DIAGNOSTIC DEVICE FOR A CIRCUIT, CORRESPONDING SWITCHING DEVICE AND DIAGNOSTIC PROCEDURES

Description

[0001] The present invention relates to a device for diagnosing a switching system. The present invention also relates to a switching device comprising such a diagnostic device and a diagnostic method implemented by such a diagnostic device.

[0002] To protect themselves from electrical faults and in particular overcurrents, many installations use switching devices (or "circuit breakers") configured to cut off the circulating current when the intensity of this current is too high compared to a reference value, for example set to prevent heating of electrical conductors carrying the current.

[0003] For this purpose, frequently used circuit breakers are of the so-called "magnetothermal" type. These circuit breakers use a switching system to open a switch and cut off the current, this switching system acting by two distinct and independent means.

[0004] A first part of the switching system controls the opening of the switch when a magnetic field generated by the current (all or part of which circulates, for example, in a coil) is greater than or equal to a threshold. For example, when the magnetic field is greater than or equal to the threshold, the force exerted by this magnetic field on a moving element exceeds another force, applied for example by a spring, and therefore causes the movement of this moving element to open the switch. These mechanisms then allow very rapid switching when the current is very high, and in particular in the event of very specific and intense overcurrents, typically due to a short circuit.

[0005] A second part controls the opening of the switch when a circuit breaker temperature (caused by an overload) is greater than or equal to another threshold. For example, a bimetallic strip in contact with the conductor in which the current flows (or a bimetallic strip itself crossed by the current) deforms, beyond a certain temperature, to cause the opening of the switch. These mechanisms are, by nature, less rapid than magnetic mechanisms, but allow tripping at lower current, to respond to less intense but longer-lasting overloads.

[0006] Furthermore, circuit breaker switching systems generally include a handle to allow an operator or user to manually open or close the switch.

[0007] Thus, in the event of a power outage caused by the circuit breaker, several different causes may be responsible, and these causes are of very different natures. It follows that it is advisable to determine in advance why the outage occurred before intervening to restart the installation and close the switch, particularly because the precautions to be taken are not the same depending on the case.

[0008] Document US 2005 / 103613 A1 describes a device for diagnosing the cause of a cut-off caused by a magnetothermal circuit breaker.

[0009] However, it is difficult to diagnose the reasons for such outages remotely. For example, when currents are very high, the sensors measuring the current intensity sometimes saturate, and it is therefore not possible to precisely determine the maximum value of the current and in particular whether it has reached the threshold that causes magnetic tripping of the switching system. In addition, the operation of the bimetallic strip is well established under optimal and controlled conditions, but can vary in reality compared to its nominal operation. It is then necessary to establish correspondence (or "derating") tables to link real conditions to nominal conditions, and thus take into account specific installation cases.

[0010] There is therefore a need for a device for diagnosing the switching of a magnetothermal circuit breaker, which is more reliable than the diagnostic devices of the state of the art.

[0011] There is therefore provided a diagnostic device according to claim 1.

[0012] According to advantageous but not mandatory embodiments, the diagnostic device is according to any one of claims 2 to 10.

[0013] There is also provided a switching device according to claim 11.

[0014] According to advantageous but not mandatory embodiments, the switching device is according to any one of claims 12 and 13.

[0015] There is also provided a diagnostic method according to claim 14.

[0016] Characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of non-limiting example and made with reference to the appended drawings, in which: There figure 1 is a schematic representation of a switching device including a diagnostic device, and The figure 2 is a flowchart of the steps of a diagnostic process implemented by the diagnostic device of the figure 1 .

[0017] A switching device 10 is shown in the figure 1 .

[0018] The switching device 10 comprises a switching module 15 and a diagnostic device 20.

[0019] The switching device 10 will be described below in the case where the switching device 10 comprises a single pole, but it will appear to those skilled in the art that the number of poles (i.e. input-output pairs that the switching device 10 is each able to connect or disconnect) is likely to vary.

[0020] The switching module 15 and the diagnostic device 20 are, for example, separate devices from each other and together form the switching device 10. In particular, the switching module 15 and the diagnostic device 20 are, as described below, each contained in a separate housing.

[0021] It should be noted that according to a possible variant, the switching module 15 and the diagnostic device 20 are contained in the same single housing, and the elements making up the switching module 15 are not, for example, separated by a wall from the elements making up the diagnostic device 20.

[0022] The switching module 15 is known per se.

[0023] The switching module 15 comprises a first housing 22, at least one input 25, at least one output 30, a switching member 35 and a triggering system 40.

[0024] The first housing 22 at least partially accommodates the or each input 25, the or each output 30, the switching member 35 and the triggering system 40.

[0025] The first housing 22 is configured to electrically isolate the interior of the first housing 22 from the exterior of the first housing 22.

[0026] The number of input(s) 25 and the number of output(s) 30 are each equal to the number of pole(s) of the switching device 10, here equal to one.

[0027] The input 25 is electrically conductive and configured to be connected to a first device external to the switching device 10. The input 25 is, in particular, configured to receive an electric current from this external device.

[0028] The input 25 comprises, for example, an input connection terminal for allowing the connection of an electrical conductor or an electrical connector to the input terminal for electrically connecting the first external device to the input 25.

[0029] The input 25 comprises one or a plurality of electrical conductors connected together.

[0030] The input 25 passes through, for example, the first housing 22 to allow its connection to the first external device.

[0031] Alternatively, the input 25 is accommodated entirely in the first housing 22 but a portion of the input 25 intended to be connected to the first external device is arranged opposite an opening in the first housing 22 so as to allow the introduction of an electrical conductor into the first housing 22.

[0032] The first external device can be of any nature, for example an electrical distribution network.

[0033] The output 30 is configured to receive the electric current from the input 25 via the switching member 35. The output 30 is, furthermore, configured to transmit this current to a second device external to the switching device 10 to which the output 30 is configured to be connected.

[0034] The output 30 comprises, for example, an output connection terminal intended to allow the connection of an electrical conductor or an electrical connector to the output terminal to electrically connect the second external device to the output 30.

[0035] The output 30 passes through, for example, the first housing 22 to allow its connection to the second external device. Alternatively, the output 30 is accommodated entirely in the first housing 22 but a portion of the output 30 intended to be connected to the second external device is arranged opposite an opening in the first housing 22 so as to allow the introduction of an electrical conductor into the first housing 22.

[0036] The second external device can be of any nature, for example a domestic electrical network, or even a device consuming electrical energy.

[0037] The switching member 35 is, in a manner known per se, configured to switch between a first position and a second position.

[0038] When the switching member 35 is in the first position, the switching member 35 electrically connects the input 25 and the output 30.

[0039] When the switching member 35 is in the second position, the switching member 35 electrically isolates the input 25 and the output 30.

[0040] The switching member 35 comprises in particular, in a manner known per se, an electrical conductor movable between a position in which the electrical conductor is simultaneously connected to the input 25 and to the output 30, and a position in which the electrical conductor is disconnected from at least one of the input 25 and the output 30.

[0041] The switching member 35 also comprises a mechanism for moving the movable conductor between its two positions.

[0042] The trigger system 40 is configured, in a manner known per se, to control a switching of the switching member 35 from the first position to the second position, and vice versa.

[0043] In particular, the triggering system 40 comprises a triggering mechanism 45, a manual control member 50, a first thermal triggering subsystem 55 and a second magnetic triggering subsystem 60.

[0044] Due to the presence of the two subsystems 55 and 60, the switching module 15 is often referred to as a “thermal-magnetic circuit breaker”, in particular when it forms a device separate from the diagnostic device 20. In the case where these two elements 15 and 20 form the same device contained in the same housing, it is then the switching device 10 which is called a “thermal-magnetic circuit breaker”, as a whole.

[0045] The trigger mechanism 45 is configured to act on the switching member to switch the switching member 35 between its two positions.

[0046] The manual control member 50 is configured to be actuated by an operator so as to control the switching, by the trigger mechanism 45, of the switching member 35 from the first position to the second position, or vice versa.

[0047] The manual control member 50 comprises, for example, a lever that can be rotated about an axis between two positions, each corresponding to a position of the switching member 35.

[0048] Alternatively, the manual control member 50 comprises at least one button configured to cause the switching member 35 to switch from one of its positions to the other when the operator presses the button. According to one embodiment, the manual control member 50 comprises two buttons, one causing a switch from the first to the second position and the other from the second to the first position following pressure from the operator.

[0049] It should be noted that many different types of manual control organs 50 can be considered.

[0050] The first subsystem 55 is configured to control a switching of the switching member 35 from the first position to the second position when a first criterion is verified.

[0051] The first criterion is the fact that a first temperature of the switching module 15 is greater than or equal to a temperature threshold.

[0052] For example, the first subsystem 55 comprises, in a manner known per se, a bimetallic strip which is for example part of an electrical circuit connecting the switching member 35 to the output 30 and which is configured to be crossed by the current flowing from the input 25 to the output 30 when the switching member 35 is in the first position (or which is in contact with a conductor crossed by this current). The bimetallic strip is configured to deform according to its temperature and to act on the trigger mechanism 45 so as to switch the switching member 35 to its second position when the temperature of the bimetallic strip is greater than or equal to the temperature threshold. The first temperature is then the temperature of the bimetallic strip.

[0053] The temperature threshold is chosen, in a manner known per se, as being such that, during normal operation of the switching device 10 under nominal conditions, the Joule effect causes the first temperature to increase up to the temperature threshold when the current intensity is equal to or greater than a first current threshold for a predetermined duration.

[0054] The predetermined duration depends, for example, on the operating conditions and the adjustment of the bimetallic strip.

[0055] The first current threshold is, for example, between 1.05 and 1.3 times a maximum acceptable current without tripping, at a reference temperature (or "rating") of the device 10, according to standard IEC60898-1. However, this first threshold is likely to vary.

[0056] It should be noted that other types of first subsystem controlling a switching when a first temperature reaches a temperature threshold are also conceivable, in particular systems not including a bimetallic strip.

[0057] The second subsystem 60 is configured to control a switching of the switching member 35 from the first position to the second position when a second criterion is verified.

[0058] The second criterion is that a magnetic field generated by the current flowing between input 25 and output 30 is greater than or equal to a field threshold.

[0059] For example, the switching module 15 comprises a coil in which the current (or a portion of the current if this coil is connected in parallel with another electrical conductor) flows. The magnetic field generated by the coil acts on a movable element of the second subsystem 60. When the magnetic field is greater than or equal to the field threshold, the force exerted on the movable element by the magnetic field causes it to move, and this movement acts on the trigger mechanism 45 to control the switching of the switching member 35 to its second position.

[0060] The field threshold is chosen such that the current generates a magnetic field equal to the field threshold when the current has an intensity value equal to a second current threshold.

[0061] The second current threshold is in particular strictly greater than the first current threshold. The second current threshold is, for example, between 3 times and 10 times the rating. Thus, the triggering system 40 controls the switching of the switching member 35 to its second position when either of the first and second criteria is verified, or when both criteria are verified.

[0062] The diagnostic device 20 is configured to detect a switching of the switching member 35, to perform a diagnosis of the switching and to transmit diagnostic data to a device 62 external to the switching device 10.

[0063] The device 62 is, for example, a computer or a server provided with a human-machine interface and capable of transmitting the received data to an operator, for example by displaying the data on a screen of the human-machine interface.

[0064] By "performing a switching diagnosis" is meant that the diagnostic device 20 assigns the detected switching to one of the following causes: a trigger caused by the first subsystem 55 due to the first criterion, i.e. because the first criterion is verified or has been verified; a trigger caused by the second subsystem 60 due to the second criterion, i.e. because the second criterion is verified or has been verified; and a manual trigger, caused by an activation of the manual control member 50 by an operator.

[0065] The diagnostic data includes, for example, an identifier of the cause of the switching, for example “1”, “2” or “3”, or any indication allowing the device 62 to identify, among the three possible causes, the cause of the detected switching.

[0066] The diagnostic data optionally includes additional information such as: a time instant of the switching, voltage or current values ​​measured at the instant when the switching was controlled by the triggering system 40. The diagnostic device 20 includes a second housing 64, a switching sensor 65, a temperature sensor 70, a current sensor 75 and a controller 80.

[0067] The second housing 64 at least partially accommodates the switching sensor 65, the temperature sensor 70, the current sensor 75 and the controller 80.

[0068] The second housing 64 is, for example, configured to hold the switching sensor 65, the temperature sensor 70, the current sensor 75 and the controller 80 in position relative to each other.

[0069] The second housing 64 is, for example, fixed to the first housing 22 by one or more hook(s), and possibly by one or more electrical conductors. Alternatively, the second housing 64 and the first housing 22 are both fixed to the same support capable of holding them in position relative to each other.

[0070] It should be noted that embodiments of the diagnostic device 20 without housing 64 are also conceivable. In this case, the switching sensor 65, the temperature sensor 70, the current sensor 75 and the controller 80 are accommodated in the housing 22, for example.

[0071] The switching sensor 65 is configured to measure information relating to a switching of the switching member 35 and to signal to the controller 80 that a switching of the switching member 35 has taken place.

[0072] The switching sensor 65 is, for example, mechanically connected to the switching member 35 and partially movable with it so as to actuate a module generating an electrical signal depending on the position of the switching member 35.

[0073] Alternatively, the switching sensor 65 is configured to estimate the position of the switching member 35 by assessing whether or not a current is flowing between the input 25 and the output 30.

[0074] Alternatively, the switching sensor 65 detects by an electrical contact the position of the manual control member 50, which is itself integral with the position of the switching member 35.

[0075] Generally, many types of switching sensor 65 are likely to be used.

[0076] The temperature sensor 70 is configured to measure values ​​of a second temperature of the switching device 10, for example using a thermocouple.

[0077] The second temperature is, for example, measured inside the second housing 64. In this case, the second temperature is a temperature of the diagnostic device 20.

[0078] Alternatively, the second temperature is a temperature of the switching module 15, for example of an electrical conductor of the switching module 15, in particular a temperature of the input 25 or of the output 30. In this case, the temperature sensor 70 comes into contact with at least a part of the switching module 15, in particular of this electrical conductor, passing through at least the second housing 64 and optionally through the first housing 22.

[0079] The second temperature is, in particular, a temperature whose variation is correlated with the variation of the first temperature. The temperature sensor 70 is, for this purpose, frequently positioned in the immediate vicinity of the bimetallic strip, for example at a distance of one centimeter or less.

[0080] The current sensor 75 is configured to measure values ​​of an intensity of the current passing through the switching module 15 from the input 25 to the output 30.

[0081] For example, the current sensor 75 is configured to measure current values ​​periodically over time. The frequency of the measurements is, for example, greater than or equal to 1 kilohertz (kHz), for example equal to 20 kHz.

[0082] The current sensor 75 comprises, for example, a sensor 85 configured to measure current values ​​in analog form and an analog / digital converter 90 configured to convert the measured values ​​into a digital signal and to transmit the digital signal to the controller 80. It should be noted that the controller 80 and the analog / digital converter 90 are sometimes a single element performing these two functions.

[0083] Optionally, the current sensor 75 performs frequency filtering of the measured values, for example band-pass filtering around the expected frequency of the current, before transmitting the measured values ​​to the controller 80.

[0084] A saturation value is defined for the current sensor 75.

[0085] The saturation value is a maximum intensity value, in absolute value, that the current sensor 75 is capable of measuring. For example, when the current has an intensity value greater than or equal, in absolute value, to the saturation value, the current sensor 75 generates a signal indicating that the intensity of the current is equal, in absolute value, to the saturation value.

[0086] In other words, the saturation value is such that the current sensor 75 cannot differentiate, in absolute value, two currents having intensities greater in absolute value than the saturation value.

[0087] The sensor 85 comprises, for example, a conductive torus surrounding a conductor of the switching module 15 (for example surrounding a conductor forming a portion of the input 25 or the output 30) and configured to generate an electric current as a function of a magnetic field generated by the current flowing in said conductor. Measuring the intensity of the electric current generated by the torus then makes it possible to estimate the value of the magnetic field and therefore the intensity of the current flowing in the conductor.

[0088] It should be noted that many types of current sensors 75 are likely to be used, for example shunt sensors or current transformers, known per se to those skilled in the art.

[0089] The controller 80 is configured to detect a switching of the switching member 35 from at least one piece of information transmitted by the switching sensor 65.

[0090] The controller 80 is further configured to receive the measured intensity and second temperature values ​​and to diagnose a detected switching from the received intensity and second temperature values.

[0091] The controller 80 comprises, for example, a processor 95 and a memory 100.

[0092] The memory 100 contains software instructions configured to implement a method of diagnosing a switching of the switching device 10 when executed on the processor 95.

[0093] The controller 80 is configured to communicate with the external device 62, for example via a wireless data link or via a wired network.

[0094] Alternatively, the controller 80 is formed by a dedicated integrated circuit (in English, “Application-Specific Integrated Circuit”), by a set of programmable logic components, or even by any set of electronic components.

[0095] The operation of the diagnostic device 20 will now be described with regard to the figure 2 , which represents a flowchart of the steps of the diagnostic process implemented by this device 20.

[0096] The diagnostic method comprises an initial step 200, a detection step 205, a first calculation step 210, a first estimation step 215, a second estimation step 220, a first comparison step 225, a first diagnosis step 230, a second calculation step 235, a determination step 240, a third calculation step 245, a second comparison step 250, a second diagnosis step 255 and a third diagnosis step 260.

[0097] At the start of the initial step 200, the switching member 35 is in the first position, and a current flows through the switching member 35 from the input 25 to the output 30.

[0098] Current is, for example, an alternating current with a nominal period. The nominal period is, for example, equal to 50 Hertz (Hz), but is likely to vary from one installation to another.

[0099] During the initial step 200, at least one second temperature value is measured by the temperature sensor 70 and transmitted to the controller 80, in particular to the second diagnostic module 110.

[0100] For example, values ​​of the second temperature are measured periodically by the temperature sensor 70, with a time period of, for example, between 100 milliseconds (ms) and 10 seconds, although these values ​​are likely to vary, in particular depending on the thermal capacity of the bimetallic strip. Furthermore, the current sensor 75 measures at least one value of the intensity of the current flowing between the input 25 and the output 30. For example, intensity values ​​are measured by the current sensor 75 periodically. Alternatively, the intensity values ​​are measured continuously by the current sensor 75, for example over a sliding time window.

[0101] The initial step 200 is implemented until a switching from the first position to the second position of the switching member 35 takes place. This is represented by an arrow 265 on the figure 2 .

[0102] It is assumed that a switching takes place during the initial step 200.

[0103] The switching causes the switching sensor 65 to emit at least one signal indicating to the controller 80 that a switching has taken place.

[0104] The controller 80 detects the switching following receipt of the signal emitted by the switching sensor 65.

[0105] The controller 80 implements the detection step 205 following the detection of the switching.

[0106] During the detection step 205, the controller 80 detects whether a saturation of the current sensor 75 has occurred during a first time range immediately preceding the switching.

[0107] For example, the first time range has a predetermined time duration and ends at the instant of switching.

[0108] According to one embodiment, the first time range is defined as the time range over which a predetermined number of current values ​​are measured, the most recent of the values ​​measured over this first range being the last non-zero value measured (since switching cuts off the current).

[0109] The first time range is, for example, a time range having a duration equal to a nominal half-period of the current and ending at the instant of switching. Alternatively, the first time range has a duration equal to a plurality of nominal half-periods, for example 5 half-periods.

[0110] Saturation is, for example, detected if the current sensor 75 transmits to the controller 80 a plurality of successive intensity values ​​having values ​​equal to each other and equal, in absolute value, to the saturation value. Alternatively, the saturation value is an estimated value slightly lower than the actual saturation threshold, and saturation is then detected if the current sensor 75 transmits to the controller 80 a plurality of successive intensity values ​​having values ​​greater than or equal, in absolute value, to the saturation value.

[0111] If saturation is detected, the first calculation step 210 is implemented. Otherwise, the first estimation step 215 is implemented.

[0112] During the first calculation step 210, the controller 80 calculates at least one value of a time derivative of the measured intensity.

[0113] For example, the controller 80 calculates a value of a time derivative of the intensity at a time at which the intensity is equal to zero during the first time range, including at a time at which the intensity is equal to zero and the intensity value increases over time.

[0114] Alternatively, the controller 80 calculates a value of the time derivative of the intensity corresponding to each instant at which an intensity value was measured during the first time range.

[0115] The first calculation step 210 is followed by the second estimation step 220.

[0116] During the second estimation step 220, an intensity value is estimated by the controller 80. The estimated value is, in particular, a maximum value of the current intensity during the first time range.

[0117] The estimated intensity value is estimated from at least one calculated time derivative value, in particular from the time derivative value at the time at which the intensity is equal to zero.

[0118] Alternatively, the estimated intensity value is estimated from the maximum derivative value (in absolute value) among the calculated derivative values.

[0119] The estimated intensity value is, for example, estimated by considering that the current intensity is a sinusoidal function of time, and by calculating the estimated intensity value from knowing the value of the derivative at the instant when the intensity is equal to zero.

[0120] The maximum derivative value is for example considered to be the value of the derivative at an instant when the current is equal to zero and increases over time, since these statements are true when the current is a sinusoidal function of time.

[0121] The second estimation step 220 is followed by the first comparison step 225.

[0122] During the first estimation step 215, a maximum value of the intensity is estimated by the controller.

[0123] The maximum current value is, for example, the highest value among the current values ​​measured during the first time range. Alternatively, the maximum current value is estimated by interpolation or extrapolation from the measured current values, considering that the current is a sinusoidal function of time.

[0124] The first estimation step 215 is followed by the first comparison step 225.

[0125] During the first comparison step 225, the intensity value estimated during step 215 or 220 is compared to the second current threshold.

[0126] If the estimated intensity value is greater than or equal to the second current threshold, the first diagnostic step 230 is implemented. Otherwise, the controller 80 determines that the switching was not caused because the second criterion was verified, and the second calculation step 235 is implemented.

[0127] In the first diagnostic step 230, the controller 80 diagnoses the switching as being a switching caused due to the second criterion. In other words, the controller 80 concludes that the switching was caused by the second trigger subsystem 60 because the magnetic field generated by the current was greater than or equal to the field threshold.

[0128] In the first diagnostic step 230, the controller 80 generates and transmits to the remote device 62 a diagnostic message indicating that the switching was caused by the second subsystem 60.

[0129] Alternatively, the diagnostic device 20 generates a signal intended for an operator indicating the cause of the switching, for example by displaying a message on a screen of the diagnostic device 20, or by displaying an indicator such as a colored mobile element visible from outside the diagnostic device 20 and indicating the cause of the switching.

[0130] During the second calculation step 235, the controller 80 calculates an average value of the second temperature.

[0131] The average value is, for example, an arithmetic mean of second temperature values, i.e., an average calculated by summing a plurality of acquired second temperature values ​​and dividing the sum by the number of summed values.

[0132] The average value is, for example, calculated from second temperature values ​​acquired successively during a second time range.

[0133] The second time range has, for example, a predetermined time duration and is defined as the first time range having this duration and ending at the instant of switching.

[0134] According to one embodiment, the second time range is defined as the time range during which a predetermined number of current values ​​are measured, the most recent of the values ​​measured during this second range being the last non-zero value measured (since switching cuts off the current).

[0135] The second time range has, for example, a duration between 0 and 1 second.

[0136] The second calculation step 235 is followed by the determination step 240.

[0137] During the determination step 240, the controller 80 determines a third current threshold based on the calculated average value of the second temperature.

[0138] It should be noted that as a variant, the third threshold is determined based on a single second temperature value, measured for example at the instant of switching.

[0139] The third current threshold is such that the Joule effect causes the first temperature to increase to the temperature threshold when the current intensity is equal to or greater than the third current threshold for a predetermined duration and when the second temperature is equal to the calculated average value of the second temperature.

[0140] In other words, the third current threshold is calculated to take into account that, under the actual operating conditions of the switching module 15, the switching module 15 is likely to be heated or cooled by external factors and that thus, the relationship between the current intensity and the first temperature is likely to be different from what was considered to set the temperature threshold.

[0141] For example, if the temperature threshold has been set such that the first subsystem 55 triggers a switching of the switching member 35 when the current intensity is equal to the first threshold for a predetermined duration and the switching module 15 is placed alone in the middle of a volume of air at 15°C of 3 cubic meters (these values ​​being examples likely to vary), the switching will take place for a lower intensity if the switching module 15 is heated beyond 15°C, for example by neighboring appliances or during the summer. Conversely, during the winter or in the event of a strong air current, the triggering will take place at a higher intensity.

[0142] The third current threshold is, for example, determined from the average value of the second temperature and from a table, stored in the memory 100 and containing, for a plurality of stored values ​​of the second temperature, respective values ​​of the third threshold.

[0143] Alternatively, the table contains, for each second temperature value stored in the table, a coefficient such that the third threshold is determined by multiplying the first threshold by the coefficient.

[0144] Each coefficient value is strictly greater than zero.

[0145] For example, for a stored second temperature value strictly greater than the expected second temperature value when the switching device 10 is placed alone in the middle of a 3 cubic meter volume of air at 15°C, the corresponding coefficient value is strictly less than one. For a stored second temperature value strictly less than the expected second temperature value when the switching device 10 is placed alone in the middle of a 3 cubic meter volume of air at 15°C, the corresponding coefficient value is strictly greater than one.

[0146] When the average value of the second temperature is strictly between two successive values ​​of the second temperature stored in the table, the third threshold is, for example, calculated either by interpolation from the two third threshold values ​​corresponding to said two successive values ​​of the second temperature stored, or by interpolation from the two coefficient values ​​corresponding to these successive values.

[0147] Alternatively, if the average value of the second temperature is strictly between two successive values ​​of the second temperature stored in the table, the third threshold determined is the third threshold corresponding to the value of the second temperature stored closest to the average value.

[0148] The table is, for example, a table determined experimentally by measuring an intensity value at which the first subsystem 55 triggers switching for each stored second temperature value.

[0149] A difference between successive second temperature values ​​stored in the table is, for example, between 1 degree Celsius (°C) and 10°C, for example equal to 5°C.

[0150] Alternatively, the third threshold is calculated from a function, stored in the memory 100, and for example determined experimentally, linking the value of the third threshold to the second measured temperature. The function is, for example, an affine function defined by two coefficients stored in the memory 100.

[0151] It should be noted that according to a possible variant, the third threshold is calculated from a single value of the second measured temperature and not from an average value.

[0152] Generally, it should be noted that the third threshold is likely to be calculated or determined in different ways depending on one or more second temperature values.

[0153] The third calculation step 245 is implemented immediately after the determination step 240.

[0154] In the third calculation step 245, an average intensity value is calculated.

[0155] The average intensity value is, for example, calculated over the second time range.

[0156] The average intensity value is, for example, calculated from a plurality of successive RMS (Root Means Square) values, for example by an arithmetic mean of the RMS values.

[0157] The number of successive RMS values ​​entering into the calculation of the average intensity value is, for example, between 0 and 10, for example equal to 5.

[0158] According to one embodiment, the controller 80 periodically calculates, during the initial step 200, RMS values ​​from, for example, N intensity values ​​measured successively by the current sensor 75 (N being an integer strictly greater than 1).

[0159] An RMS value is calculated, in a manner known per se, by calculating the square root of the mean of the squares of the measured values, for example the square root of a ratio between, in the numerator, a sum of squares of the N intensity values ​​and, in the denominator, the number N.

[0160] The number N is, for example, equal to the number of intensity samples acquired during a nominal period of the current. In this case, the number N is, in particular, between 303 and 444 when the nominal frequency of the current is between 45 Hz and 66 Hz and the sampling is carried out at 20 kHz.

[0161] The third calculation step 245 is followed by the second comparison step 250.

[0162] In the second comparison step, the controller 80 compares the calculated average intensity value to the third threshold.

[0163] If the average intensity value is greater than or equal to the third threshold, the second diagnostic step 255 is implemented. Otherwise, the third diagnostic step 260 is implemented.

[0164] In the second diagnostic step 255, the controller 80 diagnoses the switching as a switching caused due to the first criterion. In other words, the controller 80 concludes that the switching was caused by the first trigger subsystem 55 because the first temperature was greater than or equal to the temperature threshold.

[0165] In the second diagnostic step 255, the controller 80 generates and transmits to the remote device 62 a diagnostic message indicating that the switching was caused by the first subsystem 55.

[0166] During the third diagnostic step 260, the controller 80 diagnoses the switching as being a switching caused by an activation of the manual control member 50 by an operator.

[0167] In the third diagnostic step 260, the controller 80 generates and transmits to the remote device 62 a diagnostic message indicating that the switching was caused by the manual control member 50.

[0168] By virtue of the invention, the diagnostic device 20 effectively differentiates between triggers caused by the subsystems 55 and 60 or by the manual control member 50, even when the switching device 10 is placed in an environment likely to heat or cool it compared to the nominal conditions for which the temperature threshold was chosen.

[0169] In particular, it is avoided that the diagnostic device 20 attributes a trigger to an erroneous cause because the temperature of the switching device 10 is high or on the contrary low compared to the nominal conditions. Indeed, taking into account the second temperature makes it possible to take into account the fact that the diagnostic device 10 is placed in temperature conditions different from those for which the first trigger subsystem 60 was initially calibrated.

[0170] The information transmitted to an operator who has to intervene on the installation comprising the switching device 10 is therefore more precise, which makes the intervention more relevant, faster, and above all more secure (since certain actions, relevant for one triggering cause, may prove dangerous for other causes).

[0171] Calculating the third threshold based on one or more measured second temperature values ​​makes it possible to accurately take into account the influence of the temperature of the diagnostic device 10 on the operation of the subsystem 55.

[0172] Using a table containing third threshold values ​​based on measured second temperature values ​​allows the third threshold to be calculated simply and quickly without high computing power.

[0173] The use of an average value of the second temperature accurately reflects the influence of the second temperature on the operation of subsystem 55.

[0174] When the maximum current value is calculated from a derivative of the measured current values, the maximum value can be calculated accurately even when it exceeds the saturation value of the current sensor 75.

[0175] However, in the absence of saturation, considering the maximum value as being directly the highest value among the measured values ​​allows faster processing and is more accurate than using the derivative.

[0176] Using the maximum value of the derivative in calculating the maximum value of the intensity allows for greater accuracy than using other values ​​of the derivative.

[0177] Comparing the maximum current value with the second current threshold makes it possible to detect switching according to the second criterion quickly and easily.

[0178] A switching caused by the manual control member 50 is easily and simply detected when it is determined that the first and second criteria do not apply, rather than providing specific processing such as detecting the actuation of the member 50 using a specific sensor. The switching device 10 is particularly simplified since this specific sensor is not required.

[0179] When the second temperature is a temperature of the diagnostic device 20, the diagnostic device 20 is particularly easy to manufacture since it is not necessary to provide access to the switching module 15 (for example) for the temperature sensor 70. In addition, the temperature sensor 70 is likely to be arranged inside a possible housing 64 and therefore to be protected, in particular when the device 20 and the module 15 are two separate devices provided with separate housings.

[0180] When the second temperature is a temperature of the switching module 15, the diagnosis is more accurate, since this second temperature more accurately reflects the first temperature. Erroneous diagnoses when, for example, the switching module 15 is not heated or cooled in a similar manner to the diagnostic device 10 are then avoided.

[0181] It should be noted that, according to a possible variant, which is not part of the invention, a switching caused by the first criterion is likely to be diagnosed by directly comparing a second temperature value, for example the average second temperature value, with a corresponding temperature threshold. For example, if the second temperature is the first temperature (in particular if the temperature sensor 70 measures a temperature of the bimetallic strip or of another element of the first subsystem 55), it is diagnosed that the switching is a switching due to the first criterion if and only if the second temperature value is greater than or equal to the temperature threshold at which the first subsystem 55 triggers the switching.

[0182] It should be noted that, according to a variant which is not part of the invention, steps 235 to 255 are not implemented. In this case, the diagnostic device 20 is only configured to differentiate a trigger due to the second criterion from a manual trigger by the member 50.

Claims

1. A diagnostic device (20) for a switching device (10) having a switching module (15), the switching module (15) having an input (25), an output (30), a switching member (35) and a trigger system (40), characterised in that the switching member (35) being configured to switch between a first position in which the switching member (35) electrically connects the input (25) and the output (30) and a second position in which the switching member (35) electrically isolates the input (25) from the output (30), the trigger system (40) being suitable for controlling switching of the switching member (35) from the first position to the second position, the trigger system (40) being a magneto-thermal trigger system configured to control switching when one of a first criterion or a second criterion is verified, the first criterion being the fact that a first temperature of an element of the trigger system (40) is greater than or equal to a temperature threshold, the second criterion being the fact that a magnetic field is greater than or equal to a field threshold, the magnetic field being generated by an electric current flowing between the input and the output when the switching member (35) is in the first position, the diagnostic device (20) comprising a controller (80) configured to detect switching of the switching member (35) from the first position to the second position, the diagnostic device (20) comprising a temperature sensor (70) configured to estimate values of a second temperature of the switching device (10), and a current sensor (75) configured to measure values of a current intensity of the current, the diagnostic device (20) being characterised in that the controller (80) is configured to, following the detection of a switch, diagnose the switching as being a switching due to the first criterion when at least one current value is greater than or equal to a said third current threshold, the third current threshold being a function of at least one of the estimated second temperature value(s).

2. A diagnostic device according to claim 1, wherein the controller (80) comprises a memory (100) and is configured to determine the third current threshold from a table, stored in the memory (100), containing third current threshold values as a function of the second temperature, or from a function stored in the memory and relating third current threshold values to values of the second temperature.

3. A diagnostic device according to any one of claims 1 or 2, wherein the controller (80) is configured to estimate at least one current value from at least one value of a derivative of the current measured by the current sensor, and to diagnose the switching as switching due to the first criterion as a function of the at least one estimated current value.

4. A diagnostic device of claim 3, wherein the controller (80) is configured to: - detect saturation of the current sensor (75), estimating at least one current value from at least one value of a derivative of the measured current and diagnose the switching as a function of at least the estimated current value when saturation is detected, and to - diagnose switching directly as a function of at least one current value measured by the current sensor (75) in the absence of saturation.

5. A diagnostic device according to claim 3 or 4 in which the current is an alternating current having a time period, each estimated current value being estimated from a derivative of the current, the derivative being a maximum derivative of the current over a time period of the current, each current value being, in particular, estimated by considering that the current is a sinusoidal function of time.

6. A diagnostic device according to any one of claims 1 to 5, wherein at least one second temperature value is an average value of the second temperature over a time range prior to switching.

7. A diagnostic device according to any one of claims 1 to 6, further comprising a current sensor (75) configured to measure values of a current magnitude, wherein the controller (80) is further configured to compare at least one current value of the current to a second current threshold and to diagnose switching due to the second criterion when the current value is greater than or equal to the second current threshold.

8. A diagnostic device according to claim 7, wherein the triggering system (40) comprises a member (50) configured to control switching in accordance with an operator command, the controller (80) being configured to diagnose a switch as being an operator-controlled switch if the controller does not diagnose the switch as being a switch due to the first criterion or the second criterion.

9. A diagnostic device according to any one of claims 1 to 8, wherein the second temperature is a temperature of the diagnostic device (20).

10. A diagnostic device according to any one of claims 1 to 8, wherein the second temperature is a temperature of the switch module (15).

11. A switching device (10) comprising a switching module (15) comprising an input (25), an output (30), a switching member (35) and a tripping system (40), the switching member (35) being configured to switch between a first position in which the switching member (35) electrically connects the input (25) and the output (30) and a second position in which the switching member (35) electrically isolates the input (25) from the output (30), the triggering system (40) being suitable for controlling a switching of the switching member (35) from the first position to the second position, the triggering system (40) being a magneto-thermal triggering system configured to control the switching when one of a first criterion or a second criterion is verified, the first criterion being the fact that a first temperature of an element of the triggering system (40) is greater than or equal to a temperature threshold, the second criterion being the fact that a magnetic field is greater than or equal to a field threshold, the magnetic field being generated by an electric current flowing between the input and the output when the switching member (35) is in the first position, the switching device (10) comprising a diagnostic device (20) according to any one of claims 1 to 10.

12. A switching device according to claim 11, wherein the diagnostic device (20) comprises a first housing (64) containing the controller (80), the switching module (15) comprising a second housing (22) containing the switching member (35) and the triggering system (40), the first housing (64) being separate from the second housing (22) and being configured to be secured to the second housing (22).

13. A switching device as claimed in claim 11, comprising a single main housing containing the diagnostic device (20) and the switching module (15).

14. A method of diagnosing switching in a switching device (10) comprising a switching module (15) having an input (25), an output (30), a switching member (35) and a trigger system (40), characterised in that the switching member (35) being configured to switch between a first position in which the switching member (35) electrically connects the input (25) and the output (30) and a second position in which the switching member (35) electrically isolates the input (25) from the output (30), the trigger system (40) being suitable for controlling switching of the switching member (35) from the first position to the second position, the tripping system (40) being a magneto-thermal tripping system configured to control switching when one of a first criterion or a second criterion is verified, the first criterion being the fact that a first temperature of an element of the tripping system (40) is greater than or equal to a temperature threshold, the second criterion being the fact that a magnetic field is greater than or equal to a field threshold, the magnetic field being generated by an electric current flowing between the input and the output when the switching member (35) is in the first position, the method being implemented by a diagnostic device (20) comprising a controller (80), a current sensor (75) and a temperature sensor (70), the method comprising the steps of: - measurement (200), by the temperature sensor (70), of at least one value of a second temperature of the switching device, - detection, by the controller (80), of switching of the switching member (35) from the first position to the second position, and - diagnosis (255), by the controller (80), of the switching as being a switching due to the first criterion when at least one current value is greater than or equal to a said third current threshold, the third current threshold being a function of at least one of the estimated second temperature value(s).