阅读说明：本技术 用于开关系统的监控装置 (Monitoring device for a switching system ) 是由 S·马林科维克 K·亨肯 A·比安科 Y·马里特 于 2017-06-08 设计创作，主要内容包括：用于开关系统(100)的监控装置(1、15),开关系统包括具有至少一个可动触头的触头组件(10)和用于致动所述可移动触头和断开/闭合触头组件(10)的运动链(11)。监控装置(1、15)包括：加速度计(2),适于定位在所述开关系统(100)的运动部件上并且能够确定所述运动部件的加速度数据(3)；控制单元,包括：第一处理单元(4),适于接收由所述加速度计(2)测量的加速度数据(3)并计算预定事件的定时瞬时(5)和与所述开关系统(100)相关的运动参数(6)；第二处理单元(7),适于接收预定事件的所述定时瞬时(5)和所述运动参数(6),并使用至少一个定时瞬时和至少一个运动参数来计算所述开关系统(100)的电气/机械参数(8)。还公开了一种用于监控开关系统(100)的方法。(Monitoring device (1, 15) for a switching system (100) comprising a contact assembly (10) having at least one movable contact and a kinematic chain (11) for actuating said movable contact and opening/closing the contact assembly (10). The monitoring device (1, 15) comprises: -an accelerometer (2) adapted to be positioned on a moving part of the switching system (100) and capable of determining acceleration data (3) of the moving part; a control unit comprising: -a first processing unit (4) adapted to receive acceleration data (3) measured by said accelerometer (2) and to calculate timing instants (5) of predetermined events and kinematic parameters (6) related to said switching system (100); -a second processing unit (7) adapted to receive said timed instants (5) and said kinematic parameters (6) of a predetermined event and to calculate electrical/mechanical parameters (8) of said switching system (100) using at least one timed instant and at least one kinematic parameter. A method for monitoring a switching system (100) is also disclosed.)

1. A monitoring device (1, 15) for a switching system (100), said switching system (100) comprising a contact assembly (10) having at least one movable contact and a kinematic chain (11) for actuating said movable contact and opening/closing said contact assembly (10), characterized in that it comprises:

-an accelerometer (2) adapted to be positioned on a moving part of the switching system (100) and capable of determining acceleration data (3) of the moving part;

-a control unit comprising:

-a first processing unit (4) adapted to receive acceleration data (3) measured by said accelerometer (2) and to calculate timing instants (5) of predetermined events and kinematic parameters (6) related to said switching system (100);

-a second processing unit (7) adapted to receive said timed instants (5) and said kinematic parameters (6) of a predetermined event and to calculate electrical/mechanical parameters (8) of said switching system (100) using at least one timed instant and at least one kinematic parameter.

2. Monitoring device (1, 15) according to claim 1, characterized in that the timing instant (5) of a predetermined event is calculated by detecting one or more of the following: an abrupt change in acceleration values, the presence or absence of a particular amount of frequency in the acceleration pattern, an increase above or decrease below a particular acceleration threshold, an abrupt change in acceleration direction, and/or a subsequent change in speed and/or direction of travel.

3. Monitoring device (1, 15) according to claim 1 or 2, characterized in that the predetermined event is selected among one or more of the following: opening of the contact assembly, closing of the contact assembly, beginning of movement of the moving part, completion of movement of the moving part, impact with a damper of the switching system, energization of an actuation coil of the switching system.

4. The monitoring device (1, 15) according to one or more of the preceding claims, characterized in that said motion parameters (6) are selected among one or more of the following: acceleration, velocity or position of a moving part of the switching system (100).

5. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the contact corrosion state and said at least one timing instant is the contact opening/closing instant and said at least one kinematic parameter is the absolute position of said movable contact at said opening/closing instant.

6. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the state of the spring travel of the actuation spring of said switching system (100), said state being determined by calculating the difference between the position at the instant of start/end timing and the position at the instant of opening/closing of said contacts.

7. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the speed of the movable contacts at predetermined timing instants.

8. Monitoring device (1, 15) according to claim 7, characterized in that the electrical/mechanical parameter (8) of the switching system (100) is the movable contact speed at closing/opening.

9. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the overtravel of said movable contact upon opening/closing, said overtravel being determined as the position/instant of the timing instant of the speed change sign.

10. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the state of a damping element of said switching system (100), said state being determined as the difference between the position, speed or timing of the timing instant of the impact on said damper and the position, speed or timing of the timing instant of the next overrun.

11. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that it comprises, for each phase, an accelerometer (2) suitable for being positioned on the moving part of the phases of said switching system (100) and capable of determining the acceleration data (3) of said moving part, said control unit comprising a third processing unit suitable for determining the differences or commonalities of the behaviour between said phases.

12. A monitoring device (1, 15) for a switching system (100), said switching system (100) comprising a contact assembly (10) having at least one movable contact and a kinematic chain (11) for actuating said movable contact and opening/closing said contact assembly (10), characterized in that it comprises:

-a plurality of accelerometers (2, 21, 22) adapted to be positioned at different locations of the kinematic chain (11) of the switching system (100), adapted to be positioned on a moving part of the switching system (100) and capable of determining acceleration data (3) of the moving part;

-a control unit comprising:

-a first processing unit (4) adapted to receive acceleration data (3) measured by said accelerometer (2, 21, 22) and to calculate timing instants (5) of predetermined events and/or kinematic parameters (6) related to said switching system (100);

-a second processing unit (7) adapted to receive said timed instants (5) and/or said kinetic parameters (6) of a predetermined event and to calculate electrical/mechanical parameters (8) of said switching system (100) using at least one timed instant and at least one kinetic parameter and/or at least two timed instants (5) and/or at least two kinetic parameters (6).

13. The monitoring device (15) according to claim 12, characterized in that it comprises a plurality of accelerometers (2, 21, 22) adapted to be positioned at different locations of the kinematic chain (11) of the switching system (100), the control unit comprising a fourth processing unit (9) adapted to determine a difference indicative of a change in behaviour of the kinematic chain (11).

14. A monitoring device (15) according to claim 12 or 13, characterized in that it comprises a plurality of accelerometers (2, 21, 22) adapted to be positioned on a single mechanical component of the kinematic chain (11) at the locations connected by a fixed connection.

15. Monitoring device (1, 15) according to one or more of the previous claims, characterized in that it comprises a further accelerometer, suitable for being connected to the frame of said switching system (100) and capable of determining acceleration data obtained from the global motion of said switching system (100), said control unit comprising a fifth processing unit suitable for correcting the acceleration data of said moving parts of said switching system (100) using said acceleration data obtained from the global motion.

16. A switching system (100) comprising a monitoring device (1, 15) according to one or more of the preceding claims.

17. Medium voltage switchgear comprising a monitoring device (1, 15) according to one or more of claims 1 to 15.

18. A method for monitoring a switching system (100), said switching system (100) comprising a contact assembly (10) having at least one movable contact and a kinematic chain (11) for actuating said movable contact and opening/closing said contact assembly (10), characterized in that it comprises:

-positioning an accelerometer (2) on a moving part of the switching system (100);

-determining acceleration data (3) of the moving part;

-calculating a timing instant (5) of a predetermined event using said acceleration data (3);

-calculating a motion parameter (6) related to the switching system (100) using the acceleration data (3);

-calculating an electrical/mechanical parameter (8) of the switching system (100) using at least one of the timing instants (5) and at least one of the kinetic parameters (6).

19. Method according to claim 18, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is a contact corrosion state and said at least one timing instant (5) is a contact opening/closing instant and said at least one kinematic parameter (6) is the absolute position of said movable contact at said opening/closing instant.

20. Method according to claim 18 or 19, characterized in that said electrical/mechanical parameter (8) of said switching system (100) is the movable contact speed at a predetermined timing instant and said at least one timing instant (5) is said contact closing/opening instant and said at least one motion parameter (6) is said movable contact speed at closing/opening.

Technical Field

The present invention relates to a device for monitoring electrical/mechanical parameters and other characteristics of a switching system. In particular, the present invention relates to a device for monitoring electrical/mechanical parameters of a medium voltage switchgear system by measuring the acceleration of one or more kinematic components of the kinematic chain that actuates the movable contacts of said switchgear. The invention further relates to a switching system (e.g. a medium voltage switchgear system) comprising a device for monitoring electrical/mechanical parameters, and to a method for monitoring electrical/mechanical parameters and other characteristics of a switching system.

Although in the following description reference will be made primarily to medium voltage switchgear systems, the apparatus of the invention has more general applicability for low, medium and high voltage applications.

Background

Known switching systems, such as medium voltage switchgear, are widely used in power networks and therefore must be reliable. Therefore, there is an increasing interest in providing them with additional monitoring functions to prevent possible malfunctions. Such faults can be both electrical and mechanical, and to prevent the latter, many methods of analyzing mechanical systems are proposed in the literature.

An important characteristic of a switching device, such as a circuit breaker, is on the one hand the contact distance and on the other hand the speed of the movable contact when the contact is closed or opened. It is known that the contact speed must be within a specified range in order for the circuit breaker to be able to interrupt the current. Therefore, each circuit breaker manufactured is generally subjected to a well-defined procedure of testing the mechanical properties of the circuit breaker by measuring the travel profile (i.e. the linear and/or rotational displacement of the moving parts as a function of time). These measurements are then analyzed to extract features defining relevant mechanical properties.

These measurements must be performed during the factory assembly process and the measurement system is typically removed after the circuit breaker is placed in the field.

However, in order to continuously assess the state and health of the circuit breaker, it is useful that similar measurements can also be performed during normal operation in the field. Furthermore, in the case of field measurements, it is desirable to extract more features that can describe the possible failure of the circuit breaker due to material fatigue or other problems over time.

The measurement of the movement of the movable contacts of circuit breakers has mostly been studied using stroke sensors, rotary encoders and, in some cases, also high-speed cameras or optical systems.

It is also known to use accelerometers as sensors for circuit breaker monitoring. Accelerometers are used, particularly attached to fixed, non-moving parts, in order to measure vibrations with more or less success. These measurements are a combination of many mechanical and environmental effects, and using these signals alone is often very difficult to determine the mechanical health of the circuit breaker components.

The signal obtained from the accelerometer is therefore used primarily to detect the time when an impact occurs between the two contacts. Another application is the detection of "noise" when friction in some components or vibration of the entire circuit breaker begins to become large.

Therefore, accelerometer-based monitoring methods are typically limited to measuring the moment when a shock occurs or some vibration occurs, which is affected by ambient temperature or vibration of other equipment at or near the circuit breaker installation site. They also measure indirect effects that have no direct relation to the primary motion.

Disclosure of Invention

It is therefore an object of the present disclosure to provide a monitoring device for a switching system, in particular a medium voltage switchgear, which allows to overcome at least some of the above-mentioned drawbacks.

In particular, it is an object of the present invention to provide a monitoring device for a switching system which can be used both for factory testing during manufacture and for field monitoring both after installation and under operating conditions.

Furthermore, it is an object of the present invention to provide a monitoring device for a switching system, which can be used to detect a plurality of electrical/mechanical parameters indicative of the status of various components of the switching system, thereby reducing the risk of failure.

In addition, it is an object of the present invention to provide a monitoring device for a switching system, in which the number of sensors used is reduced, thereby reducing manufacturing and maintenance costs.

Accordingly, in a first aspect, the present invention relates to a monitoring device for a switching system, in particular a medium voltage switchgear, comprising a contact assembly having at least one movable contact and a kinematic chain for actuating the movable contact and opening/closing the contact assembly. The monitoring device according to the invention is characterized in that the monitoring device comprises:

-an accelerometer adapted to be positioned on a moving part of the switching system and capable of determining acceleration data of the moving part;

-a control unit comprising:

-a first processing unit adapted to receive acceleration data measured by said accelerometer and to calculate timing instants of predetermined events and kinematic parameters related to said switching system;

-a second processing unit adapted to receive said timed instants and said kinematic parameters of a predetermined event and to calculate electrical/mechanical parameters of said switching system using at least one timed instant and at least one kinematic parameter.

This problem is avoided because an accelerometer is selected as the sensor and positioned on the moving part of the switching system.

In fact, the use of accelerometers directly on the moving parts of the switching system allows direct and accurate mechanical measurement of said moving parts and of the entire kinematic chain, with a considerable reduction in costs and sensor installation complexity compared to the existing travel curve and speed measuring devices.

Furthermore, the monitoring device according to the invention is different from previous devices based on accelerometers attached to fixed parts, which attempt to derive these values indirectly and are affected by the environment. In contrast, the device of the present invention provides a direct measurement of the acceleration data of the moving part of the switching system.

Using these data, it is possible to calculate the movement parameters of the movable part (acceleration, velocity, displacement) as well as the timing instants of predetermined events (for example, time-localized events such as opening/closing of contacts, start/end of movement of the movable part, impact with the damper of the switching system).

Then, a plurality of physical parameters of the mechanical system, and therefore the state of some component of the switchgear, such as the contacts, dampers or actuators, can be calculated based on at least one of said kinematic parameters and at least one of said timed instants of a predetermined event.

In practice, in the device according to the invention, the use of an accelerometer on the moving part allows the use of the same sensor for determining different properties. For example, accelerometer data may be used to identify the impact, i.e., the specific point at which the contacts are in contact, derived speed data may be used to determine the critical speed required for successful circuit breaker operation, and finally the displacement may be used to determine changes due to wear of the contacts or mechanical components.

In addition, the integration operation from acceleration to velocity and displacement is more robust than the inverse method, for example, starting from a travel sensor. In other words, one advantage compared to, for example, a travel sensor is the robustness of the method with respect to integration. In principle, velocity and acceleration can also be calculated by taking the derivative of the stroke, but these operations are mathematically unstable and can produce noise and therefore produce useless results.

For example, the instant of contact closure can be easily detected with an accelerometer, but not with a travel sensor. With the device of the invention, it is then also possible to determine the distance and speed at that instant in time. It is also possible to use separate sensors to determine all three properties, but in the device of the invention they can be obtained using only an accelerometer. Furthermore, since they are derived from the same sensor, they are also (in time) synchronized with each other.

Preferably, said timing instant of a predetermined event is calculated by detecting one or more of: an abrupt change in acceleration values, the presence or absence of a certain frequency quantity in the acceleration pattern, an increase above or a decrease below a certain acceleration threshold, an abrupt change in acceleration direction.

Examples of time-localized events for which timing instants can be calculated are: opening of the contact assembly, closing of the contact assembly, beginning of movement of the moving part, completion of movement of the moving part, impact with a damper of the switching system, energization of an actuation coil of the switching system.

In an embodiment of the monitoring device according to the invention, the determined electrical/mechanical parameter of the switching system is the contact corrosion status; in such a case, the calculated timing instant is at a contact opening/closing instant and the calculated movement parameter is the absolute position of the movable contact at the opening/closing instant. This position directly determines the physical length of the contacts or the length of the contact gap between the contacts.

In another embodiment, the monitoring device of the present invention can be used to determine the spring travel state of the actuating spring of the switching system by calculating the difference between the position at the start/end timing instant and the position at the contact opening/closing instant.

In a further embodiment of the monitoring device according to the invention, the determined electrical/mechanical parameter of the switching system is the speed of the movable contact at a predetermined timing instant, in particular at the time of closing/opening.

Another example of an electrical/mechanical parameter of a switching system that can be determined with the device of the invention is the overtravel of the movable contact at opening/closing, said overtravel being determined as the position/instant of the timing instant at which the speed changes sign.

In another embodiment of the monitoring device according to the invention, the determined electrical/mechanical parameter of the switching system is a state of a damping element of the switching system, which state is determined as a difference between a position, a speed or a timing of a timing instant of the impact damper and a position, a speed or a timing of a timing instant of the next overtravel.

It is noted that the aforementioned embodiments may also be combined, since (as mentioned earlier) in the monitoring device according to the invention the use of an accelerometer on the moving part allows the use of the same sensor for determining different properties. In a particular embodiment, the monitoring device of the invention comprises, for each phase of the switching system associated therewith, an accelerometer adapted to be positioned on the moving part of the phase of said switching system and capable of determining acceleration data of said moving part. In this case, the control unit suitably comprises a third processing unit adapted to determine differences or commonalities in behaviour between the phases.

In other words, by comparing acceleration data associated with similar points on the various phases, it can be determined whether the operation of the phases is synchronous or asynchronous, or whether there is co-behavior between the phases (e.g., due to overall movement of the switching system).

In practice, in a three-phase switching system, it is possible to position three accelerometers on each phase/pole in a symmetrical manner to measure each of three symmetrical kinematic chains connected to three independent moving contacts, which are excited by the same source. With this embodiment, it is possible to detect an asymmetry of the mechanical system, which may be caused by an asymmetric wear of a phase or an asymmetry of the system itself (e.g. due to a change in the geometrical distance of the system). For example, by combining the situation where the contacts of the three poles are closed, the problem of delayed switching off from one of the phases can be avoided.

In another particular embodiment of the invention, a monitoring device for a switching system comprises: a contact assembly having at least one movable contact; and a kinematic chain for actuating the movable contact and opening/closing the contact assembly. The monitoring device is characterized in that. The monitoring device includes:

-a plurality of accelerometers adapted to be positioned at different locations of the kinematic chain of the switching system, the accelerometers adapted to be positioned on a moving part of the switching system and capable of determining acceleration data of the moving part;

-a control unit comprising:

-a first processing unit adapted to receive acceleration data measured by said accelerometer and to calculate timed instants of predetermined events and/or kinetic parameters related to said switching system;

-a second processing unit adapted to receive said timed instants and/or said kinetic parameters of a predetermined event and to calculate electrical/mechanical parameters of said switching system using at least one timed instant and at least one kinetic parameter and/or at least two timed instants and/or at least two kinetic parameters.

In a particular embodiment, the control unit suitably comprises a fourth processing unit adapted to determine a difference representing a change in the behaviour of the kinematic chain, e.g. a difference of an instance between values detecting a difference between values detected by an accelerometer at various positions of the kinematic chain and a theoretical value of an ideally linked mechanical chain, which may indicate slack, loose connections or fatigue on the kinematic chain.

For example, in a possible embodiment of the invention, two or more accelerometers may be positioned on a single kinematic chain, with the emphasis on measuring separate components that are linked together in such a way that they should move together in a predetermined context depending on the mechanical design. This embodiment will allow to detect possible defects/slacks of the connection between the moving parts by analyzing the differences between the mechanical data (acceleration, speed, travel) between the different points in the system. In a preferred embodiment, the time delay between "shock" signals is used, which is a direct indication of slack. In the other, the signal is integrated twice, for example, to obtain a course curve. By making a geometric transformation, the two travel curves can be compared and from this the "delay" can be determined, the difference in their position.

In another possible embodiment using multiple accelerometers, two or more accelerometers may be positioned on a single mechanical component on the kinematic chain at locations connected by fixed connections so that they should move simultaneously in synchronism once the driving force is applied. The purpose of this embodiment is to detect elastic defects of the mechanical parts, such as material fatigue, and to measure the stresses undergone during the operation of the circuit breaker due to torsion, bending or specific vibrations of the parts, to name a few. The preferred embodiment would use two signals and convert them to the same reference frame. The common and relative movements can then be separated by taking the difference of the two signals. Changes in material properties, such as young's modulus or attenuation, may be detected by, for example, observing the frequency or damping of the relative motion.

The latter embodiment can be combined with the previous embodiment (positioning of the accelerometer on different parts of the kinematic chain) to measure and analyze how possible changes in the mechanical properties of one part in the mechanical chain affect the mechanical properties of other parts in the chain. The purpose of this embodiment is to isolate a single fault of the mechanical chain that changes function but does not cause a hard failure of the system before they cause a failure of the entire system.

In another particular embodiment of the invention, the monitoring device is provided with another accelerometer adapted to be connected to a reference point of the circuit breaker system, which in ideal cases should be fixed, but in practice is not fixed due to the non-rigidity of the circuit breaker mounting. The purpose of this embodiment is to correct the absolute motion of the circuit breaker once a certain point on the moving part within the system is analyzed. Furthermore, (excessive) movements of the circuit breaker can be detected, which should not occur, but may cause early problems and are therefore not allowed.

For example, the monitoring device may be provided with another accelerometer connected to the frame of the switching system and capable of determining acceleration data derived from the overall movement of the switching system. The collected data about the global motion is then used to correct/compensate the acceleration data of the moving part in order to obtain a more accurate determination of the actual motion of the moving part. In such a case, the control unit suitably comprises a fifth processing unit adapted to correct acceleration data of said moving part using said acceleration data derived from the global motion.

For the purpose of the present invention, the various processing units (i.e. the first to fifth processing units) that may be present in the monitoring device may be part of the same or different physical objects.

In another aspect, the invention also relates to a method for monitoring a switching system, the switching system comprising: a contact assembly having at least one movable contact; and a kinematic chain for actuating the movable contact and opening/closing the contact assembly. The monitoring method of the present invention is characterized in that the monitoring method comprises the steps of:

-providing an accelerometer on a moving part of the switching system;

-determining acceleration data of the moving part;

-calculating a timing instant of a predetermined event using said acceleration data;

-calculating a motion parameter related to the switching system using the acceleration data;

-calculating electrical/mechanical parameters of the switching system using at least one of the timing instants and at least one of the kinetic parameters.

Thus, the method of the present disclosure is based on the direct measurement of the acceleration at a defined point of the moving part in the amount of movement of the switching system and the subsequent integration of the acceleration signal to calculate the speed and movement/travel of that point and hence of the mechanical part to which it is attached.

The acceleration data is also used to calculate the timing instants of predetermined events, which are then used together with acceleration/velocity/displacement (AVD) signals (i.e. motion parameters) to calculate mechanical parameters of the system, such as: contact erosion, contact spring force, over travel, asymmetry, relaxation, bending, etc.

For example, the method of the present invention may be used to detect contact erosion phenomena. In this case, the acceleration data are used to determine the opening/closing instant of the contacts and the absolute position of the movable contact at said opening/closing instant. The travel can then be tracked over time so that any change thereof can be determined very accurately.

As another example, the movable contact speed at a predetermined timing instant (e.g., at the time of opening/closing) can be determined with high accuracy by determining the contact closing/opening instant and the movable contact speed at the time of closing/opening (from the acquired acceleration data).

In practice, the device of the invention allows to continuously and directly measure a large number of electrical/mechanical parameters of the switching unit by using low-cost accelerometer technology.

A switching system comprising a monitoring device according to one or more of the preceding claims is also part of the invention.

Drawings

Further characteristics and advantages of the invention will become clearer from the description of a preferred, but not exclusive, embodiment of a monitoring device for switching systems according to the invention, illustrated by way of example in the accompanying drawings, wherein:

fig. 1 is a schematic view of a first embodiment of a monitoring device for a switching system according to the invention;

fig. 2 is a schematic view of a second embodiment of a monitoring device for a switching system according to the invention;

FIG. 3 shows an AVD (acceleration, velocity, displacement) diagram for opening and closing operations;

FIG. 4 shows a graph for determining contact travel measurements and possible contact wear;

FIG. 5 shows a graph of impact detection using threshold frequency values.

Detailed Description

With reference to fig. 1 and 2, in its more general definition, the monitoring device 1, 15 according to the present invention is suitable for monitoring a switching system 100 (for example a medium voltage circuit breaker), the switching system 100 generally comprising a contact assembly 10 having at least one movable contact and a kinematic chain 11 for actuating said movable contact and opening/closing said contact assembly 10.

The structure of the contact assembly 10 and the kinematic chain 11 may vary according to the type of switching unit and the range of voltages used, but for the purpose of the present invention they may be of conventional type and will not be described in further detail.

One characteristic feature of the monitoring device 1, 15 according to the invention is given by the fact that: the monitoring device comprises at least one accelerometer 2 positioned on the moving part of the switch system 100 and capable of determining acceleration data 3 of the moving part to which the accelerometer is attached. The accelerometer may be of a conventional type and its function (e.g. technology type, measurement range, sensitivity, number of axes, bandwidth, etc.) may be selected as desired.

Even though the accelerometer 2 may in principle be positioned on any moving part of the switching unit 100 (e.g. also on the moving contact), it is largely preferred to position it on the kinematic chain 11 between the actuator and the moving contact.

The acceleration data 3 detected by the accelerometer 2 are sent to a control unit comprising a first processing unit 4 adapted to receive said acceleration data 3 measured by said accelerometer 2 and to calculate timed instants of a predetermined event 5 and a kinetic parameter 6 related to said switching system 100. The second processing unit 7 is then adapted to receive the timed instants 5 of the predetermined event and said kinetic parameters 6 and to calculate the electrical/mechanical parameters 8 of said switching system 100 using at least one timed instant and at least one kinetic parameter.

For example, referring to fig. 3, accelerometer data 3 detected by the accelerometer 2 during open and close operations may be used to determine an AVD map for contact opening/closing based on integration and double integration of the signal. The instant of opening/closing of the contacts (time-localized event) can be seen in the acceleration diagram and in the strong variations of the speed, while the speed and position of the contacts at this instant (motion parameters) can be read from the other diagrams.

The device of the invention can therefore be used to analyze the state of the switching unit and to calculate the value of its electrical/mechanical parameters.

For example, referring to FIG. 4, contact wear due to arc erosion material may be detected by comparing contact travel curves over time. By measuring the travel of the contact between the start of the movement and the instant of closing, any variation in travel can be determined with high precision, for example less than 1mm, as shown in the bottom graph of fig. 4. In the diagram of fig. 4, the curves have been aligned instantaneously with respect to the contact closure, so that it is possible to detect the variations in the stroke of the movable contact that may be due to contact wear.

Thus, in a first embodiment, the monitoring device of the present invention may be used to analyze the state of the switching unit with respect to its current interruption capability. Important characteristics here are the total gap length, the contact wear due to arc erosion of material and the speed at which the contacts open or close. Can be detected by analyzing the signal in order to detect the impact point of contact connection and disconnection, and then by subsequent integration or double integration of the signal. Referring to fig. 5, a given acceleration threshold (Th) and a given frequency bandwidth intersection may be used to detect a shock. Similarly, bounce of the contacts when closed may be determined.

In general, the full travel curve of the stylus may be calculated from acceleration data determined by the accelerometer. However, due to acceleration and the inherently high error accumulation after double integration, a suitable error correction method should be used.

For example, the following forms are possible:

deglitching (clipping), in which high G values outside the accelerometer measurement range are analytically reconstructed;

detrending, in which it is assumed that the speed of the system should be 0 after a given time, and then checking the final error of the calculated speed;

trip assumptions, where it is assumed that the final trip should be within a given range, and then appropriate corrections;

external reference, where an additional sensor with coarser resolution can be used to give the absolute value of the stroke, while the accelerometer will give finer resolution of the relative value of the stroke, for example by using the "open" and "close" switches already available in the circuit breaker.

In a first particular embodiment of the monitoring device of the invention, for each phase of the switching system associated with the switching system, an accelerometer is included, which is located on the moving part of each phase of said switching system and is able to determine the acceleration data of said moving part. In this case, the control unit suitably comprises a third processing unit adapted to determine differences or commonalities in behaviour between the phases. In this way, the synchronization measurement can be performed based on the impact detection instant caused by the contact connection and disconnection. This time difference of impact will give a time indication of the system asynchrony. Furthermore, using the integration of the accelerometer signals, the stroke or velocity differences of the symmetric components of the system can be compared.

In a particular embodiment of the monitoring device of the invention, since the accelerometer refers to the movement of the earth's surface measuring point, if the entire body of the circuit breaker is moving, it is necessary to calculate the movement of a particular component of the circuit breaker relative to the circuit breaker body, which may require the reference to the accelerometer to detect the movement of the circuit breaker body and thus determine the movement of the particular component within the circuit breaker.

In this case, the monitoring device 1 of the invention may suitably comprise a further accelerometer connected to the frame of said switching system 100 to determine acceleration data acquired from the overall movement of the switching system 100. The control unit then suitably comprises a fifth processing unit which uses the acceleration data acquired from the global motion to correct/compensate the acceleration data of the moving part of the switching system 100. In practice, small movements of the entire reference frame can be detected using accelerometers positioned on a theoretically fixed component of the circuit breaker, and then the movement can be subtracted from any other accelerometer positioned on a moving component within the circuit breaker to obtain the relative movement of that component with respect to the circuit breaker reference frame (this is the mechanically related movement within the system).

With reference to fig. 2, in a particular embodiment of the invention, the monitoring device 15 is provided with a plurality of accelerometers 2, 21, 22, located at different positions of the kinematic chain 11 of said switching system 100 and more generally on different moving parts of the switching unit.

The control unit then suitably comprises a fourth processing unit 9 which determines whether there is a discrepancy (disparity) indicating a change in the behaviour of the kinematic chain. In fact, in this embodiment, the fourth processing unit 9 determines whether a difference between the detected values at the various positions of the kinematic chain occurs over time, said difference being indicative of possible slack, loose connections or fatigue on the kinematic chain.

In practice, when using multiple accelerometers, two or more accelerometers may be positioned on a single kinematic chain (with the emphasis on measuring individual components that are linked together in such a way that they move together under a predefined scenario that depends on the mechanical design), and/or two or more accelerometers may be positioned on a single mechanical component of the kinematic chain at locations that are connected by a fixed connection (e.g., they should move synchronously at the same time once a driving force is applied). In this way, the monitoring of the system can be based on a comparison of the differences between the timing instants of the impacts and the impact timing instants at which the rigidly connected system should be instantaneous to detect possible loosening of the connection. This can then be cross-compared with information gathered from accelerometers located on individual mechanical components in the kinematic chain to detect whether such loosening has caused excessive forces on particular components within the mechanical chain.

The monitoring of the system can also be performed by calculating the speed and deviation from the theoretical values of the different components and comparing them with the specific stresses on the components of the system (using information collected from accelerometers located on the individual mechanical components of the kinematic chain). An increase in friction of the system can be detected and by comparing the stress on the components, the location where friction is introduced can be detected. Finally, by comparison of the signals in the frequency domain, it is possible to identify the specific eigen-frequency connected to a specific oscillation and the damping variations of these parameters to be detected. In addition, the relative phase difference at several points along the connecting member can be used to detect deviations in the system, such as changes in friction/mass in the bearings, etc., which can result in changes in the relative phase, i.e., oscillation modes. In general, the information collected by the acceleration data of the kinematic chain can also be analyzed by different mechanical parts of the switching unit, by extracting the features of the AVD signal and analyzing it. By tracking changes in these characteristics (e.g., frequency or attenuation of vibrations), different components of the mechanical system, such as springs, shafts, or dampers, may be analyzed.

Therefore, the monitoring device of the present invention can improve the reliability of the switching unit by informing a user that a mechanical part whose failure may have an influence on the main function of the switching unit is operating poorly or has failed, thereby preventing more serious failure and damage.

It is noted that an advantage of the monitoring device of the invention may be an embedded system which automates the installation process of the switching unit without the need for special measurement settings. Finally, on-line measurement data from the field circuit breaker at each opening or closing operation can aid in additional research and development to optimize and design new mechanical systems for the switching unit.

From the above, it is clear that the monitoring device of the present disclosure has many advantages over conventional monitoring devices. With respect to prior art systems implementing accelerometers to measure mechanical parameters based on indirect measurement of vibration at a fixed point, the device according to the present invention directly measures the acceleration (and therefore the velocity and position) of some of the components of the kinematic chain, thereby providing more information about the mechanical system. Such direct measurement makes it more robust to changes in mechanical properties (e.g. due to temperature changes), installation location of the switch unit and similar environmental issues. Another advantage over prior art systems for measuring travel curves and speeds is generally lower cost and complexity due to:

the cost of the electronics itself is lower due to recent developments in the field of accelerometers;

-it can be included in the switch unit by default or sold separately to the customer;

low maintenance costs and low complexity of such a system, since it will be attached as an accessory to a mechanical part, not part of the mechanical system itself, which means:

a) a failure of the device does not in any way impede further operation of the switching unit, but only impedes monitoring;

b) the device itself is easily replaceable.

Finally, as already mentioned, the device of the invention allows continuous measurement on-site and on-line, with the consequent advantages of safety and reliability of the switching system (always controlled) and of collecting data for further development.

The following advantages and advantages may be more pronounced with respect to prior art systems when multiple accelerometers are used:

service assistance for setting a circuit breaker: the benefit lies in the fact that the multiple accelerator system included in the circuit breaker can be used early in the manufacturing process and also during both factory and field testing (e.g., during major repairs) to inform the circuit breaker setup personnel in real time of possible phase symmetries or asymmetries, and also to give instructions or guidance (e.g., number of turns of pushrod connections) to improve this required step. Since it is not necessary to install and detach an external measuring device, an initial process of setting the circuit breaker can be accelerated and service is easy. In addition, some measurement devices are not removed correctly after testing, which may present an additional risk of failure.

-simultaneous measurement of in-line contacts: the benefit is constant information about the system state and will assist service during maintenance or even trigger service if the symmetry is outside the specified range. With regard to the possibility of synchronizing the switches, there is also provided the possibility of operating the circuit breaker in such a way that all three contacts are exhausted in an optimal manner.

-determining on-line the loose mechanical connection or system elasticity: the benefit is that once the mechanical connection is broken or loosened for any other reason, automatic service will be triggered before this causes further damage. The service will be directed to the failed component and the process will be faster. It also allows spare parts/replacement parts needed for service to be scheduled, reducing the time required for maintenance.

-online measurement of breaker movement during operation: the benefit is that constant information about the state of the infrastructure where the circuit breaker is installed and will assist service during maintenance or even trigger service to check installation if the circuit breaker starts to move (jump) too much during operation. It also allows improved measurements of the circuit breaker components since the overall motion of the circuit breaker cannot be distinguished from the components of the circuit breaker.

Numerous variants can be made to the monitoring device thus conceived, all falling within the scope of the appended claims. In practice, the materials used, as well as the contingent dimensions and shapes, may be any according to requirements and to the state of the art.