Circuit breaker with advanced health diagnosis

Abstract

A diagnostic system for monitoring a mechanical trip mechanism of a circuit interrupter provides advanced diagnostics. The trip mechanism includes a D-axis actuated by the trip unit, an operating mechanism actuated by the D-axis, and a polar axis actuated by the operating mechanism to physically separate the separable contacts. During each turn-off operation, the diagnostic system determines the time elapsed between the start of movement of the D-axis to its turn-off position and the arrival of the polar axis to its turn-off position in order to detect degradation of the trip mechanism as early as possible. This ensures that poor performance can be detected even if the trip mechanism meets the lowest acceptable performance requirements. Prior to complete failure of the trip mechanism, the user is notified once the performance is degraded to a worry level, thereby saving a large amount of time and resources and preventing more extensive damage.

Description

Technical Field

[0001] The disclosed concept relates generally to circuit interrupters and, in particular, to a monitoring system for tracking performance degradation in a mechanical trip mechanism of a circuit interrupter. Background Art

[0002] Circuit interrupters, such as but not limited to circuit breakers, are commonly used to protect circuits from damage due to various tripping conditions, including overcurrent conditions such as overload conditions, short circuits, or other fault conditions such as arc faults or ground faults. Figure 1 A circuit interrupter, such as the schematically depicted circuit interrupter 1, is typically configured to be electrically connected between a power source 2 and a load 3 via line and neutral conductors 4, 6. The circuit interrupter typically includes separable electrical contacts 8 that operate as a switch. When the separable contacts 8 are in contact with each other and in a closed state, current can flow through any circuit connected to the circuit interrupter. When the separable contacts 8 are separated from each other and in an open state, current cannot flow through any circuit connected to the circuit interrupter. Typically, the circuit interrupter includes: a mechanical trip mechanism 10, which is designed to quickly open or close the separable contacts 8; and a trip monitoring mechanism, such as an electronic trip unit 12, which uses a current sensor 14 or other type of sensor to detect a variety of fault conditions. When a fault condition is sensed, the trip unit 12 is configured to instruct the mechanical trip mechanism 10 to trip and open the separable contacts 8.

[0003] Typically, one of the separable contacts 8 is fixed in place and remains stationary, while the other separable contact 8 is part of a movable wire assembly. When the trip unit 12 detects a fault condition and initiates a disconnection operation by instructing the mechanical trip mechanism 10 to disconnect the separable contacts 8, the mechanical trip mechanism 10 disconnects the separable contacts 8 by driving the movable wire assembly away from the stationary separable contact. The mechanical trip mechanism 10 needs to be able to quickly drive the movable wire assembly away from the fixed separable contact to mitigate the effects of the fault condition.

[0004] Existing circuit breakers generally provide limited information about the wear of various component mechanisms, such as the mechanical trip mechanism 10 or any of its subcomponents. Operators generally have very limited knowledge of whether the mechanical trip mechanism 10 has degraded and requires maintenance until the mechanical trip mechanism 10 significantly slows down or fails completely. In addition, the mechanical trip mechanism 10 includes multiple components, each of which may degrade at a different rate relative to the other components. When the mechanical trip mechanism 10 fails to operate accurately, the lack of prior notification of the failure may make the maintenance of the mechanical trip mechanism 10 time-consuming and inefficient.

[0005] Therefore, there is room for improvement in monitoring systems for mechanical trip mechanisms in circuit interrupters. Summary of the invention

[0006] These needs and others are met by a monitoring system that provides advanced diagnostics for the mechanical trip mechanism of a circuit interrupter. The monitoring system monitors performance during each disconnect operation to detect degradation of the mechanical trip mechanism as early as possible. Monitoring each disconnect operation ensures that even if the mechanical trip mechanism meets minimum acceptable operating performance requirements, the system will immediately notice when performance is poor and can notify the user if performance degrades to a concerning level before the mechanical trip mechanism fails completely. Prompting the user to inspect and repair the mechanical trip mechanism before a failure occurs can save considerable time and resources and prevent further damage, compared to waiting until the mechanism actually fails.

[0007] According to one aspect of the present disclosure, there is provided a circuit interrupter configured to be electrically connected between a power source and a load, comprising: a pair of separable contacts, including a stationary contact and a moving contact arranged between the power source and the load; a trip unit configured to detect a trip condition; a mechanical trip mechanism; and a diagnostic system. The mechanical trip mechanism comprises: a D-axis configured to be actuated by the trip unit; an operating mechanism configured to be actuated by the D-axis; and a pole axis configured to be actuated by the operating mechanism and to move the moving contact between a closed position and an open position. The diagnostic system comprises: a D-axis sensor configured to be coupled to the D-axis and to track the position of the D-axis; a pole axis sensor configured to be coupled to the pole axis and to track the position of the pole axis; and a microprocessor in electrical communication with the D-axis sensor and the pole axis sensor. For each disconnect operation of the circuit interrupter, the microprocessor is configured to: time stamp a first time when the D-axis moves to its disconnected position; time stamp a second time when the pole shaft moves to its disconnected position; determine a mechanism execution time of the mechanical trip mechanism by subtracting the first time from the second time; transmit the mechanism execution time to the trip unit; and determine whether the circuit interrupter requires maintenance based on the mechanism execution time.

[0008] According to another aspect of the disclosed concept, a method for monitoring the performance of a mechanical trip mechanism during an opening operation of a circuit interrupter is provided, comprising: positioning a D-axis sensor to track the position of a D-axis of a mechanical trip mechanism; positioning a polar axis sensor to track the position of a polar axis of a mechanical trip mechanism; using a microprocessor to time stamp a first time that the D-axis moves to its opening position; using a microprocessor to time stamp a second time that the polar axis moves to its opening position; using a microprocessor to subtract the first time from the second time to determine a mechanism execution time of the mechanical trip mechanism; and using a trip unit of the circuit interrupter, determining whether the circuit interrupter requires maintenance based on the mechanism execution time. The D-axis is configured to be actuated by the trip unit when the trip unit detects a trip condition, the operating mechanism of the mechanical trip mechanism is configured to be actuated by the D-axis, the polar axis is configured to be actuated by the operating mechanism, and the polar axis is configured to open separable contacts of the circuit interrupter.

[0009] According to another aspect of the disclosed concept, a diagnostic system for monitoring the performance of a mechanical trip mechanism of a circuit breaker is provided, which includes a D-axis sensor, a polar axis sensor, and a microprocessor in electrical communication with the D-axis sensor and the polar axis sensor. The mechanical trip mechanism includes: a D-axis configured to be actuated by a trip unit; an operating mechanism configured to be actuated by the D-axis; and a polar axis configured to be actuated by the operating mechanism and to separate a moving separable contact from a stationary separable contact. The D-axis sensor is configured to be fixedly positioned near the D-axis and track the position of the D-axis, and the polar axis sensor is configured to be fixedly positioned near the polar axis and track the position of the polar axis. For each disconnection operation of the circuit breaker, the microprocessor is configured to: time-stamp a first time that the D-axis moves to its disconnected position; time-stamp a second time that the polar axis moves to its disconnected position; determine a mechanism execution time of the mechanical trip mechanism by subtracting the first time from the second time; transmit the mechanism execution time to the trip unit; and determine whether the circuit breaker needs maintenance based on the mechanism execution time. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention may be best understood from the following description of the preferred embodiments when read in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a schematic diagram of a circuit interrupter;

[0012] Figure 2 According to an exemplary embodiment of the present disclosure, a method for monitoring Figure 1 A schematic diagram of a diagnostic system for a mechanical trip mechanism depicted in;

[0013] Figure 3 is an isometric view of the exterior of a 3-pole circuit interrupter according to an exemplary embodiment of the disclosed concepts;

[0014] Figure 4 According to the exemplary embodiment of the present disclosure, Figure 3 A side view of a circuit interrupter shown in , depicting the circuit interrupter in a closed state;

[0015] Figure 5 According to the exemplary embodiment of the present disclosure, Figure 3 An alternative side view of a circuit interrupter shown in FIG. Figure 4 Certain components shown in FIG. Figure 4 some components not shown in the figure, and wherein the circuit interrupter is depicted shortly after the disconnection operation is initiated;

[0016] Figure 6 The exemplary embodiment according to the present disclosure is shown. Figure 5 , which depicts the circuit interrupter in an open state after completing a disconnect operation; and

[0017] Figure 7 is a flow chart of a method of monitoring performance of a mechanical trip mechanism of a circuit interrupter according to an exemplary embodiment of the disclosed concept. DETAILED DESCRIPTION

[0018] Directional phrases used herein (eg, left, right, front, rear, top, bottom and their derivatives) relate to the orientation of elements as shown in the drawings and shall not limit the claims unless explicitly recited herein.

[0019] As used herein, the statement that two or more parts are "coupled" together means that the parts are either coupled together directly or coupled together through one or more intermediate parts.

[0020] As used herein, when ordinal terms such as “first” and “second” are used to modify nouns, such usage is intended only to distinguish one item from another and is not intended to require a sequential order unless specifically stated.

[0021] As used herein, the term "plurality" refers to one or an integer greater than one (ie, more).

[0022] As used herein, the term "processor" refers to a programmable analog and / or digital device that can store, retrieve, and process data; a controller; a control circuit; a computer; a workstation; a personal computer; a microprocessor; a microcontroller; a microcomputer; a central processing unit; a mainframe computer; a minicomputer; a server; a networked processor; or any suitable processing device or apparatus.

[0023] Reference now Figure 2 , according to an exemplary embodiment of the present disclosure, more detailed and schematically depicts Figure 1 A mechanical trip mechanism 10 is depicted in FIG. 8 , and a diagnostic system 30 for monitoring the performance of the mechanical trip mechanism 10 is schematically depicted. Figures 3 to 6 Shown in Figure 1 Various isometric views of a circuit interrupter 1 schematically depicted in FIG. Figure 2 Combination Figures 3 to 6 The mechanical trip mechanism 10 and the disclosed diagnostic system 30 are described. Figure 2 The schematic diagram in FIG. 1 is used to provide a simplified depiction of the interaction between the various components of the mechanical trip mechanism 10 and the various components of the diagnostic system 30. This is because the circuit interrupter 1 includes many overlapping components, which makes it difficult to understand even when using Figures 3 to 6 In the isometric view, it is also difficult to visually discern the interactions between the various components.

[0024] Circuit breaker 1 Figures 3 to 6 3-pole circuit breaker is shown in FIG. Figure 3 As shown in the figure, each of the three individual poles may be represented by a unique reference numeral 20A, 20B, or 20C. In addition, these poles may be collectively referred to as poles 20, and any one of these poles may be generally referred to as pole 20. Figure 3 All three poles 20 are shown, but it should be noted that Figures 4 to 6 Several features of two of the poles 20 are hidden to make the features of the visible pole 20 more easily discernible. It should be understood that the hidden features of the other two poles are functionally similar to those of the Figures 4 to 6 The features are the same as shown in .

[0025] Figure 3 The three-pole circuit interrupter 1 is shown with the outer housing complete. Figure 4 and Figure 5 Both show a side view of a circuit interrupter 1 with most of the outer casing removed, wherein Figure 4 The circuit interrupter 1 is depicted in a closed state, i.e. a state in which the separable contacts 8 are closed, and Figure 5 The circuit interrupter 1 is depicted shortly after a disconnect operation has begun to open the separable contacts 8 from a closed state. As further detailed later herein, Figure 4 and Figure 5 Many of the same components are shown, but Figure 4 and Figure 5 Each of the figures also shows and hides some components that are not shown or hidden in other figures. Figure 6Also shown is a side view of the circuit interrupter 1 with most of the outer housing removed and depicting the circuit interrupter 1 in an open state, i.e., a state in which the separable contacts 8 are open due to separation during a disconnect operation. Figure 3 , Figure 4 , Figure 5 and Figure 6 A manual disconnect mechanism 18 is marked in each of the figures in the drawings and can be used to determine the orientation of each of the figures relative to each other. When the circuit interrupter 1 needs to be taken out of service for any reason (e.g., for maintenance), the manual disconnect mechanism 18 is used to manually disconnect the separable contacts 8.

[0026] Now combine Figure 2 A detailed description of the function of the mechanical trip mechanism 10 will be provided later. Figures 4 to 6 The functions of the diagnostic system 30 are described in further detail in FIG. Figure 2 In the embodiment, the separable contact 8 includes a moving contact 15 and a stationary contact 17. The mechanical trip mechanism 10 includes a D-axis 22, an operating mechanism 24 operably connected to the D-axis 22, and a pole shaft 26 operably connected to the operating mechanism 24. The D-axis 22 and the pole shaft 26 are also Figures 4 to 6 When the operating condition in the circuit interrupter 1 is normal, the separable contacts 8 are closed so that power can flow between the power source 2 and the load 3. The position of the D-axis 22 when the separable contacts 8 are closed can be referred to as the closed position of the D-axis 22, and the position of the pole shaft 26 when the separable contacts 8 are closed can be referred to as the closed position of the pole shaft 26.

[0027] When a trip condition is detected, the trip unit 12 sends a signal that causes the mechanical trip mechanism 10 to disconnect the separable contact 8. Specifically, the signal sent by the trip unit 12 initiates the rotation of the D shaft 22 in a first direction (e.g., clockwise or counterclockwise), which can be referred to as the disconnecting direction of the D shaft. The operating mechanism 24 is an assembly including a plurality of mechanical components, and the rotation of the D shaft 22 in its disconnecting direction causes the operating mechanism 24 to rotate the pole shaft 26 in the first direction (e.g., clockwise or counterclockwise), which can be referred to as the disconnecting direction of the pole shaft. The pole shaft 26 is operably coupled to the moving contact 15, and the rotation of the pole shaft 26 in its disconnecting direction causes the moving contact 15 to be physically separated from the stationary contact 17. The position of the D shaft 22 when the separable contact 8 is disconnected can be referred to as the disconnecting position of the D shaft 22, and the position of the pole shaft 26 when the separable contact 8 is disconnected can be referred to as the disconnecting position of the pole shaft 26.

[0028] Reference now Figure 2 In the electronic trip unit 12, it should be noted that the circuit interrupter 1 also includes a test trip function, which is common for circuit interrupters. Figure 2As shown in , the trip test function is included in the trip unit 12 as a trip test controller 21. It should be understood that the test trip controller 21 enables a user to initiate a simulation of a trip condition to test the performance of the mechanical trip mechanism 10. The test trip controller 21 may include, for example but not limited to, a button on the outside of the circuit interrupter 1 that the user can actuate by pressing the button. It should be noted that the same sequence of steps detailed above for disconnecting the separable contacts 8 using the mechanical trip mechanism 10 in a trip condition also applies to the case where a test trip is initiated by the test trip controller 21. It should also be noted that the manual disconnect mechanism 18 is actuated to initiate the rotation of the D shaft 22 in its disconnecting direction, and the remaining steps of the sequence detailed above also apply to the case where the disconnect operation is initiated by actuating the manual disconnect mechanism 18.

[0029] When it is necessary to reclose the separable contacts 8, the trip unit 12 sends a signal that initiates the rotation of the D shaft 22 in a second direction, which can be referred to as the closing direction of the D shaft 22, i.e., a direction opposite to the opening direction of the D shaft 22. The rotation of the D shaft 22 in its closing direction causes the operating mechanism 24 to rotate the pole shaft 26 in a second direction, which can be referred to as the closing direction of the pole shaft 26, i.e., a direction opposite to the opening direction of the pole shaft 26. The rotation of the pole shaft 26 in its closing direction causes the moving contact 15 to move toward the stationary contact 17 until the moving contact 15 and the stationary contact 17 are closed (i.e., physically contacted with each other), so that power can flow through the contacts 15, 17.

[0030] Still reference Figure 2 And also refer to Figures 4 to 6 , the diagnostic system 30 will now be described. The diagnostic system 30 includes a D-axis sensor 32, a D-axis movement detection component 33, a polar axis sensor 34, a polar axis movement target component 35, and a microprocessor 36 (in Figures 4 to 6 Not visible in and only available in Figure 2 ), wherein the microprocessor 36 is configured to receive the output of the D-axis sensor 32 and the output of the polar axis sensor 34. It should be noted that the polar axis sensor assembly 34 includes a plurality of individual sensors 34A fixed to a bracket 34B. Figures 4 to 6 34A, but the polar axis sensor assembly 34 may include fewer or more than three individual sensors 34A without departing from the scope of the disclosed concept. In an exemplary embodiment of the disclosed concept, the microprocessor 36 is a component of the trip unit 12. A D-axis sensor mounting bracket 37 is included in the circuit interrupter 1 to hold the D-axis sensor 32 and its accompanying circuit assembly in place. As previously mentioned, Figure 4 Shown in Figure 51, and one of the components is the polar axis sensor housing 38 included in the circuit interrupter 1 to hold the polar axis sensor assembly 34 and its accompanying circuitry in place. It should be noted that the polar axis 26 is Figure 4 is blocked by the polar axis sensor housing 38, but in Figure 5 and Figure 6 Visible in.

[0031] Figure 4 The circuit interrupter 1 is shown when the separable contacts 8 are fully closed, and Figure 5 The circuit interrupter 1 is shown shortly after the opening operation has begun, as can be seen from Figure 4 and Figure 5 The slight difference in the position of the interlocking arm 41 between Figure 4 and Figure 5 The slight difference in the position of the opening and closing spring arms 42 can be seen. Figure 6 The circuit interrupter 1 is shown when the separable contacts 8 are fully opened (ie, when the movable contact 15 is caused to travel its maximum travel distance). When the separable contacts 8 are closed, the interlock arm 41 and the opening and closing spring arm 42 are arranged at Figure 4 After the disconnection operation begins, the interlock arm 41 is in the position shown in FIG. Figure 4 Continue in the direction indicated by arrow 43 until you reach Figure 6 and the opening and closing spring arm 42 is in the position shown in Figure 4 Continue in the direction indicated by arrow 44 until you reach Figure 6 The location shown in .

[0032] First, it should be noted that the D-shaft 22 includes a flat circular head, and the circular head is the D-shaft 22. Figures 4 to 6 Therefore, although Figure 6 The D axis 22 is plotted relative to Figure 4 and Figure 5 Circuit breaker 1 after rotation, but from Figures 4 to 6The rotation of the D-axis 22 cannot be seen in the view shown in the figure because the rotation axis of the D-axis 22 coincides with the center of the flat circular head. The D-axis sensor 32 is an inductive sensor, and the D-axis movement detection assembly 33 includes a metal target. The D-axis 22 is operably connected to a micro switch (not visible in the figure), and the D-axis movement detection assembly 33 is also operably connected to the micro switch. It should be noted that the micro switch is configured to be connected along a power flow path and is configured to switch between a first state and a second state, so that when the micro switch is arranged in the first state, power can flow through the micro switch along a first path, and when the micro switch is arranged in the second state, power can flow through the micro switch along a second path different from the first path. In the circuit interrupter 1, the micro switch is connected along the power flow path, and the micro switch is positioned relative to the D-axis 22 so that the rotation of the D-axis 22 in the disconnecting direction (i.e., from the D-axis closed position to the D-axis open position) actuates the micro switch to switch from the first state to the second state. The metal target of the D-axis movement detection assembly 33 is operably connected to the micro switch, so that the change in the state of the micro switch caused by the rotation of the D-axis 22 in its disconnecting direction causes the signal output by the metal target to change. The output change of the metal target of the detection assembly 33 disturbs the electromagnetic field of the D-axis sensor 32 and causes the D-axis sensor 32 to generate an output, which is received by the microprocessor 36.

[0033] Polar axis sensor 34 is also an inductive sensor, and polar axis mobile target assembly 35 also includes a metal target. Polar axis mobile target assembly 35 is fixedly coupled to polar axis 26 so that rotation of polar axis 26 from its closed position to its open position causes corresponding movement of mobile target assembly 35 (including the metal target). Movement of the metal target disturbs the electromagnetic field of polar axis sensor 34 and causes sensor 34 to generate an output, which is received by microprocessor 36.

[0034] It should be understood that the trip unit typically includes multiple microprocessors and controllers dedicated to different functions. The microprocessor 36 may be referred to as the diagnostic microprocessor 36 of the trip unit, while a separate microprocessor (not numbered or shown in the drawings) is used to monitor the trip condition of the circuit interrupter 1. The various microprocessors and controllers of the trip unit 12 are in electrical communication with each other so that the diagnostic microprocessor 36 can be notified when the trip unit 12 begins to trip, and so that the diagnostic microprocessor 36 transmits the data it receives from the D-axis sensor 32 and the polar axis sensor 34 to the memory of the trip unit 12.

[0035] When the circuit interrupter 1 is in use, the microprocessor 36 continuously checks the output of the D-axis sensor 32 and the output of the pole axis sensor 34. The microprocessor 36 is configured to know which reading from the D-axis sensor 32 and which reading from the pole axis sensor 34 respectively indicate that the D-axis 22 and the pole axis 26 are in the closed position (i.e., so that the separable contacts 8 are closed). The microprocessor 36 is also configured to know which reading from the D-axis sensor 32 and which reading from the pole axis sensor 34 respectively indicate that the D-axis 22 and the pole axis 26 are in the open position (i.e., so that the separable contacts 8 are open). Therefore, when the D-axis 22 begins to rotate due to the trip unit 12 initiating the trip or the manual opening operation initiating the actuation of the manual opening mechanism 18, the microprocessor 36 is able to detect when the D-axis 22 begins to rotate away from its closed position based on the change in the output of the D-axis sensor 32. In addition, the microprocessor 36 is able to detect when the pole axis 26 reaches its open position. The microprocessor 36 timestamps the time when the D-shaft 22 begins to rotate toward its open position and timestamps the time when the pole shaft 26 reaches its open position. The microprocessor 36 then calculates the time that has passed between these two timestamps, which may be referred to as the "mechanism execution time" of the circuit interrupter 1 within a given opening operation.

[0036] The microprocessor 36 communicates the mechanism execution time to the memory of the trip unit 12. As used herein, the term "functional failure" is used to indicate that the mechanical trip mechanism 10 is still able to open the separable contacts 8, but the mechanism execution time is unacceptably slow. After the mechanism execution time is received in the memory of the trip unit 12, the trip unit 12 compares the mechanism execution time with a predetermined acceptable time limit, wherein the mechanism execution time exceeds the predetermined time limit to indicate a functional failure. If the mechanism execution time exceeds the predetermined time limit, the trip unit 12 sends a signal to the user interface (which can be located locally in the circuit interrupter 1 or remotely, or both) to indicate that the mechanical trip mechanism 10 needs to be taken out of operation and repaired before it can be operated again. In addition, the trip unit 12 stores each mechanism execution time received and maintains a log of all received mechanism execution times so that each new mechanism execution time can be compared with the previous mechanism execution time to determine whether there is a trend of performance degradation.

[0037] However, if the mechanism execution time does not exceed the predetermined time limit, the trip unit 12 compares the mechanism execution time with the previously stored mechanism execution time using a pre-programmed set of parameters. If the latest mechanism execution time differs sufficiently from one or more of the previous mechanism execution times, or if there is a sufficiently significant deterioration trend in the latest few mechanism execution times, the trip unit 12 sends a signal to the user interface indicating that the mechanical trip unit 10 is on the verge of failure and recommends maintenance. It should be understood that repairing the mechanical trip unit at this stage (i.e., before a functional failure occurs) may take less time and resources than repairing the mechanical trip unit 10 after a functional failure occurs because the damage is less likely to become more serious or extensive. The trip unit 12 can also be configured to transmit the stored mechanism execution time to a data cloud so that trends between circuit interrupters 1 of the same or similar models can be identified. It is expected that the mechanism execution time is most likely to reflect the performance of the operating mechanism 24, rather than the performance of the D-shaft 22 or the pole shaft 26, because the D-shaft 22 and the pole shaft 26 are relatively simple components with less chance of degradation or damage, while the operating mechanism 24 is a relatively more complex component.

[0038] Figure 7 is a flow chart of a method for monitoring the performance of a mechanical trip mechanism during an opening operation of a circuit breaker according to an exemplary embodiment of the present disclosure. Figure 7 The method in can be used Figures 1 to 6 The diagnostic system 30 and the mechanical trip mechanism 10 shown in FIG. Figures 1 to 6 However, it should be understood that the method may be used with other devices without departing from the scope of the disclosed concept.

[0039] The method 100 begins at step 101, in which the metal target of the D-axis movement detection assembly 33 is coupled to the circuit interrupter 1 and positioned to change its output signal based on the movement of the D-axis 22, and in which the metal target of the polar axis movement target assembly 35 is coupled to the circuit interrupter 1 and positioned to move proportionally relative to the movement of the polar axis 26. Positioning the metal target of the D-axis movement detection assembly 33 to change its output signal based on the movement of the D-axis 22 may include, for example but not limited to, operably connecting the D-axis 22 to a micro switch, and also operably connecting the metal target of the D-axis movement detection assembly 33 to the micro switch, so that rotation of the D-axis 22 will change the state of the micro switch, and so that the change in the state of the micro switch causes the signal output by the metal target of the D-axis movement detection assembly 33 to change. Positioning the metal target of polar axis moving target assembly 35 to change its output signal based on movement of polar shaft 26 may include, for example, but not limited to, fixedly coupling polar axis moving target assembly 35 to polar shaft 26 such that rotation of polar shaft 26 from its closed position to its open position causes corresponding movement of moving target assembly 35 (including the metal target).

[0040] At step 102, the inductive D-axis sensor 32 is fixedly positioned in the circuit interrupter 1 close enough to the D-axis movement detection assembly 33 so that the D-axis sensor 32 can detect the output change of the metal target of the D-axis movement detection assembly 33. In addition, the inductive polar axis sensor 34 is fixedly positioned in the circuit interrupter 1 close enough to the polar axis moving target assembly 35 so that the polar axis sensor 34 can detect the movement of the metal target of the polar axis moving target assembly 35. At step 103, the microprocessor 36 begins to continuously monitor the position of the D-axis 22 and the position of the polar axis 26, for example, by continuously reading the output of the D-axis sensor 32 and the output of the polar axis sensor 34. At step 104, the microprocessor 36 timestamps the time when the D-axis 22 begins to rotate away from its closed position, and then timestamps the time when the polar axis 26 reaches its open position.

[0041] Continue to refer Figure 7At step 105, the microprocessor 36 determines the mechanism execution time by calculating the time elapsed between the D-shaft 22 reaching its open position and the pole shaft 26 reaching its open position using the timestamp generated at step 104, and transmits the mechanism execution time to the memory of the trip unit 12, which stores the mechanism execution time in a data log. At step 106, the trip unit 12 compares the mechanism execution time with a predetermined acceptable time limit. If the mechanism execution time exceeds the predetermined acceptable time limit, the method 100 proceeds to step 107, in which the trip unit 12 issues a message notifying the user that the mechanical trip mechanism 10 has failed in function and needs to be taken out of operation and repaired before it can be operated again.

[0042] If it is determined at step 106 that the mechanism execution time does not exceed the predetermined acceptable time limit, the method 100 proceeds to step 108 and compares the current mechanism execution time with the previous mechanism execution time stored in the data log. At step 109, the trip unit 12 uses a pre-programmed set of parameters to determine the extent to which the mechanical trip mechanism 10 is tending to have an unacceptable mechanism execution time. If the mechanism execution time analyzed according to the pre-programmed parameters is deemed too prone to failure, the method proceeds to step 110 and the trip unit 12 notifies the user that maintenance is recommended due to the deterioration of the performance of the mechanical trip mechanism 10. If the mechanism execution time analyzed according to the pre-programmed parameters does not have a tendency to fail, the method returns to step 103.

[0043] In addition to preventing damage from becoming more severe or more extensive by identifying performance degradation of the mechanical trip mechanism 10 before a functional failure occurs, the diagnostic system 30 and method 100 disclosed herein also provide other improvements to existing performance monitoring systems. Specifically, existing performance monitoring systems for mechanical trip mechanisms generally rely on monitoring the current flowing through the circuit interrupter 1 to determine when the separable contacts 8 are actually opened, thereby determining how the performance of the mechanical trip mechanism 10 is. Compared with the diagnostic system 30 and method 100 disclosed herein, relying on the flow of current to determine when the separable contacts 8 are opened is significantly less accurate for determining the performance of the various components of the mechanical trip mechanism 10. In addition, the diagnostic system 30 and method 100 disclosed herein can be used to determine the performance of the mechanical trip mechanism 10 even when there is no current flowing through the circuit interrupter 1, such as during a test trip performed by the test trip controller 21, or during the opening of the separable contacts 8 by manual actuation of the manual opening mechanism 18.

[0044] Although the specific embodiments of the present invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and substitutions may be made to these details in accordance with the overall teachings of the present disclosure. Therefore, the specific arrangements disclosed are intended only to illustrate and do not limit the scope of the present disclosure, which shall be given by the full scope of the appended claims and any and all equivalents thereof.

Claims

1. A circuit breaker configured to be electrically connected between a power source and a load, the circuit breaker comprising: a pair of separable contacts, including a stationary contact and a moving contact arranged between the power source and the load; a trip unit configured to detect a trip condition; A mechanical tripping mechanism, the mechanical tripping mechanism comprising: A D-axis configured to be actuated by the trip unit; an operating mechanism configured to be actuated by the D-axis; and a pole shaft configured to be actuated by the operating mechanism and to move the movable contact between a closed position and an open position; and A diagnostic system for monitoring the performance of the mechanical trip mechanism, the diagnostic system comprising: a D-axis sensor configured to track a position of the D-axis; a polar axis sensor configured to track the position of the polar axis; and a microprocessor in electrical communication with the D-axis sensor and the polar-axis sensor, and the microprocessor is configured to continuously read the D-axis sensor and the polar-axis sensor when the circuit interrupter is in use, Wherein, for each disconnection operation of the circuit breaker to move the movable contact from the closed state to the open state, the microprocessor is configured to: Based on the output of the D-axis sensor, a time stamp is recorded for the first time when the D-axis starts to move toward the disconnected position, Based on the output of the polar axis sensor, a second time when the polar axis reaches the disconnected position is time stamped and recorded, determining a mechanism execution time of the mechanical trip mechanism by subtracting the first time from the second time, transmitting the mechanism execution time to the trip unit, and A determination is made whether the circuit interrupter requires maintenance based on the mechanism execution time.

2. The circuit breaker according to claim 1, in, the microprocessor being configured to transmit the mechanism execution time to a memory of the trip unit, wherein the trip unit is configured to compare the mechanism execution time with a predetermined time limit after receiving the mechanism execution time, Wherein, the trip unit is configured to notify a user that the mechanical trip mechanism requires maintenance if the execution time of the mechanism exceeds the predetermined time limit.

3. The circuit breaker according to claim 2, in, When the trip unit receives the mechanism execution time, the trip unit identifies the mechanism execution time as the current mechanism execution time. wherein the trip unit is configured to store a previous mechanism execution time associated with a previous disconnecting operation, wherein the trip unit is configured to compare the current mechanism execution time with the stored previous mechanism execution time to determine whether the mechanical trip mechanism has a tendency to fail, Wherein, the trip unit is configured to notify a user that maintenance of the mechanical trip mechanism is recommended if the trip unit determines that there is a trend of failure.

4. The circuit interrupter of claim 1, further comprising: a manual disconnect mechanism operably connected to the mechanical trip mechanism and configured to enable a user to manually initiate a disconnect operation, wherein the trip unit comprises a test trip controller configured to be actuated by a user to simulate a trip condition that initiates a disconnect operation, Wherein, the diagnostic system is configured to determine the mechanism execution time regardless of whether a given disconnect operation is initiated due to: the trip unit detecting an actual trip condition, actuation of the test trip controller, or actuation of the manual disconnect mechanism.

5. The circuit interrupter of claim 1, wherein: The diagnostic system further comprises: a D-axis metal target positioned so that movement of the D-axis causes a change in a signal output by the D-axis metal target; and a polar axis metal target positioned so that movement of the polar axis causes a corresponding movement of the polar axis metal target, wherein the D-axis sensor is an inductive sensor, and wherein the D-axis sensor is positioned such that the change in the signal output by the D-axis metal target changes the electromagnetic field of the D-axis sensor and causes the D-axis sensor to generate a D-axis position output, and Wherein the polar axis sensor is an inductive sensor, and wherein the polar axis sensor is positioned such that movement of the polar axis metal target changes the electromagnetic field of the polar axis sensor and causes the polar axis sensor to generate a polar axis position output.

6. The circuit interrupter according to claim 1, in, The diagnostic system is configured to determine when the mechanism is actuated regardless of whether current is flowing through the circuit interrupter.

7. A method of monitoring the performance of a mechanical trip mechanism during a disconnect operation of a circuit interrupter, the method comprising: positioning a D-axis sensor to track the position of a D-axis of the mechanical trip mechanism; positioning a pole axis sensor to track a position of a pole axis of the mechanical trip mechanism; when the circuit interrupter is in use, continuously reading the D-axis sensor with a microprocessor, and continuously reading the polar axis sensor with the microprocessor; Using the microprocessor to timestamp the first time when the D axis starts to move from the closed position to the open position; Using the microprocessor to timestamp and record a second time when the polar shaft reaches the disconnected position; using the microprocessor to subtract the first time from the second time to determine a mechanism execution time of the mechanical trip mechanism; as well as using a trip unit of the circuit breaker to determine whether the circuit breaker needs maintenance based on the execution time of the mechanism, wherein the D-axis is configured to be actuated by the trip unit when the trip unit detects a trip condition, wherein the operating mechanism of the mechanical tripping mechanism is configured to be actuated by the D-axis, wherein the polar axis is configured to be actuated by the operating mechanism, wherein the pole shaft is configured to disconnect separable contacts of the circuit interrupter, wherein the separable contacts are configured to close when the D-axis is in the closed position, and are configured to open when the pole shaft is in the open position, and Wherein, the mechanism execution time can be determined regardless of whether current flows through the circuit interrupter.

8. The method according to claim 7, further comprising: transmitting the mechanism execution time to the trip unit; comparing the mechanism execution time with a predetermined time limit using the trip unit; as well as In the event that the mechanism execution time exceeds the predetermined time limit, a user is notified that the mechanical trip mechanism needs to be serviced.

9. The method according to claim 8, further comprising: Using the trip unit, identifying the received mechanism execution time as the current mechanism execution time; storing a previous mechanism execution time associated with a previous disconnect operation in a data log; comparing the current mechanism execution time with the stored previous mechanism execution time to determine if the mechanical trip mechanism is trending toward failure; as well as In the event that the trip unit determines that there is a tendency for failure to occur, a user is notified that maintenance of the mechanical trip mechanism is recommended.

10. The method according to claim 7, in, The D-axis is also configured to be actuated by a test trip control of the trip unit, the test trip control enabling a user to simulate a trip condition, wherein the D-axis is further configured to be actuated by a manual disconnect mechanism, the manual disconnect mechanism being configured to enable a user to manually initiate a disconnect operation, and The mechanism execution time can be determined regardless of whether the D axis is actuated due to: the trip unit detecting an actual trip condition, actuating the test trip controller, or actuating the manual disconnect mechanism.

11. The method according to claim 7, further comprising: positioning a D-axis metal target relative to the D-axis such that movement of the D-axis causes a change in a signal output by the D-axis metal target; as well as positioning a polar axis metal target such that movement of the polar axis causes a corresponding movement of the polar axis metal target, wherein the D-axis sensor is an inductive sensor, and wherein the change in the signal output by the D-axis metal target changes the electromagnetic field of the D-axis sensor and causes the D-axis sensor to generate a D-axis position output, and Wherein the polar axis sensor is an inductive sensor, and wherein movement of the polar axis metal target changes the electromagnetic field of the polar axis sensor and causes the polar axis sensor to generate a polar axis position output.

12. A diagnostic system for monitoring the performance of a mechanical trip mechanism of a circuit interrupter, wherein: The mechanical trip mechanism includes: a D-axis configured to be actuated by a trip unit; an operating mechanism configured to be actuated by the D-axis; and a pole shaft configured to be actuated by the operating mechanism and to separate a moving separable contact from a stationary separable contact, and the diagnostic system includes: a D-axis sensor configured to be fixedly positioned adjacent the D-axis and to track a position of the D-axis; a polar axis sensor configured to be fixedly positioned proximate the polar axis and to track the position of the polar axis; and a microprocessor in electrical communication with the D-axis sensor and the polar-axis sensor, and the microprocessor is configured to continuously read the D-axis sensor and the polar-axis sensor when the circuit interrupter is in use, Wherein, for each disconnection operation of the circuit breaker, the microprocessor is configured to: The time when the D axis starts to rotate toward the disconnected position is recorded with a timestamp, A timestamp is recorded for the second time when the polar axis reaches the disconnected position, determining a mechanism execution time of the mechanical trip mechanism by subtracting the first time from the second time, and The mechanism execution time is transmitted to the trip unit to enable the trip unit to determine whether the circuit interrupter requires maintenance based on the mechanism execution time.

13. The diagnostic system of claim 12, further comprising: a manual disconnect mechanism operably connected to the mechanical trip mechanism and configured to enable a user to manually initiate a disconnect operation, wherein the trip unit comprises a test trip controller configured to be actuated by a user to simulate a trip condition that initiates a disconnect operation, Wherein, the diagnostic system is configured to determine the mechanism execution time regardless of whether a given disconnect operation is initiated due to: the trip unit detecting an actual trip condition, actuation of the test trip controller, or actuation of the manual disconnect mechanism.

14. The diagnostic system according to claim 12, wherein: The diagnostic system further comprises: a D-axis metal target positioned so that movement of the D-axis causes a change in a signal output by the D-axis metal target; and a polar axis metal target positioned so that movement of the polar axis causes a corresponding movement of the polar axis metal target, wherein the D-axis sensor is an inductive sensor, and wherein the D-axis sensor is positioned such that the change in the signal output by the D-axis metal target changes the electromagnetic field of the D-axis sensor and causes the D-axis sensor to generate a D-axis position output, and Wherein the polar axis sensor is an inductive sensor, and wherein the polar axis sensor is positioned such that movement of the polar axis metal target changes the electromagnetic field of the polar axis sensor and causes the polar axis sensor to generate a polar axis position output.

15. The diagnostic system according to claim 12, in, The diagnostic system is configured to determine when the mechanism is actuated regardless of whether current is flowing through the circuit interrupter.

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