Method for estimating the tripping current of a circuit breaker, system, assembly, and associated computer program

Abstract

Method for estimating the tripping current of a circuit breaker, associated system, assembly, and computer program. The present invention relates to a method for estimating the tripping current of a circuit breaker, the circuit breaker being configured to switch from an armed configuration to a tripped configuration, a tripping current, of an intensity equal to the tripping current, flowing in the circuit breaker when it switches to the tripped configuration, the switching of the circuit breaker to the tripped configuration generating a sound, representative of the tripping current, the method comprising at least the following steps: acquisition (102) of an output signal (So) emitted by a microphone, the output signal being representative of the sound generated by the circuit breaker when it switches to the tripped configuration; calculation (108) of a plurality of metrics from the output signal (So);and determination (110) of a trigger intensity class via an artificial intelligence model, the trigger intensity class being chosen from a plurality of predetermined trigger intensity classes. Figure for the abstract: Figure 3;

Description

Title of the invention: Method for estimating the tripping current of a circuit breaker, system, assembly, and associated computer program

[0001] The present invention relates to a method for estimating the tripping intensity of a circuit breaker, an associated system, assembly, and computer program.

[0002] In order to monitor the operation of a circuit breaker and to plan predictive maintenance, it is known to measure the current flowing through the circuit breaker at the moment the circuit breaker switches to the tripped configuration, that is, becomes electrically insulating. The current flowing through the circuit breaker at the moment the circuit breaker switches to the tripped configuration is called the tripping current, and has a value called the tripping current.

[0003] However, measuring the tripping intensity is costly and intrusive, since it requires adding an intensity sensor inside the circuit breaker, more precisely on one of the circuit breaker conductors, this sensor having to be able to withstand tripping intensities whose values ​​can be high.

[0004] The aim of the invention is then to propose a method and a detection system allowing the trigger intensity to be estimated in a simple, non-intrusive and low-cost manner.

[0005] To this end, the invention relates to a method for estimating the tripping current of a circuit breaker, the circuit breaker being suitable for connection between a source and a load, the circuit breaker being configured to switch from an armed configuration, in which the circuit breaker conducts a current flowing between the source and the load, to a tripped configuration, in which the circuit breaker electrically isolates the load from the source, a tripping current, of an intensity equal to the tripping current, flowing in the circuit breaker when it switches to the tripped configuration, the switching of the circuit breaker to the tripped configuration generating a sound, representative of the tripping current, the method comprising at least the following steps, implemented by an electronic control module: - acquisition of an output signal emitted by a microphone, the output signal being representative of the sound generated by the circuit breaker when it switches to the triggered configuration; - Calculating a plurality of metrics from the output signal; and - determination of a trip intensity class via an artificial intelligence model, previously trained by machine learning to provide, from the plurality of metrics, the trip intensity class associated with the tripping current, the trip intensity class being chosen from a plurality of predetermined trip intensity classes, each trip intensity class corresponding to a trip intensity range.

[0006] Thanks to the invention, the estimation of the current intensity is simplified. Indeed, using sound to determine the tripping current intensity does not require complex or intrusive measurements, for example, inside the circuit breaker or on the circuit breaker contacts. The method is therefore easy to implement and non-intrusive. Furthermore, the use of an artificial intelligence model simplifies the determination of the tripping current intensity compared to traditional signal analysis and processing methods, and thus reduces the complexity of the method.

[0007] According to other advantageous aspects of the invention, the method comprises one or more of the following features, taken individually or in all technically possible combinations:

[0008] - The method further includes a step of filtering the output signal.

[0009] - The process further includes a normalization step to normalize in amplitude the output signal.

[0010] - The calculation of the plurality of metrics includes the calculation of a plurality of cepstral coefficients on the Mel scale from the output signal.

[0011] - The plurality of tripping intensity classes is formed of five trip intensity classes, each trip intensity class corresponding to a trip intensity range distinct from other trip intensity classes.

[0012] - The artificial intelligence model is a random forest.

[0013] - The method further comprises a step of transmitting the intensity class of triggering determined to a transmission module.

[0014] - The method further includes a step of assigning an intensity class to maximum triggering occurs at the triggering current if the microphone saturates during sound acquisition.

[0015] The invention also relates to a system for estimating the tripping current of a circuit breaker, the circuit breaker being suitable for connection between a source and a load, the circuit breaker being configured to switch from an armed configuration, in which the circuit breaker conducts a current flowing between the source and the load, to a tripped configuration, in which the circuit breaker isolates electrically the load of the source, a tripping current of intensity the tripping intensity flowing in the circuit breaker when it switches to the tripped configuration, the switching of the circuit breaker to the tripped configuration generating a sound, representative of the tripping intensity, the system comprising: - a microphone, configured to acquire the sound generated by the circuit breaker when it switches to the triggered configuration and to emit an output signal, the output signal being representative of the sound; - an electronic control module, configured to receive the output signal, the electronic control module comprising: • a computing unit configured to calculate a plurality of metrics from the output signal; and • a determination unit, configured to determine a trip intensity class via an artificial intelligence model, previously trained by machine learning to provide, from the plurality of metrics, the trip intensity class associated with the tripping current, the trip intensity class being chosen from a plurality of predetermined trip intensity classes, each trip intensity class corresponding to a trip intensity range.

[0016] The invention also relates to an electrical assembly comprising: - a circuit breaker, suitable for connection between a source and a load, the circuit breaker being configured to switch from an armed configuration, in which the circuit breaker conducts a current flowing between the source and the load, to a tripped configuration, in which the circuit breaker electrically isolates the load from the source, when a tripping current of a certain intensity flows through the circuit breaker, the switching of the circuit breaker into the tripped configuration generating a sound representative of the tripping intensity, the circuit breaker comprising a casing; and - an estimation system, attached to the casing.

[0017] The invention also relates to a computer program comprising software instructions which, when executed by a microcontroller, implement an estimation method as defined above.

[0018] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which: - [Fig.1] [Fig.1] is a diagram of an electrical assembly according to an embodiment of the invention; - [Fig.2] [Fig.2] is a diagram of an electronic control module according to an embodiment of the invention; - [Fig.3] [Fig.3] is a logic diagram of an estimation process according to a method of implementing the invention; - [Fig.4] [Fig.4] is a graph of an output signal.

[0019] Figure 1 represents an electrical installation 1. The electrical installation 1 comprises a source 3 and a load 5, electrically connected to each other by a phase conductor 7 and a neutral conductor 8. The source 3 supplies electricity and is, for example, an electric generator, a transformer, or an electrical network, for example, a mains power grid. The load 5 is a device that consumes electricity, such as a household electrical appliance, industrial equipment such as an electric motor, or a server. An electric current, hereafter simply referred to as current, flows between the source 3 and the load 5 through the phase conductor 7 and returns to the source 3 through the neutral conductor 8.

[0020] The current is advantageously a low voltage current, that is to say, a nominal voltage of the current is less than 1500V. The current is an alternating current, or alternatively, a direct current.

[0021] The electrical installation 1 comprises an electrical assembly 10. The electrical assembly 10 includes a circuit breaker 11, connected between the source and the load. The circuit breaker 11 is, for example, a molded case circuit breaker, or MCCB. The circuit breaker 11 includes a housing 12, which is made of an electrically insulating material. The housing 12 contains most of the other components of the circuit breaker 11, including circuit breaker contacts, which are not shown.

[0022] The circuit breaker 11 is configured to switch between an armed configuration, in which the contacts are closed and in which it conducts the current flowing between the source 3 and the load 5, and a tripped configuration, in which the contacts are open and in which it electrically isolates the source 3 from the load 5. The circuit breaker 11 is configured to switch to the tripped configuration in the event of a short circuit or overload of the electrical installation 1, in order to prevent excessive current from flowing in the electrical installation 1. The circuit breaker 11 is also configured to switch to the tripped configuration following a user command, for example, manually switching it to the tripped configuration by operating a handle of the circuit breaker 11.When circuit breaker 11 switches to tripped configuration, the current flowing through circuit breaker 11 is called tripping current, which has an intensity equal to a tripping current Id.

[0023] The electrical assembly 10 further includes a system 20 for estimating the tripping current Id of the circuit breaker 11. The estimation system 20 is fixed to the housing 12, for example by being glued or screwed onto the housing 12. Advantageously, the estimation system 20 includes an enclosure 22 which is fixed onto the housing 12.

[0024] The estimation system includes a microphone 24, an electronic control module 26, connected to the microphone 24, and a transmission module 28, connected to the electronic control module 26, advantageously housed inside the enclosure 22.

[0025] The electronic control module 26 comprises a processing unit 32 connected to a determination unit 34, as shown in [Fig. 2]. Advantageously, the electronic control module 26 further comprises a filtering unit 36, connected to a normalization unit 38, which is connected to the processing unit 32. Advantageously, the electronic control module 26 further comprises a transmission unit 40, connected to the determination unit 34.

[0026] In the example of [Fig. 2], the electronic control module 26 is formed, for example, of a processor 50 and a memory 52 associated with the processor 50. In the example of [Fig. 2], the calculation unit 32 and the determination unit 34, as well as, optionally, the filtering unit 36, the normalization unit 38, and the transmission unit 40, are each implemented as software, or a software component, executable by the processor 50. The memory of the electronic control module 26 is thus capable of storing calculation software and determination software, as well as, optionally, filtering software, normalization software, and transmission software. The processor is then capable of executing each of the following software components: calculation software and determination software, as well as, optionally, filtering software, normalization software, and transmission software.

[0027] In an alternative not shown, the calculation unit 32 and the determination unit 34, as well as optionally the filtering unit 36, the normalization unit 38 and the transmission unit 40 are each implemented in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or an integrated circuit, such as an ASIC (Application Specified Integrated Circuit).

[0028] Alternatively, when the electronic control module 26 is implemented in the form of one or more software programs, i.e., in the form of a computer program, also called a computer program or computer program product, it is further capable of being stored on a medium, not shown, that is readable by a computer, or by a microcontroller. The readable medium is, for example, a medium suitable to store electronic instructions and to be coupled to a bus of a computer system. For example, the readable medium is an optical disc, a magneto-optical disc, a ROM, a RAM, any type of non-volatile memory (e.g. FLASH or NVRAM) or a magnetic card. On the readable medium is then stored a computer program comprising software instructions which, when executed by a microcontroller, implement a method for estimating the tripping current Id of the circuit breaker 11 described in detail below, and with reference to [Fig.3].

[0029] When the circuit breaker 11 switches to the tripped configuration, it generates a sound. By sound, we mean mechanical vibrations propagating through the air, and not through a solid medium, such as the housing 12. The sound is caused, for example, by the appearance of an electric arc between the contacts at the moment they open, then by the dissipation of this arc, as well as by the movement of the contacts of the circuit breaker 11. In the case of a user opening without current in the contacts of the circuit breaker 11, the sound is caused solely by the movement of the contacts of the circuit breaker 11. Thus, the sound is representative of the tripping current Id.

[0030] The microphone 24 acquires the sound generated by the circuit breaker 11 when it switches from the armed configuration to the tripped configuration and emits an output signal So. The output signal So, shown in [Fig.4], is representative of the sound generated by the circuit breaker 11, and therefore of the tripping intensity Id.

[0031] In practice, the microphone 24 continuously acquires the sound generated by the circuit breaker and continuously emits a physical quantity, for example, a voltage or voltage modulation, or a current whose amplitude is directly proportional to the sound acquired by the microphone 24. As long as the sound acquired by the microphone 24 corresponds to a pressure variation AP strictly below a pressure threshold, this physical quantity contains no information relating to the tripping intensity Id. The pressure threshold is, for example, equal to IPa. "Equal to a value" means equal to that value plus or minus 1% of that value.

[0032] When the sound acquired by the microphone 24 corresponds to a pressure variation AP greater than or equal to the pressure threshold, the physical quantity forms an output signal So, which is then representative of the sound generated by the circuit breaker 11, and therefore of the tripping current Id. The output signal So includes a tripping event D, which is associated with the sound corresponding to the pressure variation greater than or equal to the pressure threshold.

[0033] Advantageously, the output signal So has a duration less than or equal to 200ms, for example equal to 150ms, centered around the triggering event. Alternatively, the output signal So has a duration of 150ms, with the trigger event being 100ms from the start of the output signal So.

[0034] Advantageously, the output signal So is sampled at a frequency less than or equal to 30kHz, for example equal to 24KHz.

[0035] The method for estimating the tripping current Id of the circuit breaker 11, one embodiment of which is described below with reference to [Fig.3], implements an estimation of the tripping current Id from the sound caused by the tripping and captured by the microphone 24. The steps of the method described below are implemented by the electronic control module 26.

[0036] The electronic control module 26 acquires the output signal So during a step 102.

[0037] Advantageously, the electronic control module 26 performs a filtering step 104 on the output signal So. For example, the electronic control module 26 performs high-pass filtering, for example with a cutoff frequency of 30 Hz, and low-pass filtering, for example with a cutoff frequency of 100 Hz. The filtering step 104 is advantageously implemented by the filtering unit 36.

[0038] Advantageously, the electronic control module 26 performs an amplitude normalization step 106 of the output signal So. Advantageously, the step 106 is implemented by the normalization unit 38.

[0039] The electronic control module 26 calculates a plurality of metrics from the output signal So, advantageously filtered and normalized, in step 108. More precisely, step 108 is implemented by the calculation unit 32.

[0040] Advantageously, the plurality of metrics is a plurality of cepstral coefficients on the Mel scale, or MFCC, from the English "Mel Frequency Cepstral Coefficients". For example, the MFCCs are calculated over five sliding windows, with 13 MFCCs being calculated for each window, forming a total of 65 coefficients calculated from the output signal So.

[0041] Alternatively, the metric plurality includes an RMS value, from the English Root Mean Square, or quadratic mean of the output signal So, a magnitude of the output signal So, that is to say the maximum in absolute value of the output signal So, and an average frequency of the output signal So. The average frequency of the output signal So is related to the current flowing in the circuit breaker 11, with high frequencies being associated with a low current, for example less than 250 A, and low frequencies being associated with a high current, for example greater than 2500 A.

[0042] Advantageously, the electronic control module 26 determines whether the output signal So is saturated at step 109, for example by recognizing the saturation modes of the microphone 24 by analyzing the metrics of the So signal or by analyzing the MFCCs. More specifically, step 109 is implemented by determination unit 34.

[0043] If the output signal So is not saturated, the electronic control module 26 determines, in a step 110 advantageously implemented by the determination unit 34, a trigger intensity class associated with the trigger current, via an artificial intelligence model. The artificial intelligence model is, for example, a random forest, but alternatively, is a support vector machine (SVM), a k-nearest neighbors (k-NN) model, or a neural network. The artificial intelligence model is pre-trained by machine learning, as described in more detail later.

[0044] The artificial intelligence model takes as input a plurality of metrics and, based on these metrics, provides the trip intensity class associated with the tripping current. For example, the artificial intelligence model provides the majority intensity class, the trip intensity class associated with the tripping current being the class with the highest probability of belonging.

[0045] The trip intensity class is chosen from a plurality of trip intensity classes, also simply called classes. The trip intensity classes are predetermined, for example by the manufacturer of the system 20, and each trip intensity class corresponds to a trip intensity range. For example, there are five trip intensity classes, and the intensity range of each class is distinct from that of the other classes. For example:

[0046] - a first class corresponds to a zero triggering intensity Id,

[0047] - a second class corresponds to a trigger intensity Id between strictly between 0 and 250A,

[0048] - a third class corresponds to a higher or equal to 250A and strictly less than 2500A,

[0049] - a fourth class corresponds to a higher or equal to 2500A and strictly less than 5000A, and

[0050] - a fifth class corresponds to a higher or equal to 5000A.

[0051] The first and second classes correspond in particular to an opening following a user command, the third class corresponds in particular to a tripping of the circuit breaker 11 following an overload. The fourth and fifth classes correspond, for example, to short circuits.

[0052] Alternatively, the plurality of classes consists of more or fewer than five classes.

[0053] If, during step 109, the electronic control module 26, or advantageously, the determination unit 34, determines that the output signal So is saturated, then it directly assigns the tripping current a so-called maximum tripping current class during a step 112. The maximum tripping current class corresponds to the class with the highest current range. For example, in the case of the five classes described above, the maximum tripping current class is the fifth class, corresponding to a tripping current Id greater than 5000 A.

[0054] Advantageously, the electronic control module 26 transmits the trip intensity class to the transmitting module 28 in a step 114. Step 114 is advantageously implemented by the transmission unit 40. The transmitting module 28 is, for example, connected via a wired connection or wirelessly, for example via Wi-Fi or Bluetooth, to a terminal external to the estimation system 10 (not shown), and following the transmission of the trip intensity class by the electronic control module, transmits the trip intensity class, which is received by the terminal and displayed, for example, as a message on the terminal. For example, the transmitting module 28 is a Wi-Fi or Bluetooth device.A user or technician is thus informed of the tripping intensity Id when circuit breaker 11 trips, which allows them to advantageously assess the severity of the electrical fault that caused circuit breaker 11 to switch to the tripped configuration, to estimate the condition of the circuit breaker and / or to plan predictive maintenance operations on circuit breaker 11 or on installation 1 more generally.

[0055] The artificial intelligence model is trained by supervised machine learning. For example, a plurality of output signals corresponding to different tripping intensities are recorded in a database. The output signals are then advantageously filtered. Advantageously, in order to take into account a possible distortion of the sound generated by the circuit breaker 11, caused by temperature variations in the environment in which the circuit breaker 11 operates, random noise between -3dB and +3dB is added to each filtered output signal, to form a plurality of noisy output signals. The noisy output signal is then advantageously normalized in amplitude, and then metrics, for example, MFCCs, are calculated for each noisy output signal. The MFCCs of each noisy output signal form the training data for the artificial intelligence model.

[0056] Advantageously, in order to increase the quantity of training data and / or balance the data collected between each class, data augmentation methods are used, such as the synthetic oversampling technique of minority, also called the SMOTE method, from the English "Synthetic Minority Over-Sampling Technique". The model is then trained on the training data, and advantageously, validated, for example by a cross-validation method.

[0057] Advantageously, particularly in the case where the artificial intelligence model is a random forest, the model is trained with a bagging method.

[0058] The normalization step 106 allows the same estimation system 20 to be used, implementing the process described above, on different circuit breakers, for example on two-pole circuit breakers and on three-pole circuit breakers.

Claims

Demands

1. A method for estimating the tripping current (Id) of a circuit breaker (11), the circuit breaker (11) being suitable for connection between a source (3) and a load (5), the circuit breaker (11) being configured to switch from an armed configuration, in which the circuit breaker (11) conducts a current flowing between the source (3) and the load (5), to a tripped configuration, in which the circuit breaker (11) electrically isolates the load (3) from the source (5), a tripping current, of an intensity equal to the tripping current (Id), flowing in the circuit breaker (11) when it switches to the tripped configuration, the switching of the circuit breaker (11) to the tripped configuration generating a sound, representative of the tripping current (Id), the method comprising at least the following steps, implemented by an electronic control module (26): - acquisition (102) of an output signal (So) emitted by a microphone (24),the output signal (So) being representative of the sound generated by the circuit breaker (11) when it switches to the tripped configuration; - calculation (108) of a plurality of metrics from the output signal (So); and - determination (110) of a trip intensity class via an artificial intelligence model, previously trained by machine learning to provide, from the plurality of metrics, the trip intensity class associated with the tripping current, the trip intensity class being chosen from a plurality of predetermined trip intensity classes, each trip intensity class corresponding to a trip intensity range (Id).

2. Method according to claim 1, further comprising a filtering step (104) of the output signal (So).

3. A method according to any one of the preceding claims, further comprising a normalization step (106) for normalizing the output signal (So) in amplitude.

4. A method according to any one of the preceding claims, wherein the calculation (108) of the plurality of metrics includes the calculation of a plurality of cepstral coefficients on the Mel scale from the output signal (So).

5. A method according to any one of the preceding claims, wherein the plurality of trip intensity classes is formed of five trip intensity classes, each trip intensity class corresponding to a trip intensity range (Id) distinct from the other trip intensity classes.

6. A method according to any one of the preceding claims, wherein the artificial intelligence model is a random forest.

7. A method according to any one of the preceding claims, further comprising a step of transmitting (114) the determined trip intensity class to an emitting module (28).

8. A method according to any one of the preceding claims, further comprising a step (112) of assigning a so-called maximum trigger intensity class to the trigger current if the microphone (24) saturates during the acquisition of the CNN

9. □Ull. Estimating system (20) for the tripping current (Id) of a circuit breaker (11), the circuit breaker (11) being suitable for connection between a source (3) and a load (5), the circuit breaker (11) being configured to switch from an armed configuration, in which the circuit breaker (11) conducts a current flowing between the source (3) and the load (5), to a tripped configuration, in which the circuit breaker (11) electrically isolates the load (3) from the source (5), a tripping current of the tripping current (Id) flowing in the circuit breaker (11) when it switches to the tripped configuration, the switching of the circuit breaker (11) to the tripped configuration generating a sound, representative of the tripping current (Id), the system (20) comprising: - a microphone (24),configured to acquire the sound generated by the circuit breaker (11) when it switches to the tripped configuration and to emit an output signal (So), the output signal (So) being representative of the sound; - an electronic control module (26), configured to receive the output signal (So), the electronic control module (26) comprising: • a computing unit (32) configured to calculate a plurality of metrics from the output signal (So); and • a determination unit (34), configured to determine a trip intensity class via an artificial intelligence model, previously trained by machine learning to provide, from the plurality of metrics, the trip intensity class associated with the tripping current, the trip intensity class being chosen from a plurality of predetermined trip intensity classes, each trip intensity class corresponding to a trip intensity range (Id).

10. Electrical assembly (10) comprising: - a circuit breaker (11), suitable for connection between a source (3) and a load (5), the circuit breaker (11) being configured to switch from an armed configuration, in which the circuit breaker (11) conducts a current flowing between the source (3) and the load (5), to a tripped configuration, in which the circuit breaker (11) electrically isolates the load (3) from the source (5), when a tripping current of intensity Id flows through the circuit breaker (11), the switching of the circuit breaker (11) into the tripped configuration generating a sound representative of the tripping intensity Id, the circuit breaker (11) comprising a housing (12); and - an estimation system (20) according to claim 9, fixed to the housing (12).

11. A computer program comprising software instructions which, when executed by a microcontroller, implement an estimation method according to any one of claims 1 to 8.

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