Circuit breakers and methods for determining contact wear based on temperature

Abstract

This invention discloses a circuit breaker including a temperature detection system configured to detect the measured temperature of at least one of a line conductor, a load conductor, a moving contact, and a stationary contact during operation of the circuit breaker. The measured temperature represents the degree of wear of a set of separable contacts. In one embodiment, the temperature detection system includes a temperature sensor, which is an infrared sensor. In another embodiment, the temperature detection system includes a temperature sensor that is in physical contact with a conductive structure within the circuit breaker, and therefore additionally employs a voltage filter that filters line voltage from the signal from the temperature sensor. In yet another embodiment, the temperature detection system uses a temperature sensor in physical contact with a conductive structure, but uses a wireless transceiver to wirelessly transmit the measured temperature.

Description

Technical Field

[0001] The concepts disclosed and claimed in this invention relate generally to circuit breakers, and more specifically to circuit breakers with temperature sensors and related methods, the temperature sensors detecting a temperature representing the operating temperature of a set of active contacts, and from which the degree of wear of the set of contacts can be determined. Background Technology

[0002] Circuit breakers are known to be used in a variety of applications where it is desirable to protect at least a portion of a circuit from various predetermined conditions, such as, but not limited to, overcurrent conditions, undervoltage conditions, ground fault conditions, and other conditions. It should be understood that such circuit breakers typically include a set of separable contacts for each electrode, which are capable of moving from a closed position to an open position when it is necessary to disconnect the circuit (such as under one of the aforementioned predetermined conditions or other conditions). Such circuit breakers are typically supplemented with a tripping unit that, upon triggering, moves each set of such separable contacts from the closed position to the open position. While such circuit breakers are generally effective for their intended purpose, they are not without limitations.

[0003] Whenever a circuit breaker moves from the closed position to the open position, an electric arc temporarily forms between the stationary contact and the moving contact, which moves away from the stationary contact. It is desirable to identify this arc as soon as possible because it causes vaporization of the metal on the opposing surfaces forming the set of separable contacts. This vaporization of the contact material can be characterized as contact wear, and such wear is generally undesirable. As the opposing surfaces of the contacts wear, the quality of the electrical connection formed between the mating opposing surfaces of the contacts decreases, which is also undesirable. Therefore, improvement is desired. Summary of the Invention

[0004] This invention discloses an improved circuit breaker including a temperature detection system configured to detect the measured temperature of at least one of a line conductor, a load conductor, a moving contact, and a stationary contact during operation of the circuit breaker. The measured temperature represents the operating temperature of the set of separable contacts and indicates the degree of wear of the set of separable contacts. In one embodiment, the temperature detection system includes a temperature sensor, which is an infrared sensor and detects the measured temperature without physical contact with the conductive structure of the circuit breaker. In another embodiment, the temperature detection system includes a temperature sensor that is in physical contact with the conductive structure within the circuit breaker, and therefore additionally employs a voltage filter that filters the line voltage from the signal output by the temperature sensor to distinguish the temperature component of the signal from the line voltage. In yet another embodiment, the temperature detection system employs a temperature sensor in physical contact with the conductive structure of the circuit breaker, but uses a wireless transceiver to wirelessly transmit the signal representing the measured temperature to another wireless transceiver.

[0005] Therefore, one aspect of the concept disclosed and claimed in this invention is to provide an improved circuit breaker that includes a temperature detection system that detects the measured temperature of the conductive structure of the circuit breaker, wherein the measured temperature represents the operating temperature of a set of separable contacts of the circuit breaker, and the operating temperature represents the degree of wear of the set of separable contacts.

[0006] Another aspect of the concept disclosed and claimed in this invention is to provide an improved method for determining the wear degree of a set of separable contacts of such a circuit breaker: by detecting a measured temperature representing the operating temperature of the set of separable contacts, and using the measured temperature to determine the wear degree of the set of separable contacts.

[0007] Therefore, one aspect of the concept disclosed and claimed in this invention is to provide an improved circuit breaker, the general properties of which can be described as including: a housing; a first conductor located on the housing; a second conductor located on the housing; a set of separable contacts, which can generally be described as including a movable contact electrically connected to the first conductor and a fixed contact electrically connected to the second conductor; a trip unit connected to the movable contact and configured to move the set of separable contacts between a closed state and an open state; and a temperature detection system, which can generally be described as including a temperature sensor configured to detect the temperature of at least one of the first conductor, the second conductor, the movable contact, and the fixed contact.

[0008] Another aspect of the concept disclosed and claimed in this invention is to provide an improved method for determining the wear degree of a set of separable contacts of a circuit breaker, the set of separable contacts being movable between a closed state and an open state and including moving contacts and stationary contacts. The method can generally be described as including detecting a measured temperature representing the operating temperature of at least one of the moving contacts and stationary contacts, and using the measured temperature to determine the wear degree of the set of separable contacts.

[0009] Another aspect of the concept disclosed and claimed in this invention is to provide an improved circuit breaker, the general properties of which can be described as including: a housing; a first conductor located on the housing; a second conductor located on the housing; a set of separable contacts, which can generally be described as including a movable contact electrically connected to the first conductor and a fixed contact electrically connected to the second conductor; a trip unit connected to the movable contact and configured to move the set of separable contacts between a closed state and an open state; and a temperature detection system, which can generally be described as including a temperature sensor and a processor device, the temperature sensor being configured to detect the temperature of at least one of the first conductor, the second conductor, the movable contact, and the fixed contact, and the processor device being generally described as including a processor and a memory storing a plurality of routines, which, when executed on the processor, cause the circuit breaker to perform operations, which can generally be described as including determining that the temperature has exceeded a predetermined value, and generating an output in response to making the determination. Attached Figure Description

[0010] A further understanding of the concepts disclosed in the invention and protected by the claims can be obtained from the following description when read in conjunction with the accompanying drawings, wherein:

[0011] Figure 1 This is a perspective view of an improved circuit breaker according to a first embodiment of the concept disclosed and claimed according to the present invention, the improved circuit breaker having a temperature detection system also disclosed and claimed according to the concept of the present invention;

[0012] Figure 2 It is along Figure 1 A partial cross-sectional view taken from line 2-2;

[0013] Figure 3 yes Figure 1 A schematic diagram of the processor device of the temperature detection system for a circuit breaker;

[0014] Figure 4 This is a flowchart depicting certain aspects of an improved method based on the concept disclosed and claimed according to the present invention;

[0015] Figure 5 This is a schematic diagram of a circuit breaker according to a second embodiment of the concept disclosed and claimed according to the present invention; and

[0016] Figure 6 This is a schematic diagram of a circuit breaker according to a third embodiment of the concept disclosed and claimed in this invention.

[0017] Similar numbers refer to similar components throughout the instruction manual. Detailed Implementation

[0018] An improved circuit breaker 4 according to a first embodiment of the concept disclosed and claimed by the present invention... Figure 1 The general outline is shown in the middle, and part of its cross-section is in Figure 2 As shown in the diagram, the circuit breaker 4 comprises three electrodes, i.e., one electrode for each of the three electrical phases. However, it should be noted that only one of the three electrodes is described in detail herein, as the other two electrodes are arranged in a similar manner, function in a similar manner, and are mechanically connected together to operate simultaneously between the closed and open positions.

[0019] Circuit breaker 4 includes housing 8, in Figure 1 The casing is shown here with its cover removed to better reveal the internal parts. (See image.) Figure 2 As best shown, the circuit breaker 4 also includes a first conductor 12, a second conductor 16, and a set of separable contacts 20 electrically inserted between the first conductor 12 and the second conductor 16, all of which are located on the housing 8. The first conductor 12, the second conductor 16, and the set of separable contacts 20 together form a conductive structure that creates a conductive path in the closed position of the set of electrical contacts 20, the conductive path being able to connect to line conductors and load conductors to provide power to the protected portion of the circuit.

[0020] As in Figure 2 As can be seen, the set of separable contacts includes a fixed contact 24 electrically connected to the second conductor 16. The set of separable contacts 20 also includes a movable contact 28 electrically connected to the first conductor 12. The set of separable contacts 20 in... Figure 2 The set of separable contacts 20 is depicted as being in the open position. It should be understood that the set of separable contacts 20 is movable between the aforementioned open and closed positions, wherein the fixed contact 24 and the movable contact 28 are physically engaged with each other, thereby electrically connecting themselves together.

[0021] The circuit breaker 4 also includes a trip unit 32 located on the housing 8 and operable to trigger the movement of the set of separable contacts 20 between a closed position and an open position. In a known manner, the trip unit 32 is configured to move the set of separable contacts 20 from the closed position to the open position in response to any of a variety of predetermined conditions, such as, but not limited to, overcurrent conditions, undervoltage conditions, ground fault conditions, etc.

[0022] The circuit breaker 4 also advantageously includes a temperature detection system 36 located on the housing 8. Figure 1 The temperature detection system 36 includes a sensor device 40. Figure 2 ) and data device 42 ( Figure 3 ).like Figure 2 As best shown herein, sensor device 40 includes a temperature sensor 44 carried by a guide 48, which is receptacle within a receiver 52 formed in housing 8. In the illustrated exemplary embodiment, temperature sensor 44 is an infrared temperature sensor that can detect temperature without physical contact with the object whose temperature is being detected. Guide 48 is formed of an elastic material and includes a plurality of elastic protrusions 56 capable of engaging with the surface of receiver 52 to hold guide 48 and temperature sensor 44 in a specific position within receiver 52. As used herein, the expression “a plurality” and its variations shall be broadly interpreted to mean any non-zero quantity, including a quantity of “one”. Sensor device 40 also includes an arcuate plate 60 and a pair of screws 64 receptacle through holes in plate 60 to mount plate 60 to housing 8. The arcuate shape of plate 60 allows a compressive load to be applied to guide 48 to retain guide 48 and temperature sensor 44 within receiver 52 using compressive force. The sensor device 40 also includes a wiring harness 68 extending from the temperature sensor 44 and a connector 72 opposite to the temperature sensor 44 and electrically connected to the wiring harness 68. In the illustrated exemplary embodiment, the connector 72 is connected to the data device 42.

[0023] Data device 42 may include processor device 76, which includes processor 80 and memory 84. Processor 80 may be any of a variety of processors, such as, but not limited to, microprocessors. Memory 84 may be any of a variety of electronic storage devices, such as, but not limited to, RAM, ROM, EPROM, flash memory, etc., and may be used as a machine-readable storage medium in the form of an internal storage area of ​​a computer. Memory 84 stores a plurality of routines 88 that, when executed on processor 80, cause circuit breaker 4 to perform various operations, such as those described herein. Memory 84 also stores a plurality of data tables 92 containing data values ​​that can be retrieved by one of the routines 88. Data device 42 also includes input device 82 for providing input signals to processor 80. Data device 42 also includes output device 86 for receiving output signals from processor 80.

[0024] Temperature sensor 44 is advantageously configured to detect the temperature of the second conductor 16. Since the second conductor 16 is electrically connected to the fixed contact 24, during operation of the circuit breaker 4, i.e., when power is supplied to the electrical load, resistive heat generated between the fixed contact 24 and the movable contact 28 is conducted from the set of separable contacts 20 to both the first conductor 12 and the second conductor 16 and through them. Because heat within the first conductor 12 and the second conductor 16 may dissipate to the surrounding atmosphere and other places via convection, etc., temperature sensor 44 is advantageously placed relatively close to the physical connection point between the set of separable contacts 20 in order to most accurately reflect the actual operating temperature of the set of separable contacts 20. However, it is understood that regardless of the specific location of any of the aforementioned conductive structures to which temperature sensor 44 is configured to detect its temperature, datasheet 92 is configured such that the operating temperature of the set of separable contacts 20 corresponds to the measured temperature. Furthermore, the corresponding operating temperature of the set of separable contacts 20 can be retrieved from the data table 92 based on the measured temperature already measured by the temperature sensor 44. That is, the temperature sensor 44 detects the measured temperature of any part of the first conductor 12, the second conductor 16, the fixed contact 24, or the movable contact 28 configured to be detected, and provides a signal representing the measured temperature to the input device 82, which provides input to the processor 80, which retrieves the corresponding operating temperature of the set of separable contacts 20 from the data table 92.

[0025] Based on the operating temperature retrieved from data sheet 92 and the duration of that operating temperature at the set of separable contacts determined by optional routine 88, routine 88 triggers an output to be generated by output device 86. For example, routine 88 may determine that the operating temperature exceeds a predetermined temperature corresponding to a preset wear level of the set of separable contacts 20, and in response, routine 88 may trigger the generation of an output by output device 86, such as by providing an input to trip unit 32 indicating that the wear of the set of separable contacts 20 should be assessed. For example, the output may be an instruction to display such a message on the display unit of circuit breaker 4, or the same message may additionally or alternatively be transmitted to an enterprise data system so that the notification can be viewed at a higher organizational level. As a further example, the output may be an instruction to illuminate a light or trigger an audible alarm on circuit breaker 4 itself, which a technician may interpret as an indication that the wear of the set of separable contacts 20 needs to be assessed. Furthermore, it is possible that a first indication that the operating temperature exceeds a predetermined operating temperature will only trigger further operations in the routine to determine whether the operating temperature has remained above the predetermined operating temperature for a predetermined period of time. If it is determined that the excessively high operating temperature has existed for the predetermined period of time, this may result in the triggering of an output indicating that further evaluation of possible excessive wear of the set of separable contacts 20 is required. On the other hand, if it is determined at some future time that the operating temperature drops below the predetermined operating temperature, this may result in a reset of the wear evaluation routine 88. In this case, if it is determined at some future time that the operating temperature of the set of separable contacts 20 exceeds the predetermined temperature, this may again trigger routine 88 to wait for an additional period of time to determine whether the excessively high operating temperature has been maintained for the predetermined period of time, and if so, trigger an output.

[0026] Alternatively, the output may simply be in the form of a degree of wear, which has been determined to correspond to a detected measured temperature or a corresponding operating temperature, or both. For example, a predetermined operating temperature for the set of separable contacts may be defined as the point at which the set of separable contacts 20 should be replaced or at least the wear of the set of separable contacts should be assessed. Furthermore, such a definition of wear may include, in addition, the duration for which the set of separable contacts 20 remains at an operating temperature above the predetermined operating temperature. For example, the predetermined operating temperature and the optional duration at or above that temperature may be defined as 100% wear level for the set of separable contacts 20. Therefore, routine 88 may include additional instructions that convert the detected measured temperature and the corresponding retrieved operating temperature of the set of separable contacts 20 into a percentage of wear for the set of separable contacts 20, i.e., for example, 60% wear. The wear percentage may be provided as an output to trip unit 32 or mechanism data system. Furthermore, based on the operating temperature retrieved from data sheet 92, data device 42 can output a command to trip unit 32 to trigger the movement of the set of separable contacts 20 from the closed position to the open position, thereby tripping circuit breaker 4, such as in extreme cases where the wear of the set of separable contacts 20 is so great that tripping circuit breaker 4 is necessary. Many variations are conceivable.

[0027] Figure 4 A flowchart is depicted in an exemplary manner, illustrating certain aspects of an improved method according to the concepts disclosed and claimed in this invention. The process may begin, as at 96, in which a measured temperature representing the operating temperature of at least one of the active contact 28 and the stationary contact 24 of the set of separable contacts 20 is detected. Then, as at 98, the process may continue, in which the measured temperature is used to retrieve the corresponding operating temperature of the set of separable contacts 20 from a data table 92, and then the corresponding operating temperature is used to determine the degree of wear of the set of separable contacts. In this regard, it should be understood that the data table 92 may include not only a table in which the measured temperature corresponds to the operating temperature of the set of separable contacts 20, but also, additionally or alternatively, the measured temperature may correspond to the degree of wear of the set of separable contacts. Furthermore, data curves or the like may be used instead of tabular data tables without departing from the spirit of the concepts disclosed and claimed in this invention.

[0028] In the illustrated exemplary embodiment, the data device 42 is depicted as a system separate from and electrically connected to the trip unit 32 or electrically connected to the enterprise data system. However, it should be understood that the trip unit 32 can have various contents of the data device 42 residing thereon, so that the data device 42 does not need to be provided as a separate structure in the form of a circuit board or the like. In this case, the connectors 72 of the sensor devices 40 of the various electrodes of the circuit breaker 4 will be directly connected to the trip unit 32, and the trip unit 32 itself will generate outputs provided on the circuit breaker 4 itself or output to the enterprise data system, or both. Other variations will be apparent.

[0029] An improved circuit breaker 104 according to a second embodiment of the concept disclosed and claimed by the present invention... Figure 5 The circuit breaker 104 is generally shown in the diagram. It is similar to circuit breaker 4, except that circuit breaker 104 includes a temperature detection system 136 with a temperature sensor 144 in the form of an exemplary thermocouple, which is in physical contact with the second conductor 116. Specifically, circuit breaker 104 includes a housing 108 on which a first conductor 112, a second conductor 116, and a set of separable contacts 120 are located. The set of separable contacts 120 includes a fixed contact 124 and a movable contact 128. Trip unit 132 is operable to disconnect the movable contact 128 from the circuit breaker. Figure 5 The closed position indicated by the solid line is moved to... Figure 5 The break point is indicated by the dashed line.

[0030] The temperature detection system 136 includes a sensor device 140 comprising the aforementioned temperature sensor 144 in physical contact with the second conductor 116. Due to this physical contact, the temperature sensor 144 is energized under the line voltage experienced by the second conductor 116. Thus, the signal output from the wiring harness 168 connected to the temperature sensor 144 includes a component attributable to the line voltage and another component, which is a voltage signal from the temperature sensor 144 representing the measured voltage detected by the temperature sensor 144. Therefore, the wiring harness 168 is advantageously connected to a voltage filter 170, which removes the signal component corresponding to the line voltage from the second conductor 166 from the signal output from the temperature sensor 144. This advantageously produces an output signal from the voltage filter 170, which is input to the trip unit 132 and represents the measured temperature of the second conductor 116.

[0031] The temperature detection system 136 includes the same processor, input, and output devices as those in the data device 42, whether or not such structures are integrated onto the circuit board including the temperature sensor 144, or whether or not such structures are integrated into the trip unit 132. Therefore, the temperature detection system 136 advantageously allows the temperature sensor 144 to be physically connected to the second conductor 116 and to be energized at line voltage without inputting line voltage to the trip unit 132, since the voltage filter 170 is advantageously inserted between the temperature sensor 144 and the trip unit 132. Other variations will be apparent.

[0032] An improved circuit breaker 204 according to a third embodiment of the concept disclosed and claimed by the present invention... Figure 6 The circuit breaker 204 is generally shown in the diagram. Similar to circuit breaker 104, circuit breaker 204 includes a temperature detection system 236 with a temperature sensor 244 physically connected to a second conductor 216 of a conductive path, which includes the second conductor 216, a first conductor 212, and a set of separable contacts 220. The temperature detection system 236 includes a sensor device 240 having an exemplary thermocouple in physical contact with the second conductor 216 as the temperature sensor 244, and the temperature sensor 244 is thus energized under line voltage. However, the temperature sensor 244 includes a wiring harness 268 electrically connected to a first wireless transceiver 274. The first wireless transceiver 274 wirelessly communicates with a second wireless transceiver 278, which is electrically connected to a trip unit 232 that controls the operation of the set of separable contacts 220.

[0033] The first wireless transceiver 274 wirelessly transmits a data signal to the second wireless transceiver 278, representing the line voltage combined with a voltage signal from the temperature sensor 244. However, since the wireless signal represents the value of the voltage received through the harness 268 and not the actual voltage applied to the trip unit 232, the trip unit 232 includes instructions as part of a routine residing thereon that ignore or subtract the portion of the voltage value representing the line voltage received from the second wireless transceiver 278. In other words, a voltage filter 170 is employed in the circuit breaker 104 because the signal output from the harness 168 includes the actual line voltage plus a component representing the measured temperature of the second conductor 116. As a result, such an excessively high voltage could potentially damage the trip unit 132; therefore, the line voltage is filtered out of the signal by the voltage filter 170. Since the line voltage supplied from wiring harness 268 to the first wireless transceiver 274 is not actually transmitted from the first wireless transceiver 274 to the second wireless transceiver 278, but rather a signal indicating the magnitude of the voltage detected from wiring harness 268 is transmitted, the trip unit 232 includes instructions that enable it to ignore the signal component corresponding to the line voltage. As described above, the trip unit 232 may have all the structure and data processing capabilities of the data device 42 incorporated therein, or the temperature detection system 236 may simply include the data device as a separate component from the trip unit 232, depending on the specific application requirements.

[0034] It should be understood that any of a variety of temperature sensors may be used in addition to those explicitly described herein. For example, a resistance temperature diode (RTD) may be used, and this RTD will be in physical contact with one of the conductive structures of a current-carrying circuit that passes through one of the circuit breakers mentioned above. In this case, the RTD will typically be in physical contact with one of the conductive structures, but it may be connected via a pair of wireless transceivers, such as the wireless transceivers provided in circuit breaker 204. Other variations and combinations are readily apparent.

[0035] While specific embodiments of the concepts disclosed in this invention have been described in detail, those skilled in the art will understand that various modifications and substitutions to those details can be developed based on the overall teachings of this disclosure. Therefore, the specific arrangements disclosed are merely illustrative and do not limit the scope of the concepts disclosed in this invention, which is defined by the full scope of the appended claims and any and all their equivalents.

Claims

1. A circuit breaker, the circuit breaker comprising: case; A first conductor, which is located on the housing; A second conductor, which is located on the housing; A set of separable contacts, the set of separable contacts including a movable contact electrically connected to the first conductor and a fixed contact electrically connected to the second conductor; A trip unit, connected to the movable contact, and configured to move the set of separable contacts between a closed state and an open state; and A temperature detection system includes a temperature sensor configured to detect the measured temperature of at least one of a first conductor, a second conductor, a movable contact, and a fixed contact, and a processor device including a processor and a memory storing a plurality of routines. The processor retrieves the corresponding operating temperature from a specified data table based on the measured temperature, and uses the operating temperature to determine the wear degree of the set of separable contacts; and Wherein, when the routine is executed on the processor, the routine causes the circuit breaker to perform an operation, the operation including: Make a first determination that the operating temperature has exceeded a predetermined value for a predetermined time period; and in response to making the first determination, generate an output; Make a second determination that the operating temperature has dropped below the predetermined value, and in response to making the second determination, reset the routine.

2. The circuit breaker according to claim 1, wherein the temperature sensor is in physical contact with at least one of the first conductor, the second conductor, the movable contact, and the fixed contact.

3. The circuit breaker of claim 2, wherein the circuit breaker is configured to be connected to a line conductor having a line voltage, and wherein the temperature detection system further includes a voltage filter configured to filter the line voltage from the signal output by the temperature sensor.

4. The circuit breaker according to claim 2, wherein the temperature detection system further includes a wireless transmitter connected to the temperature sensor and a wireless receiver wirelessly communicating with the wireless transmitter.

5. The circuit breaker according to claim 1, wherein the temperature sensor is not in physical contact with at least one of the first conductor, the second conductor, the moving contact, and the fixed contact.

6. The circuit breaker of claim 1, wherein the further operation includes generating at least one of an alarm and a notification as the output, the at least one of the alarm and notification representing at least one of the operating temperature and wear level of the set of separable contacts.

7. A method for determining the wear degree of a set of separable contacts of a circuit breaker, the set of separable contacts being movable between a closed state and an open state and including a movable contact and a fixed contact, the circuit breaker including a first conductor and a second conductor, the movable contact being electrically connected to the first conductor, and the fixed contact being electrically connected to the second conductor, the method comprising: The temperature of at least one of the first conductor, the second conductor, the movable contact, and the fixed contact is used as the measured temperature. Based on the measured temperature, retrieve the corresponding operating temperature from the specified data table; as well as The degree of wear of the set of separable contacts is determined using the operating temperature. Execute the routine to cause the circuit breaker to perform an operation, the operation including: Make a first determination that the operating temperature has exceeded a predetermined value for a predetermined time period; and in response to making the first determination, generate an output; Make a second determination that the operating temperature has dropped below the predetermined value, and in response to making the second determination, reset the routine.

8. The method of claim 7, further comprising generating at least one of an alarm and a notification representing the operating temperature as the output.

9. The method of claim 7, further comprising placing the temperature sensor in physical contact with at least one of the first conductor, the second conductor, the active contact, and the fixed contact.

10. The method of claim 9, further comprising filtering line voltage from the signal output by the temperature sensor.

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