Method for protecting a contactor and associated contactor

Abstract

This contactor (2) comprises a main switch (10) connected between an upstream connection point (6) and a downstream connection point (8), and, in parallel, an assembly (16) comprising a secondary switch (20), connected in series with a unidirectional conductive component (18). A processing unit (30) is configured to receive switching commands, control a sequence of opening and / or closing of the main switch and the secondary switch, the secondary switch being closed during a time range for processing the switching command, the main switch being operated when the secondary switch is closed.The computing unit performs a voltage level monitoring at an intermediate point (28), and when the voltage level is above a value of a first predetermined voltage threshold, outside a time range for processing a switching command, detects a malfunction of the secondary switch, and commands a closure of the main switch.

Description

[0001] The present invention relates to a method of protecting a contactor intended to establish, in the closed position, or to interrupt, in the open position, a circulation of a main electric current between an electrical energy source and at least one electrical load, the electrical energy being supplied under an alternating electrical voltage.

[0002] The invention also relates to a contactor implementing such a protection method.

[0003] The invention relates to the field of electrical contactors, commonly used to establish or interrupt the flow of electric current between an electrical power source and one or more electrical loads. In other words, a contactor is used to energize electrical loads, such loads being any type of electrical device, for example, a motor, a heating appliance, or a lighting device.

[0004] Such contactors open and close on command, for example manually or remotely. Advantageously, the control is electrical.

[0005] The opening and closing operation uses electrical contacts including contact pads, which are likely to wear out physically after a certain number of operations.

[0006] Furthermore, it is preferable to design contactors with reduced dimensions, allowing them to occupy as little space as possible in a cabinet or electrical panel, while reducing wear and tear to increase their lifespan.

[0007] French patent FR 3 099 289 describes an improved electrical endurance contactor comprising two switches: a primary switch connected between an upstream connection point for the electrical power source and a downstream connection point for the electrical load(s); and a secondary switch connected in series with a unidirectional conductive component. The secondary switch and the secondary switch are connected in parallel with the primary switch. This patent describes a method for controlling the primary and secondary switches, ensuring that, under normal operating conditions, the primary switch is switched to the open or closed position when the secondary switch is closed. Consequently, the primary switch is switched without any electrical current, and therefore without any noticeable effect on the contacts of the primary switch.Similarly, the switching of the secondary switch is carried out without switching of electrical current, therefore without noticeable effect on the contacts of this switch, thanks to the unidirectional conductive component and a switching control during the blocked state of this component.

[0008] Thus, in nominal operation, such a contactor is more robust and has an increased lifespan.

[0009] To ensure a small overall footprint, and to obtain a contactor of reduced dimensions, it is advantageous to choose switches with different specifications, in particular a main switch which supports the main current, and a secondary switch which supports a lower current, given that the secondary switch is intended to support the main current for a very short period, for example a period less than half a period of the main current (i.e. less than 10 milliseconds for a current of 50 Hz).

[0010] However, for such a contactor, any electrical fault or malfunction may cause damage to one or the other of the switches, and more particularly to the secondary switch, which can then no longer perform the originally intended function.

[0011] There is therefore a need to improve the protection of such a contactor against malfunctions, while retaining the advantages of robustness and compactness.

[0012] To this end, the invention relates to a method for protecting a contactor intended to establish, in the closed position, or to interrupt, in the open position, a circulation of a main electric current between an electrical energy source and at least one electrical load, the electrical energy being supplied under an alternating electrical voltage, the contactor having an upstream connection point intended for a connection to the electrical energy source and a downstream connection point intended for a connection of said at least one electrical load, the contactor comprising a main switch connected between the upstream connection point and the downstream connection point, and an assembly comprising a secondary switch, connected in series with a unidirectional conductive component, said assembly being connected between the upstream connection point and the downstream connection point in parallel with the main switch,the contactor further comprising a processing unit configured to receive switching commands from the contactor and to control a sequence of opening and / or closing of the main switch and the secondary switch, depending on the switching command received and the polarity direction of the alternating electrical voltage, the secondary switch being closed during a time range for processing the switching command, the main switch being controlled to open or close when the secondary switch is closed.

[0013] This process involves implementation by the calculation unit in stages of: monitoring a voltage level at an intermediate point located between the secondary switch and the unidirectional conductive component, when said voltage level is greater than a value of a first predetermined voltage threshold, outside a time range for processing a switching command, detection of a malfunction of the secondary switch, and command to close the main switch.

[0014] Advantageously, voltage level monitoring makes it possible to detect an abnormal closure of the secondary switch, and to take immediate measures to prevent further damage to the contactor.

[0015] The method of protecting a contactor according to the invention may have one or more of the characteristics below, taken independently or according to all acceptable combinations.

[0016] Voltage level monitoring is performed continuously or at a chosen time frequency.

[0017] The process also includes: Following a switching command reception, a comparison of the voltage level at the intermediate point to a value of a second voltage threshold, and if the voltage level at the intermediate point is less than the value of the second voltage threshold during the switching command processing time range, detection of a malfunction of the secondary switch; following a switching command reception, the steps of: determining a voltage difference between an input voltage, as measured at the upstream connection point, and an output voltage, as measured at the downstream connection point, comparing said voltage difference with a predetermined voltage difference threshold, and, if said voltage difference is greater than the predetermined voltage difference threshold, detection of a malfunction of the secondary switch;Following the detection of a secondary switch malfunction, a contactor blocking command is issued; following the detection of a secondary switch malfunction, a contactor malfunction status indicator is activated; following the receipt of a switching command in the open position, the voltage level at the downstream connection point is monitored, and if said voltage level at the downstream connection point exceeds a third voltage threshold value during the command processing time range, a predetermined number N of opening attempts are initiated, and a contactor fault status is indicated. If, after N opening attempts, the voltage level at the downstream connection point remains above the third voltage threshold value, a contactor blocking command is issued and a contactor malfunction status indicator is activated.Following a switching command received in the closed position, monitoring of a voltage level at the downstream connection point, and if said voltage level at the downstream connection point is less than a value of a fourth voltage threshold during the command processing time range, implementation of a predetermined number M of closing attempts, and an indication of contactor error status; if after M closing attempts, the voltage level at the downstream connection point remains less than the value of the fourth voltage threshold, a contactor blocking command is issued and an indication of a contactor malfunction status is implemented.

[0018] The invention also relates to a contactor intended to establish, in the closed position, or to interrupt, in the open position, a flow of a main electric current between an electrical energy source and at least one electrical load, the electrical energy being supplied under an alternating electrical voltage, the contactor having an upstream connection point intended for a connection to the electrical energy source and a downstream connection point intended for a connection of said at least one electrical load, the contactor comprising a main switch connected between the upstream connection point and the downstream connection point, and an assembly comprising a secondary switch, connected in series with a unidirectional conductive component, said assembly being connected between the upstream connection point and the downstream connection point in parallel with the main switch,the contactor further comprising a processing unit configured to receive switching commands from the contactor and to control a sequence of opening and / or closing of the main switch and the secondary switch, depending on the switching command received and the polarity direction of the alternating electrical voltage, the secondary switch being closed during a time range for processing the switching command, the main switch being controlled to open or close when the secondary switch is closed, the processing unit being configured to implement a protection method as briefly described above.

[0019] This contactor also includes a first voltage measurement module at the upstream connection point, a second voltage measurement module at the downstream connection point and a third voltage measurement module at the intermediate point, each of said modules being connected to the calculation unit.

[0020] In one embodiment, the main switch is a bistable electromechanical relay and the secondary switch is a monostable electromechanical relay.

[0021] Other features and advantages of the invention will become apparent from the description given below, by way of example and not limitation, with reference to the attached figures, including: there figure 1 is a block diagram of a contactor according to one embodiment; the figure 2 is a diagram illustrating a sequence of switch states following a contactor closing command in nominal operation; the figure 3 is a diagram illustrating a sequence of switch states following a contactor opening command in nominal operation; the figure 4 is a synoptic diagram of the main steps in a contactor protection process for detecting a malfunction of the secondary switch; the figure 5 represents another embodiment of certain steps in a contactor protection process for detecting a malfunction of the secondary switch; the figure 6 is a synoptic diagram of the main steps of a contactor protection process for the detection of a malfunction of the main switch.

[0022] There figure 1 illustrates a contactor 2 intended to establish, in the closed position, or to interrupt, in the open position, a circulation of a main electric current I between an electrical energy source 4 and at least one electrical load 5, the electrical energy being supplied under an alternating electrical voltage.

[0023] In the figure 1 , only one electric charge 5 has been represented, it being understood that the electric charge 5 may consist of one or more electrical devices such as motors, heating resistors, lighting devices, or any other device requiring a connection to an electrical power source.

[0024] The electrical power source 4 is for example an electrical power distribution network or an electrical power generator, and provides a predefined alternating voltage Ug, for example 240 Volts and 50 Hertz.

[0025] The contactor 2 includes an upstream connection point 6 and a downstream connection point 8, the upstream connection point 6 being intended to be connected to the electrical power source 4 and the downstream connection point 8 being intended to be connected to the electrical load 5.

[0026] The electrical energy source 4 is connected on one side to the upstream connection point 6 and on the other side to the electrical load 5. The connection between the electrical energy source 4 and the electrical load 5 is for example a phase line or a neutral line.

[0027] To clarify the description, the alternating electrical voltage Ug is referenced with respect to a potential reference point 12 which may or may not be integrated into the contactor.

[0028] The contactor 2 also includes a main switch 10 connected between the upstream connection point 6 and the downstream connection point 8.

[0029] The contactor 2 also includes an assembly 16 connected in parallel with the main switch 10 between the upstream connection point 6 and the downstream connection point 8, the assembly 16 including a secondary switch 20 connected in series with a unidirectional conductive component 18.

[0030] In the implementation of the figure 1 The unidirectional conductive component 18 is a diode, whose anode is disposed on the side of the electric current source 4 and the cathode on the side of the electric load 5. Alternatively, the unidirectional conductive component 18 can be a thyristor.

[0031] The contactor 2 further comprises a first voltage measurement module 22 at the upstream connection point 6, a second voltage measurement module 24 at the downstream connection point 8 and a third voltage measurement module 26 at an intermediate point 28, located between the secondary switch 20 and the unidirectional conductor component 18, and more precisely downstream of the secondary switch 20 and upstream of the unidirectional conductor 18.

[0032] The contactor 2 also includes a computing unit 30, implemented for example in the form of one or more microprocessors or microcontrollers, or in the form of logic circuits, or discrete components, for example in an ASIC (from the English Application Specific Integrated Circuit ) .

[0033] The first, second and third voltage measurement modules provide the voltage measurements to the computing unit 30.

[0034] The computing unit 30 is configured to receive switching commands from the contactor, from a remote device 35, via a wired or wireless communication link. For example, the communication link is wireless and the remote device 35 is a remote control.

[0035] In one embodiment, the computing unit 30 is programmed, remotely via an application or locally via a human-machine interface, to implement switching commands, for example triggered by the internal clock of the computing unit 30.

[0036] In one embodiment, the first voltage measurement module 22, the second voltage measurement module 24 and the third voltage measurement module 26 are each implemented by a circuit comprising a voltage divider bridge, with an additional calculation to obtain the measurement of a corresponding voltage level being performed by the calculation unit 30.

[0037] In nominal operation, upon receiving a switching command from contactor 2, the processing unit 30 is configured to control a sequence of opening and / or closing of the secondary switch 20 and the main switch 10, depending on the received switching command and the polarity of the alternating electrical voltage Ug. This involves performing opening and closing maneuvers of each of the switches 10 and 20 with a low electrical current at their terminals to protect them from mechanical wear. This nominal operation is detailed below, particularly with reference to... figures 2 And 3 .

[0038] In one embodiment, the main switch 10 is an electromechanical relay having at least one moving contact, controlled by a coil, to establish contact with a fixed contact. Such an electromechanical relay is a compact and inexpensive component, and the mechanical resistance between the closed contacts is low.

[0039] Preferably, the secondary switch 20 is also an electromechanical relay.

[0040] In a preferred embodiment, the main switch 10 is a bistable electromechanical relay and the secondary switch 20 is a monostable electromechanical relay, which has a smaller footprint than a bistable electromechanical relay. Thus, the overall volume of the contactor 2 is smaller.

[0041] Furthermore, preferably, the main switch 10 is an electromechanical relay capable of switching a rated current less than or equal to, for example, 20 or 25 Amperes at a voltage of 240 Volts. The secondary switch 20 can advantageously be smaller than the main switch 10, for example, five to ten times smaller in volume / size, because it is intended to withstand the main electrical current I for a very short duration, for example, less than half a period of the main electrical current I (i.e., a duration of less than 10 ms for a current at 50 Hz), whereas the main switch 10 must withstand the main electrical current I for an indefinite duration, depending on the time between a closing and opening command of the switch.

[0042] There figure 2 Figure 5 illustrates the sinusoidal alternating voltage signal Ug as a function of time, along with the polarity of the alternating voltage, indicated by the symbols "+" and "-". The sinusoidal alternating voltage signal has a period of duration T. During half a period T1 (respectively T3), the alternating voltage Ug is positive, and the polarity is positive. During the following half a period T2 (respectively T4), the alternating voltage Ug is negative, and the polarity is negative. The sum of the half-periods T1 and T2 is equal to the period T.

[0043] There figure 2 illustrates the open or closed states of the main switch 10 and the secondary switch 20 over the half periods T1, T2, T3, T4, forming a sequence of states following a switching command to close of the contactor 2, i.e. a command to switch from an open state to a closed state of the contactor 2.

[0044] In order to better preserve the contacts of switches 10, 20 from electrical wear (wear of the contact pads), it is provided that the secondary switch 20 is operated when the unidirectional conductive component 18 is in a blocked state, that is to say when the direction of polarity of the alternating electrical voltage Ug imposes a reverse voltage across the terminals of the unidirectional conductive component 18.

[0045] During half-period T1, the polarity of the alternating electrical voltage Ug is positive, and both switches 10 and 20 are open. During the following half-period T2, the polarity of the alternating electrical voltage Ug is negative, the unidirectional conductive component 18 is in a blocked state, and the secondary switch 20 is closed. Because the unidirectional conductive component 18 is blocked, closing the secondary switch 20 has no noticeable effect on its contacts. This secondary switch 20 remains in the closed position for a period known as the switching control processing time range TC.Following the closure of the secondary switch 20, during half-period T3, when the polarity of the alternating electrical voltage Ug is positive, the main electrical current flows through the secondary switch 20 and the unidirectional conductive component 18, which is then conducting, and the voltage across the main switch 10 is low. The processing unit 30 then commands the main switch 10 to close, and the main electrical current I then flows through the main switch 10. During the following half-period T4, the polarity of the alternating electrical voltage Ug is negative, the unidirectional conductive component 18 is in a blocked state, and the secondary switch 20 is then open without damage to its contacts, the electrical current being zero because it is blocked by the component 18. The contactor 2 is then in the closed position, in accordance with the command received.

[0046] There figure 2 also schematically illustrates in a second graph 52 the open / closed state of the secondary switch 20 as a function of time, and in a third graph 54 the open / closed state of the main switch 10 as a function of time, in the case of processing a closing command of the contactor.

[0047] Similarly, the figure 3 illustrates the open or closed states of the main switch 10 and the secondary switch 20, in nominal operation, over half periods T5, T6, T7, T8, forming a sequence of states following a switching command to open of the contactor 2, i.e. a command to change from a closed state to an open state of the contactor 2. Initially, the main switch 10 is closed and the secondary switch 20 is open.

[0048] There figure 3 Graph 56 illustrates the sinusoidal alternating current voltage signal Ug as a function of time, along with the polarity of the alternating current voltage, indicated by the symbols "+" and "-". The sinusoidal alternating current voltage signal has a period of duration T. During half a period T5 (respectively T7), the alternating current voltage Ug is positive, and the polarity is positive. During the following half a period T6 (respectively T8), the alternating current voltage Ug is negative, and the polarity is negative. Graph 58 schematically illustrates the open / closed state of the secondary switch as a function of time, and Graph 60 the open / closed state of the main switch as a function of time, in the case of processing a contactor opening command under normal operating conditions.

[0049] During half-period T5, the polarity of the alternating electrical voltage Ug is positive, the main switch 10 is closed, and the secondary switch 20 is open. During the following half-period T6, the polarity of the alternating electrical voltage Ug is negative, and the unidirectional conductive component 18 is in a blocked state. Due to the blocked state of the unidirectional conductive component 18, closing the secondary switch 20 has no noticeable effect on its contacts. This secondary switch 20 remains in the closed position for a specific time period during the processing of the switching command TC.Following the closure of the secondary switch 20, during half-period T7, when the polarity of the alternating current voltage Ug is positive, the processing unit 30 commands the opening of the main switch 10. The main current I then flows through the secondary switch 20 and the unidirectional conductor. During the following half-period T8, the polarity of the alternating current voltage Ug is negative, the unidirectional conductor 18 is in a blocked state, and the secondary switch 20 is therefore open. The contactor 2 is then in the open position, in accordance with the command received.

[0050] As is clear from the description of the figures 2 And 3In nominal operation, the main switch 10 is controlled to open or close when the secondary switch 20 is closed, during the switching control processing time range and in the positive alternation of the voltage.

[0051] The purpose of the contactor protection process is to detect and protect the contactor in the event of a malfunction of one of the switches, i.e. when one of the switches does not behave as in nominal operation.

[0052] In particular, the protection process detects malfunctions of the secondary switch, which are of two types: either a first type malfunction in which the secondary switch is abnormally closed, or a second type malfunction in which the secondary switch is abnormally open.

[0053] Indeed, the secondary switch 20 may remain abnormally closed due to a mechanical or electrical fault, for example, following an electrical current overload, or because one of its contacts has become resistive due to a shock wave, for example. In this case, particularly when the secondary switch 20 is not designed to withstand the main electrical current over a prolonged period, the secondary switch 20 may be damaged.

[0054] The secondary switch 20 may remain abnormally open, for example, if it is damaged due to a mechanical or electrical fault. In this case, the secondary switch 20 cannot perform its protective function (zero-current / voltage switching) against wear of the main switch contacts during normal operation.

[0055] Similarly, the protection process detects malfunctions of the main switch, which are of two types: either a third type malfunction in which the main switch is abnormally closed, or a fourth type malfunction in which the main switch is abnormally open.

[0056] There figure 4 is a synoptic diagram of the main steps in a process for protecting a contactor of the type described with reference to the figure 1 , implemented by the contactor's calculation unit 30. These steps involve detecting a malfunction of the secondary switch and activating the protection accordingly.

[0057] The process includes monitoring 80 of a voltage level at the intermediate point 28 (i.e. voltage downstream of the secondary switch 20), this voltage level being supplied by the third voltage measurement module 26.

[0058] The voltage level monitoring 80 at the intermediate point 28 is performed continuously or at a given time frequency, asynchronously with any contactor switching command processing 100, i.e., independently of any ongoing processing 100 of a received switching command. For example, the voltage level monitoring 80 at the intermediate point 28 is performed at a time frequency of approximately 10 to 30 ms. A filtering (or time delay) of 30 to 50 ms may be applied to prevent the detection of a false fault (such as a temporary surge).

[0059] Next, it is checked whether the voltage level V int at the intermediate point 28 is greater than a value of a first predetermined voltage threshold V th-F1, outside a time range for processing a switching command, therefore outside a closure in an opening and closing sequence following a command reception.

[0060] In the method of implementation of the figure 4 This verification is performed in two stages. First, in step 82, it is checked whether the voltage level Vint at intermediate point 28 is greater than the value of the first predetermined voltage threshold Vth-F1. If Vint > Vth-F1, it is also checked (step 84) whether a switching command processing range is in progress. The value of the first predetermined voltage threshold Vth-F1 is, for example, between 20V and 50V.

[0061] Exceeding the first predetermined voltage threshold V th-F1 indicates the presence of voltage across the terminals of the secondary switch 20.

[0062] If voltage is present across the terminals of the secondary switch 20, outside the processing range of a switching command, it is deduced that the secondary switch is abnormally closed, it is in a state of first type malfunction.

[0063] Step 84 is then followed by step 86, which commands the main switch to close, and then by step 88, which locks the contactor. Locking the contactor results in the refusal to process any switching command to the contactor.

[0064] Furthermore, preferably, the method includes the implementation of a malfunction indicator, and therefore an indicator of the contactor's blocked state. In this case, the blocked state is a blocked state in the closed position. For example, the indicator is a light located on a visible face of the housing containing the contactor, preferably the front face visible to the user, and the malfunction indicator, here a type 1 malfunction, is a chosen color of the light, for example red, and / or a flashing state of the light. Of course, other variants of the contactor malfunction indicator are conceivable.

[0065] The process also includes, in the switching command processing 100, following a switching command reception 102, in addition to implementing the opening and / or closing sequence of the main switch and the secondary switch according to the received command, a step 104 of comparing the voltage level V int at the intermediate point 28 to a value of a second voltage threshold V th-O2, and if the voltage level V int at the intermediate point 28 is less than the value of the predetermined second voltage threshold V th-O2 during the switching command processing time range, a second type of malfunction is detected, i.e. the secondary switch is abnormally open.

[0066] The value of the second predetermined voltage threshold Vth-O2 is for example also between 20V and 50V.

[0067] The fact that the voltage level V int at the intermediate point 28 is lower than the second predetermined voltage threshold V th-O2 indicates an absence of voltage across the terminals of the secondary switch 20, whereas it should be closed according to the control sequence in nominal operation.

[0068] In one embodiment, the first voltage threshold and the second voltage threshold take the same value, also called the internal voltage reference, this value being for example equal to 20V.

[0069] In another embodiment, the first voltage threshold and the second voltage threshold take different values.

[0070] According to an alternative embodiment of the invention, in step 104, the voltage difference between an input voltage, as measured at the upstream connection point 6 (V6), and an output voltage, as measured at the downstream connection point 8 (V8), is determined. This voltage difference is compared with a predetermined voltage difference threshold Vth. If this voltage difference between the two voltages V6 and V8 exceeds this predetermined voltage difference threshold Vth, then a type II malfunction is detected, i.e., the secondary switch is abnormally open. The value of this predetermined voltage difference threshold Vth is, for example, also between 20V and 50V.

[0071] Then test 104 is followed by command step 88 of contactor blocking.

[0072] According to a preferred embodiment of the invention, the main switch remains in the position it was in before receiving the switching command so as not to risk being damaged during a switchover.

[0073] According to an alternative embodiment of the invention, the main switch is toggled to its open position, if it was not already in that position. The contactor is then locked in the open position. Advantageously, the contactor is thus locked in an open state, which is generally safer.

[0074] According to another alternative embodiment of the invention, the main switch is flipped to its closed position. This is particularly advantageous when a problem is detected during the contactor closing operation, as it avoids re-activating the main switch. It may also be more suitable depending on the load connected to the contactor (for example, a smoke extraction ventilation load where it is preferable for the ventilation to run continuously rather than being shut down in the event of a detected problem with the contactor).

[0075] In addition, preferably, step 88 is followed by the implementation 90 of an indicator of a malfunction state of the contactor (here malfunction of the second type), and therefore of the blocking state of the contactor.

[0076] It should be noted that, depending on the variants, it is possible to implement separate indicators to indicate a blocking state following a first type malfunction (abnormally closed secondary switch) and a blocking state following a second type malfunction (abnormally open secondary switch).

[0077] There figure 5 illustrates a variant of the detection of a malfunction of the secondary switch.

[0078] In this embodiment, the method includes monitoring 80 of the voltage level at the intermediate point 28 and comparing 82 to the first predetermined voltage threshold Vth-F1, which takes a reference voltage threshold value, for example of 20V.

[0079] The process then includes a filtering step 83, of predetermined duration, for example 2 ms, which validates the exceedance of the first predetermined voltage threshold Vth-F1 during the predetermined duration, thus preventing detection based on a point fault. It is then detected that the sinusoidal voltage signal at the intermediate point has a positive peak value greater than or equal to the value of the first voltage threshold during the predetermined duration (e.g., 2 ms). A peak counter is then incremented in the counter increment step 85.

[0080] It is then checked (step 87) whether the peak counter exceeds a predetermined number of overshoot periods NP, for example NP=3 or NP=5.

[0081] If this is the case, it is deduced that the peak value of the voltage signal at the intermediate point was detected as exceeding the first voltage threshold value for NP periods of the alternating voltage signal, i.e., for a duration greater than 15 ms, preferably greater than 40 ms, and therefore greater than the processing time of a switching command. This indicates that the secondary switch remained closed outside the time range for processing a switching command. A Type I malfunction (i.e., abnormally closed secondary switch) is then detected. Step 87 is then followed by step 86, which closes the main switch, and then by step 88, which locks the contactor, as previously described.

[0082] The peak counter is reset if the peak value of the voltage signal at the intermediate point remains below the value of the first voltage threshold for at least one period.

[0083] There figure 6 is a synoptic diagram of the main steps in a process for protecting a contactor of the type described with reference to the figure 1 , implemented by the contactor's calculation unit 30 for the detection of a malfunction of the main switch and a protection activation accordingly.

[0084] The steps described with reference to the figure 6 are implemented in addition to the steps for detecting a malfunction of the secondary switch.

[0085] Starting from the reception 102 of a switching command from the switch, the method includes monitoring 106 of the voltage level V out at the downstream connection point 8.

[0086] A distinction is made between an opening command and a closing command.

[0087] In the case of an opening command, the process further includes a step 108 of comparing the voltage level V out at the downstream connection point to the value of a third predetermined voltage threshold V th-F3 . during the time range of processing the command.

[0088] The value of the third voltage threshold is, for example, greater than or equal to 50 V, preferably greater than or equal to 200 V, which is a value close to the peak amplitude of the voltage signal.

[0089] If the voltage level V out at the downstream connection point exceeds the value of the third predetermined voltage threshold V th-F3 during the command processing time range, then the main switch 10 is abnormally closed. Otherwise, the contactor continues in nominal operating mode 200.

[0090] In one embodiment, a nominal operating indicator is implemented, for example, the indicator is a light located on a visible face (e.g. the front face) of the housing containing the contactor, and the nominal operating indicator is a chosen color of the light, for example green.

[0091] If the voltage level V out at the downstream connection point is greater than the value of the third predetermined voltage threshold V th-F3, step 108 is then followed by step 110, which involves a further attempt to open the contactor by implementing the sequence for switching to the open position. An opening attempt counter is initialized.

[0092] As an optional addition, an error indicator is implemented, for example, the indicator is a light located on a visible face of the housing containing the contactor, and the error indicator is a chosen color of the light, for example orange.

[0093] It is tested again in step 112 whether the main switch is open, and if the response is positive, the process returns to the nominal operating mode 200.

[0094] In case of a negative response, the opening attempt counter is incremented (step 114), then compared (step 116) to a predetermined number N of opening attempts.

[0095] For example, N is equal to 10.

[0096] If the opening attempt counter has not reached the predetermined number N of opening attempts, steps 110 to 116 are repeated.

[0097] If, after N opening attempts, the main switch has not opened, then a third-type malfunction (main switch abnormally closed) is detected, and the control unit commands 118 to lock the contactor. Locking the contactor results in the refusal to process any switching command to the contactor.

[0098] In addition, preferably, the process includes the implementation 120 of an indicator of the state of malfunction, and therefore of the blocking of the contactor.

[0099] Steps 118, 120 are analogous to steps 88, 90 previously described.

[0100] In the case of a closing command, the process further includes a step 122 of comparing the voltage level V out at the downstream connection point to a fourth predetermined voltage threshold V th-O4 during the time range of processing the command.

[0101] The value of the fourth voltage threshold is, for example, less than or equal to 50 V.

[0102] In one embodiment, the third voltage threshold and the fourth voltage threshold take the same value, for example between 50V and 100V, for example equal to 50V.

[0103] In another embodiment, the third voltage threshold and the fourth voltage threshold take different values.

[0104] If the voltage level V out at the downstream connection point is below the fourth predetermined opening voltage threshold V th-O4 during the command processing time range, then the main switch 10 is abnormally open. Otherwise, the contactor continues in nominal operating mode 200.

[0105] Step 122 is then followed by step 124, which involves a further attempt to close the contactor by executing the sequence for switching to the closed position. A closing attempt counter is initialized.

[0106] As an optional addition, an error indicator is implemented, for example, the indicator is a light located on a visible face of the housing containing the contactor, and the error indicator is a chosen color of the light, for example orange.

[0107] It is tested again in step 126 whether the main switch is closed, and if the response is positive, the process returns to the nominal operating mode 200.

[0108] In case of a negative response, the closing attempt counter is incremented (step 128), then compared (step 130) to a predetermined number M of closing attempts.

[0109] For example, M is equal to 3.

[0110] If the opening attempt counter has not reached the predetermined number M of closing attempts, steps 124 to 130 are repeated.

[0111] If, after M closing attempts, the main switch has not closed, then a type 4 malfunction (main switch abnormally open) is detected, and control unit 30 commands 118 to block the contactor. Blocking the contactor results in the refusal to process any switching command to the contactor.

[0112] In addition, preferably, the process includes the implementation 120 of an indicator of the state of malfunction, and therefore of the blocking of the contactor.

[0113] Steps 118, 120 are analogous to steps 88, 90 previously described.

[0114] Depending on the variants, it is envisaged to implement separate indicators to indicate a blocking state following a third type malfunction (abnormally closed main switch) and a blocking state following a fourth type malfunction (abnormally open main switch).

[0115] Advantageously, the described protection method allows protection in case of malfunctions, for example following a mechanical or electrical fault, of the secondary switch or the main switch, without the need to add many electronic components, and therefore maintaining the compactness of the contactor.

Claims

1. A method for protecting a contactor (2) intended, in a closed position, to establish, or, in an open position, to interrupt, the flow of a main electric current between a source of electrical energy (4) and at least one electrical load (5), the electrical energy being supplied at an alternating voltage, the contactor (2) having an upstream connection point (6) intended for connection to the electrical energy source (4) and a downstream connection point (8) intended for connection to said at least one electrical load (5), the contactor (2) comprising a main switch (10) connected between the upstream connection point (6) and the downstream connection point (8), and an assembly (16) comprising a secondary switch (20) connected in series with a unidirectional conductive component (18), said assembly (16) being connected between the upstream connection point (6) and the downstream connection point (8) in parallel with the main switch (10), the contactor (2) further comprising a computing unit (30) configured to receive contactor (2) switching commands and to control a sequence for opening and / or closing the main switch (10) and the secondary switch (20), as a function of the received switching command and a polarity direction of the alternating voltage, the secondary switch (20) being closed during a time interval for processing the switching command, the main switch (10) being controlled to open or close when the secondary switch is closed, the method being characterised in that it comprises implementation by the computing unit (30) of the steps of: - monitoring (80) of a voltage level at an intermediate point (28) located between the secondary switch (20) and the unidirectional conductive component (18), - when said voltage level is higher (82) than a value of a first predetermined voltage threshold, outside a time range for processing a switching command, detection (84, 87) of a malfunction of the secondary switch, and - control (86) for closing the main switch (10).

2. A method according to claim 1, in which the monitoring (80) of the voltage level is carried out continuously or with a selected time frequency.

3. A method according to any one of claims 1 or 2, further comprising, following receipt (102) of a switching command, a comparison (104) of the voltage level at the intermediate point with a value of a second voltage threshold, and if the voltage level at the intermediate point is less than the value of the second voltage threshold during the time range for processing the switching command, detection of malfunction of the secondary switch.

4. A method according to any one of claims 1 or 2, further comprising, following receipt (102) of a switching command, the steps for the: - determination of a voltage difference between an input voltage, as measured at the upstream connection point (6), and an output voltage, as measured at the downstream connection point (8), - comparison of the said voltage difference with a predetermined voltage difference threshold and, if the said voltage difference is greater than the predetermined voltage difference threshold, detection of a malfunction of the secondary switch.

5. A method according to any one of claims 1 to 4, further comprising, following detection of a malfunction of the secondary switch, a command (88) to block the contactor.

6. A method according to any one of claims 1 to 5, further comprising, following detection of malfunctioning of the secondary switch, implementation (90) of an indicator of the state of malfunctioning of the contactor.

7. A method according to any one of claims 1 to 6, further comprising, following receipt (102) of a command to switch to the open position, monitoring (106, 108) of a voltage level at the downstream connection point (8), and if said voltage level at the downstream connection point (8) is greater than a value of a third voltage threshold during the time range for processing the command, implementation of a predetermined number N of opening attempts, and an indication of the error state of the contactor.

8. A method according to claim 7, in which if after N opening attempts, the voltage level at the downstream connection point remains higher than the value of the third voltage threshold, the contactor is blocked (118) and an indication of a malfunctioning state of the contactor is implemented (120).

9. A method according to one of claims 1 to 8, further comprising, following receipt (102) of a command to switch to the closed position, monitoring (106, 122) of a voltage level at the downstream connection point (8), and if said voltage level at the downstream connection point (8) is less than a value of a fourth voltage threshold during the time range for processing the command, implementing a predetermined number M of closure attempts, and indicating the error state of the contactor.

10. A method according to claim 9, in which if, after M closure attempts, the voltage level at the downstream connection point (8) remains below the value of the fourth voltage threshold, command (118) to block the contactor and implementation (120) of an indication of a malfunctioning state of the contactor.

11. A contactor (2) intended, in a closed position, to establish, or, in an open position, to interrupt, the flow of a main electric current between a source of electrical energy (4) and at least one electrical load (5), the electrical energy being supplied at an alternating voltage, the contactor (2) having an upstream connection point (6) intended for connection to the electrical energy source (4) and a downstream connection point (8) intended for connection to said at least one electrical load (5), the contactor comprising a main switch (10) connected between the upstream connection point (6) and the downstream connection point (8), and an assembly (16) comprising a secondary switch (20) connected in series with a unidirectional conductive component (18), said assembly (16) being connected between the upstream connection point (6) and the downstream connection point (8) in parallel with the main switch (10), the contactor further comprising a computing unit (30) configured to receive contactor (2) switching commands and to control a sequence for opening and / or closing the main switch (10) and the secondary switch (20), as a function of the received switching command and a polarity direction of the alternating voltage, the secondary switch (20) being closed during a time interval for processing the switching command, the main switch (10) being controlled to open or close when the secondary switch is closed, characterised in that the computing unit (30) is configured to implement a protection method in accordance with claims 1 to 10.

12. A contactor as claimed in claim 11, further comprising a first voltage measurement module (22) at the upstream connection point (6), a second voltage measurement module (24) at the downstream connection point (8) and a third voltage measurement module (26) at the intermediate point (28), each of said modules being connected to the computing unit (30).

13. A contactor according to claims 10 to 12, wherein the main switch (10) is a bistable electromechanical relay and the secondary switch (20) is a monostable electromechanical relay.

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