit breaker 12 is in the reset state, the parallel solid state switch is open such that current will not flow through the solid state switch; however, when the circuit breaker is in a tripped state, the parallel solid state switch is turned on so that current will flow through the solid state switch, thereby shunting current from solenoid K1A. The parallel solid state switch remains open when in the reset state so that in the event of a fault, solenoid K1A may become energized and trip circuit breaker 12.

For example, fig. 7 shows a partial schematic view of a wiring device in which an SCR Q3 is placed in parallel with a solenoid K1A. (to the extent that the components are not shown in the partial schematic views of fig. 7-9, it should be understood that they may be implemented as appropriate as shown in the various examples of fig. 1-6.) the state of the SCR Q3 is managed by the mechanical switch K1B such that the SCR Q3 is open when the circuit breaker 12 is in the reset state and the SCR Q3 is open when the circuit breaker 12 is in the tripped state. When the SCR Q3 is turned on, the current through the SCR Q3 may be limited by the resistor R36. The current through the SCR Q3 as limited by the resistor R36 should be sufficient to shunt current away from the solenoid K1A in order to protect the solenoid K1A from blowing in an end-of-life condition. Thus, the example of fig. 7 operates in a manner similar to fig. 1 (except that SCR Q3 is connected in parallel with solenoid K1A, and mechanical switch K1B is closed when circuit breaker 12 is in a reset state, and open when circuit breaker 12 is in a tripped state).

As shown in fig. 8, the state of SCR Q3 may instead be managed by a solid-state switch (such as BJT Q7) in a manner similar to the example of fig. 4. However, as described above, because the SCR Q3 is connected in parallel with the solenoid K1A, its operation is reversed from that described in fig. 4. For example, when the circuit breaker 12 is in the reset state, the signals from the controllers U2, SHDN remain high, causing the gate of the SCR Q3 to be grounded (since the BJT Q7 is on) and remain off. Conversely, when the circuit breaker 12 is in the tripped state, SHDN remains low so that the base voltage of SCR Q3 is high and SCR Q3 remains on to shunt current from solenoid K1A.

As shown in fig. 9, the parallel solid state switch may be implemented by a transistor such as BJT Q6, as in the examples of fig. 5 and 6. However, the operation of the example of fig. 9 is the same as the operation of the example described in connection with fig. 8.

Although the fault detector U1 and the controller U2 are each shown in fig. 1-9 as a single microcontroller, it should be understood that in an alternative example, both the fault detector U1 and the controller U2 may be implemented as a single controller. Further, in other examples, one or both of fault detector U1 or controller U2 may be implemented as more than one microcontroller that acts in concert to perform the functions described for fault detector U1 and controller U2.

Further, while solid state switches have been shown in fig. 1-9 as SCRs and BJTs, it should be understood that MOSFETs or other suitable solid state switches may be used in alternative examples.

While various inventive embodiments have been described and illustrated herein, variations of various other devices and/or structures for performing the functions described herein and/or obtaining the results and/or one or more advantages described herein will be readily apparent to those of ordinary skill in the art, and each such variation and/or modification is considered to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. Accordingly, it is to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto; the inventive embodiments may be practiced other than as specifically described and claimed.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

All definitions, as defined and used herein, should be understood to predominate over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. The term "connected" should be interpreted as being partially or fully contained, attached, or joined together, even if certain intervening elements are present.

As used herein in the specification and claims, the phrase "at least one," when referring to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including each and at least one of each element specifically listed within the list of elements, and not excluding any combinations of elements in the list of elements. The definitions also allow that additional elements may optionally be present in addition to the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of a and B" (or, equivalently, "at least one of a or B," or, equivalently, "at least one of a and/or B") can refer, in one embodiment, to at least one a, optionally including more than one a, while B is absent (and optionally including elements other than B); in another embodiment may refer to at least one B, optionally including more than one B, with a being absent (and optionally including elements other than a); in yet another embodiment may refer to at least one a, optionally including more than one a, and at least one B, optionally including more than one B (and optionally including other elements); and so on.

It will also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are recited.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms (such as "about" and "substantially") is not to be limited to the precise value specified. In at least some cases, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed.

No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

In the claims, as well as in the specification above, all transitional phrases such as "comprising," including, "" carrying, "" having, "" containing, "" involving, "" holding, "" consisting of … … and the like are to be understood to be open-ended, i.e., to mean including but not limited to. The only transitional phrases "consisting of" and "consisting essentially of" shall be the closed or semi-closed transitional phrases, respectively, as described in section 2111.03 of the U.S. patent office patent inspection program manual.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. It is not intended to limit the invention to the particular form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the appended claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.