Method for protecting contactor and corresponding contactor

Abstract

The contactor (2) comprises a main switch (10) connected between an upstream connection point (6) and a downstream connection point (8), and the main switch is connected in parallel with an assembly (16) comprising a secondary switch (20) connected in series with a unidirectionally conductive member (18). The computing unit (30) is configured to receive the switching command, control an opening and / or closing sequence of the primary switch and the secondary switch, the secondary switch being closed during a time range for processing the switching command, the primary switch operating when the secondary switch is closed. The computing unit monitors the voltage level at the intermediate point (28) and detects a fault of the secondary switch and commands the main switch to close when the voltage level exceeds a predetermined first voltage threshold outside the switching command processing time range.

Description

Technical Field

[0001] The invention relates to a method for protecting a contactor intended to establish, in a closed position, or to interrupt, in an open position, the flow of a main current between an electrical power source provided at an alternating voltage and at least one electrical load.

[0002] The invention also relates to a contactor for implementing the protection method. Background Art

[0003] The present invention belongs to the field of electrical contactors, which are generally used to establish or interrupt the flow of current between a power source and one or more electrical loads. In other words, the contactor is used to supply power to the electrical load, which load can be any type of electrical equipment, such as a motor, a heating device or a lighting device.

[0004] Such contactors open and close in response to a command, for example manually or remotely. Advantageously, the command is electrical.

[0005] The opening and closing operations use electrical contacts that include contact pads that are susceptible to physical wear after a certain number of operations.

[0006] Furthermore, it is preferred to design contactors with small dimensions so that they occupy the smallest possible space in a housing or a switchboard, while reducing wear to increase their lifespan.

[0007] Patent FR 3 099 289 describes a contactor with improved electrical durability, comprising two switches, a first switch being a main switch, connected between an upstream connection point for connection to a power source and a downstream connection point for connection to one or more electrical loads, and an assembly formed by a second switch, a secondary switch, connected in series with a unidirectional conductive member, the assembly being connected in parallel with the main switch. The patent describes a method for controlling the main switch and the secondary switch, the method ensuring that during nominal operation, when the secondary switch is closed, the main switch is switched to open or closed, so that the switching of the main switch is performed without current switching and therefore without any significant effect on the contacts of this switch. Likewise, the switching of the secondary switch is performed without current switching and therefore without any significant effect on the contacts of this switch due to the unidirectional conductive member and the switching command during the blocking state of this member.

[0008] Therefore, during nominal operation, such contactors are more robust and have an increased lifespan.

[0009] In order to ensure a small overall volume and obtain a contactor with smaller dimensions, it is beneficial to choose switches with different specifications, in particular a main switch supporting the main current, and a secondary switch supporting a smaller current, assuming that the secondary switch is intended to support the main current for a very short time, for example a time less than half a cycle of the main current (i.e. less than 10 milliseconds for a current of 50 Hz).

[0010] However, with such contactors, a possible electrical fault or malfunction may result in damage to one or the other switch, in particular to the secondary switch, which is then no longer able to perform the originally intended function.

[0011] There is therefore a need to improve the protection of such contactors against faults while retaining the advantages of robustness and compactness. Summary of the invention

[0012] To this end, the present invention relates to a method for protecting a contactor, the contactor being intended to establish in a closed position or to interrupt in an open position the flow of a main current between a power source and at least one electrical load, the power source being provided under an alternating voltage, the contactor having an upstream connection point for connection to the power source and a downstream connection point for connection to the at least one electrical load, the contactor comprising a main switch connected between the upstream connection point and the downstream connection point, and a component comprising a secondary switch connected in series with a unidirectional conductive component, the component being connected in parallel with the main switch between the upstream connection point and the downstream connection point, the contactor also comprising a calculation unit configured to receive a switching command of the contactor and to control the opening and / or closing sequence of the main switch and the secondary switch based on the received switching command and the polarity direction of the alternating voltage, the secondary switch being closed within a time range for processing the switching command, and the main switch being commanded to open or close when the secondary switch is closed.

[0013] The method comprises the following steps implemented by a computing unit:

[0014] monitoring the voltage level at a point midway between the secondary switch and the unidirectional conducting component,

[0015] detecting a failure of the secondary switch when the voltage level exceeds a predetermined first voltage threshold outside the switching command processing time range, and

[0016] Command to close the main switch.

[0017] Advantageously, monitoring of the voltage level makes it possible to detect an abnormal closing of the secondary switch and to take immediate measures aimed at avoiding subsequent damage to the contactor.

[0018] The method for protecting a contactor according to the present invention may have one or more of the following features, which may be employed independently or in any permissible combination.

[0019] The voltage level is monitored continuously or at a selected time frequency.

[0020] The method further comprises:

[0021] after receiving the switching command, comparing the voltage level at the midpoint with a second voltage threshold, and detecting a failure of the secondary switch if the voltage level at the midpoint is less than the second voltage threshold during a time range for processing the switching command;

[0022] After receiving the switch command, perform the following steps:

[0023] determining the voltage difference between the input voltage measured at the upstream connection point and the output voltage measured at the downstream connection point,

[0024] comparing the voltage difference to a predetermined voltage difference threshold, and detecting a failure of the secondary switch if the voltage difference exceeds the predetermined voltage difference threshold;

[0025] After detecting a fault in the secondary switch, a command is issued to block the contactor;

[0026] After detecting a fault in the secondary switch, indicating a fault condition of the contactor;

[0027] After receiving a command to switch to the open position, monitoring a voltage level at the downstream connection point and, if during a time frame for processing the command, the voltage level at the downstream connection point exceeds a third voltage threshold, performing a predetermined number N of disconnection attempts and indicating an error state of the contactor;

[0028] If after N disconnection attempts, the voltage level at the downstream connection point still exceeds the third voltage threshold, commanding blocking of the contactor and indicating a fault state of the contactor;

[0029] After receiving a command to switch to the closed position, monitoring a voltage level at the downstream connection point and, if the voltage level at the downstream connection point is less than a fourth voltage threshold during a time frame for processing the command, performing a predetermined number M of closing attempts and indicating an error state of the contactor;

[0030] If after M closing attempts the voltage level at the downstream connection point is still below the fourth voltage threshold, blocking of the contactor is commanded and a fault state of the contactor is indicated.

[0031] The present invention also relates to a contactor, which is used to establish the flow of main current between a power supply and at least one electrical load in a closed position or to interrupt the flow of main current between a power supply and at least one electrical load in an open position, the power supply being provided under an alternating voltage, the contactor having an upstream connection point for connecting to the power supply and a downstream connection point for connecting to the at least one electrical load, the contactor comprising a main switch connected between the upstream connection point and the downstream connection point, and a component comprising a secondary switch connected in series with a unidirectional conductive component, the component being connected in parallel with the main switch between the upstream connection point and the downstream connection point, the contactor also comprising a calculation unit, the calculation unit being configured to receive a switching command for the contactor, and to control the opening and / or closing sequence of the main switch and the secondary switch based on the received switching command and the polarity direction of the alternating voltage, the secondary switch being closed within a time range for processing the switching command, and when the secondary switch is closed, the main switch being commanded to open or close, the calculation unit being configured to implement the protection method briefly described above.

[0032] The contactor also comprises a first module for measuring the voltage at the upstream connection point, a second module for measuring the voltage at the downstream connection point and a third module for measuring the voltage at the intermediate point, each of said modules being connected to the calculation unit.

[0033] In one embodiment, the primary switch is a bistable electromechanical relay and the secondary switch is a monostable electromechanical relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other characteristics and advantages of the invention will emerge from the following description given by way of indicative and non-limiting examples, with reference to the accompanying drawings, in which:

[0035] Figure 1 is a block diagram of a contactor according to one embodiment;

[0036] Figure 2 is a diagram showing the sequence of states of the switch after a command to close the contactor during nominal operation;

[0037] Figure 3 is a diagram showing the sequence of states of the switch after a command to open the contactor during nominal operation;

[0038] Figure 4 is a summary of the main steps of a method for protecting a contactor for detecting secondary switch faults;

[0039] Figure 5 Another embodiment of certain steps of a method for protecting a contactor for detecting a secondary switch failure is shown;

[0040] Figure 6 This is an outline of the main steps of a method for protecting a contactor for detecting a main switch failure. DETAILED DESCRIPTION

[0041] Figure 1 A contactor 2 is shown for establishing in a closed position or interrupting in an open position the flow of a main current I between a power source 4 provided at an alternating voltage and at least one electrical load 5 .

[0042] exist Figure 1 In the figure, a single electric load 5 has been shown, it should be understood that the electric load 5 may be composed of one or more electrical devices, such as a motor, a heating resistor, a lighting device or any other device that needs to be connected to a power supply.

[0043] The power source 4 is, for example, a power distribution network or a generator, and provides a predetermined AC voltage Ug, for example, 240 V and 50 Hz.

[0044] The contactor 2 comprises an upstream connection point 6 intended to be connected to an electrical power source 4 and a downstream connection point 8 intended to be connected to an electrical load 5 .

[0045] The power source 4 is firstly connected to an upstream connection point 6 and secondly to an electrical load 5. The link between the power source 4 and the electrical load 5 is, for example, a phase line or a neutral line.

[0046] For the sake of clarity, the AC voltage Ug is referenced relative to a potential reference point 12 , which may or may not be integrated in the contactor.

[0047] The contactor 2 further comprises a main switch 10 connected between the upstream connection point 6 and the downstream connection point 8 .

[0048] The contactor 2 further comprises 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 comprising a secondary switch 20 connected in series with a unidirectionally conducting member 18 .

[0049] exist Figure 1 In the embodiment of FIG. 5 , the unidirectional conductive component 18 is a diode, the anode of which is arranged on the side of the current source 4, and the cathode of which is arranged on the side of the electric load 5. As a variation, the unidirectional conductive component 18 may be a thyristor.

[0050] The contactor 2 also includes a first module 22 for measuring the voltage at the upstream connection point 6, a second module 24 for measuring the voltage at the downstream connection point 8, and a third module 26 for measuring the voltage at the intermediate point 28, which is located between the secondary switch 20 and the unidirectional conductive component 18, more specifically, downstream of the secondary switch 20 and upstream of the unidirectional conductor 18.

[0051] The contactor 2 further comprises a computing unit 30 , which is realized, 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 (Application Specific Integrated Circuit).

[0052] The first, second and third voltage measurement modules provide voltage measurement values ​​to the calculation unit 30 .

[0053] The computing unit 30 is configured to receive a switching command of 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.

[0054] In one embodiment, the computing unit 30 is programmed, either remotely through an application program or locally through a human-machine interface, to implement a switching command triggered, for example, by an internal clock of the computing unit 30 .

[0055] 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 including a voltage divider bridge, and the calculation unit 30 performs additional calculations to obtain measurements of the corresponding voltage levels.

[0056] During nominal operation, the calculation unit 30 is configured to control the opening and / or closing sequence of the secondary switch 20 and the main switch 10 based on the received switching command and the polarity direction of the AC voltage Ug when receiving the switching command of the contactor 2, while performing the opening and closing operations of each switch 10, 20 with a low current at the terminals of the switches 10, 20 in order to protect them from mechanical wear. This nominal operation will be described in detail below, more specifically with reference to Figure 2 and 3 .

[0057] In one embodiment, the main switch 10 is an electromechanical relay, comprising at least one moving contact controlled by a coil to establish contact with a fixed contact. Such an electromechanical relay is a component that takes up little space, is not very expensive, and has a low mechanical resistance between the closed contacts.

[0058] The secondary switch 20 is also preferably an electromechanical relay.

[0059] In a preferred embodiment, the main switch 10 is a bistable electromechanical relay and the secondary switch 20 is a monostable electromechanical relay, which occupies less space than a bistable electromechanical relay. Therefore, the overall volume of the contactor 2 is smaller.

[0060] Furthermore, the main switch 10 is preferably 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 may advantageously be smaller in size than the main switch 10, for example five to ten times smaller in volume, since it is intended to support the main current I for a very short time, for example less than half a cycle of the main current I (i.e. a time less than 10 ms for a current of 50 Hz), whereas the main switch 10 must support the main current I for an indefinite time, depending on the time between the commands to close and open the switch.

[0061] Figure 2 In the first graph 50, a sinusoidal signal of an alternating voltage Ug is shown as a function of time, and the polarity direction of the alternating voltage represented by the symbols "+" and "-". The sinusoidal signal of the alternating voltage has a time period T. For half a period T1 (or T3), the alternating voltage Ug is positive and the polarity direction is positive. For the subsequent half period T2 (or T4), the alternating voltage Ug is negative and the polarity direction is negative. The sum of the half periods T1 and T2 is equal to the period T.

[0062] Figure 2 The open or closed state of the main switch 10 and the secondary switch 20 during the half cycles T1, T2, T3, T4 is shown, forming a state sequence after a switching command to close the contactor 2, ie a command for the contactor 2 to switch from the open state to the closed state.

[0063] In order to better protect the contacts of switches 10 and 20 from electrical wear (wear of contact pads), the secondary switch 20 is operated when the unidirectional conductive component 18 is in a blocked state, that is, when the polarity direction of the AC voltage Ug applies a reverse voltage to the terminals of the unidirectional conductive component 18.

[0064] During the half cycle T1, the polarity direction of the AC voltage Ug is positive, and the two switches 10, 20 are open. During the subsequent half cycle T2, the polarity direction of the AC voltage Ug is negative, the unidirectional conductive component 18 is in a blocked state, and the secondary switch 20 is closed. Due to the blocked state of the unidirectional conductive component 18, the closing operation of the secondary switch 20 has no significant effect on the contacts of the switch. The secondary switch 20 is in a period called the switching command processing time range T CAfter the secondary switch 20 is closed, during the half period T3, when the polarity direction of the AC voltage Ug is positive, the main current flows through the secondary switch 20 and the unidirectional conductive component 18, which is then turned on, and the voltage across the terminals of the main switch 10 is low. The calculation unit 30 then commands the main switch 10 to close, and the main current I then flows through the main switch 10. During the subsequent half period T4, the polarity direction of the AC voltage Ug is negative, the unidirectional conductive component 18 is in a blocked state, and the secondary switch 20 is then opened without any deterioration of its contacts, and the current is zero because it is blocked by the component 18. The contactor 2 then finds itself in the closed position according to the received command.

[0065] Figure 2 The open / closed state of the secondary switch 20 is also schematically shown as a function of time in a second graph 52 and the open / closed state of the main switch 10 is schematically shown as a function of time in a third graph 54 in the case of processing a command to close the contactor.

[0066] In a similar way, Figure 3 The open or closed state of the main switch 10 and the secondary switch 20 is shown over half periods T5, T6, T7, T8 during nominal operation, forming a sequence of states following a switching command to open the contactor 2, i.e. a command for the contactor 2 to switch from the closed state to the open state. Initially, the main switch 10 is closed and the secondary switch 20 is open.

[0067] Figure 3 In the first graph 56, a sinusoidal signal of the alternating voltage Ug is shown as a function of time, and the polarity direction of the alternating voltage represented by the symbols "+" and "-". The sinusoidal signal of the alternating voltage has a time period T. For half a period T5 (or T7), the alternating voltage Ug is positive and the polarity direction is positive. For the subsequent half period T6 (or T8), the alternating voltage Ug is negative and the polarity direction is negative. The second graph 58 schematically shows the open / closed state of the secondary switch as a function of time during nominal operation, in the case of processing a command to open the contactor, and the third graph 60 shows the open / closed state of the main switch as a function of time.

[0068] During the half cycle T5, the polarity direction of the AC voltage Ug is positive, the main switch 10 is closed, and the secondary switch 20 is open. During the subsequent half cycle T6, the polarity direction of the AC 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, the closing operation of the secondary switch 20 has no significant effect on the contacts of the switch. The secondary switch 20 is in the switching command processing time range T CAfter the secondary switch 20 is closed, during the half cycle T7, when the polarity direction of the AC voltage Ug is positive, the calculation unit 30 then commands the main switch 10 to be opened, and the main current I then flows through the secondary switch 20 and the unidirectional conductive component. During the next half cycle T8, the polarity direction of the AC voltage Ug is negative, the unidirectional conductive component 18 is in a blocked state, and then the secondary switch 20 is opened. Then, the contactor 2 finds itself in the open position according to the received command.

[0069] From the above Figure 2 and 3 It can be clearly seen from the description that during nominal operation, within the switching command processing time range and in the orthogonal change of the voltage, when the secondary switch 20 is closed, the main switch 10 is commanded to open or close.

[0070] The purpose of the method for protecting a contactor is to detect and protect the contactor in the event of a failure of one of the switches, ie when one of the switches does not function as it does during nominal operation.

[0071] In particular, the protection method detects two types of faults in the secondary switch:

[0072] The first type of fault, where the secondary switch is abnormally closed, or

[0073] The second type of fault is where the secondary switch is abnormally disconnected.

[0074] Specifically, after a mechanical or electrical fault, such as after a current overload, or due to the fact that one of its contacts becomes resistive due to, for example, a shock wave, the secondary switch 20 may remain abnormally closed. In this case, the secondary switch 20 may be damaged, particularly when the secondary switch 20 is not dimensioned to support the main current for a long time.

[0075] Secondary switch 20 may remain abnormally disconnected, for example if it is damaged after a mechanical or electrical failure. In this case, secondary switch 20 may not ensure the function of protecting (switching current / voltage to zero) the contacts of the main switch from wearing out in the nominal operating mode.

[0076] Likewise, the protection method detects two types of main switch failures:

[0077] The third type of fault is when the main switch is abnormally closed, or

[0078] The fourth type of fault is that the main switch is abnormally disconnected.

[0079] Figure 4 is implemented by the contactor's calculation unit 30 for protecting the reference Figure 1An overview of the main steps of a method for a contactor of this type is described. These steps involve the detection of secondary switch faults and the subsequent protection.

[0080] The method includes monitoring 80 a voltage level at the intermediate point 28 (ie, the voltage downstream of the secondary switch 20 ), which is provided by the third voltage measurement module 26 .

[0081] The monitoring 80 of the voltage level at the intermediate point 28 is performed continuously or at a given time frequency, asynchronously with any processing 100 of the switching command of the contactor, that is to say independently of any possible ongoing processing 100 of the received switching command. For example, the monitoring 80 of the voltage level at the intermediate point 28 is performed at a time frequency of the order of 10 to 30 milliseconds. A filtering (or temporalization) of 30 to 50 milliseconds may be performed to avoid detecting false faults (such as temporary surges).

[0082] Next, check the voltage level V at the midpoint 28. int Whether the predetermined first voltage threshold V is exceeded outside the switching command processing time range (and therefore outside the closing in the opening and closing sequence after receiving the command) th-F1 .

[0083] exist Figure 4 In the embodiment of FIG. 8 , the check is performed in two steps; first, in step 82 , the voltage level V at the intermediate point 28 is checked. int Whether it exceeds the predetermined first voltage threshold V th-F1 , and if V int >V th-F1 , then it is also checked (step 84) whether the switching command processing range is in progress. The predetermined first voltage threshold V th-F1 For example between 20V and 50V.

[0084] exceeds the predetermined first voltage threshold V th-F1 This indicates that a voltage is present at the terminals of the secondary switch 20 .

[0085] If there is a voltage at the terminals of the secondary switch 20 that is outside the range that the switching command can handle, it is inferred that the secondary switch is abnormally closed; it is in a first type fault state.

[0086] Step 84 is followed by step 86, commanding the main switch to close, and then commanding the contactor to block 88. Blocking of the contactor results in a refusal to process any switching command for the contactor.

[0087] Furthermore, the method preferably comprises indicating 90 a fault state, and thus a blocking state of the contactor. In this particular case, the blocking is blocking to a closed state. For example, the indicator is an indicator light located on a visible face of a housing containing the contactor, preferably a front face visible to a user, and the fault indicator, here a fault of the first type, is a selected color of the indicator light, for example red, and / or a flashing state of the indicator light. Of course, other variations of the fault state indicator of the contactor are also possible.

[0088] In the switching command processing 100, after receiving the switching command 102, in addition to implementing the opening and / or closing sequence of the primary switch and the secondary switch based on the received command, the method also includes setting the voltage level V at the intermediate point 28 to int The second voltage threshold V th-O2 The comparison step 104 is performed and if during the time frame for processing the switching command, the voltage level V at the intermediate point 28 int is less than a predetermined second voltage threshold V th-O2 , then a second type of fault state is detected, that is, the secondary switch is abnormally disconnected.

[0089] The predetermined second voltage threshold V th-O2 For example, it also includes between 20V and 50V.

[0090] The voltage level V at the midpoint 28 int is less than a predetermined second voltage threshold V th-O2 The fact that φ ∈ φ indicates that no voltage is present across the terminals of the secondary switch 20 , whereas during nominal operation it should be closed according to the switching sequence.

[0091] In one embodiment, the first voltage threshold and the second voltage threshold have the same value, also referred to as an internal voltage reference, which is equal to 20V, for example.

[0092] In another embodiment, the first voltage threshold and the second voltage threshold take different values.

[0093] According to an alternative embodiment of the invention, during step 104, the voltage difference between the input voltage (V6) measured at the upstream connection point 6 and the output voltage (V8) measured at the downstream connection point 8 is determined. This voltage difference is compared with a predetermined voltage difference threshold V th If the voltage difference between the two voltages V6 and V8 exceeds the predetermined voltage difference threshold V th , a second type of fault state is detected, that is, the secondary switch is abnormally disconnected. The predetermined voltage difference threshold V th The value of is also comprised between 20 V and 50 V, for example.

[0094] Test 104 is followed by step 88 of commanding the contactors to block.

[0095] According to a preferred embodiment of the invention, the main switch is kept in the position before receiving the switching command to avoid the risk of being damaged during switching.

[0096] According to an alternative embodiment of the invention, if the main switch is not already in the off position, it is switched to the off position. The contactor is then locked in the off position. Advantageously, the contactor is thus blocked in the off state, which is generally safer.

[0097] According to another alternative embodiment of the invention, the main switch is switched to its closed position. This is particularly advantageous during problem detection during contactor closing operation, since this avoids repeated use of the main switch. This can even be done depending on the load connected to the contactor (for example a load of the smoke ventilation type, for which it is better for the ventilation to run permanently than to stop when a problem is detected on the contactor).

[0098] Furthermore, step 88 is preferably followed by an indication 90 of a fault state of the contactor (here a fault of the second type), and thus of a blocking state of the contactor.

[0099] It should be noted that, according to a variant, different indicators may be implemented to indicate the blocking state after a first type of fault (the secondary switch is abnormally closed) and the blocking state after a second type of fault (the secondary switch is abnormally open).

[0100] Figure 5 A variation for detecting secondary switch failure is shown.

[0101] In this embodiment, the method comprises monitoring 80 the voltage level at the intermediate point 28 and comparing said voltage level with a predetermined first voltage threshold V th-F1 The comparison 82 is performed, the first voltage threshold V th-F1 A reference voltage threshold is used, for example 20V.

[0102] The method then comprises filtering 83 for a predetermined time (for example 2 ms), which makes it possible to verify that a predetermined first voltage threshold V th-F1 , which makes it possible to avoid detecting a one-time fault. It is then detected that the sinusoidal voltage signal at the midpoint has a peak positive value exceeding or equal to the first voltage threshold for a predetermined time (e.g. 2ms). Then, in a counter increment step 85, the peak counter is incremented.

[0103] It is then checked (step 87) whether the peak counter exceeds a predetermined number of exceedance periods NP, for example NP=3 or NP=5.

[0104] If this is the case, it is inferred that during NP cycles of the AC voltage signal, the peak value of the voltage signal at the midpoint has been detected to exceed the first voltage threshold, i.e., for a time greater than 15 ms, preferably for a time greater than 40 ms, and thus greater than the time for processing the switching command, which indicates that the secondary switch remains closed outside the switching command processing time range. A first type of fault is then detected (i.e., the secondary switch is abnormally closed). Step 87 is followed by step 86, commanding the main switch to close, and then commanding 88 the contactor to block, as described above.

[0105] If the peak value of the voltage signal at the intermediate point remains less than the first voltage threshold for at least one cycle, the peak value counter is reset to zero.

[0106] Figure 6 It is used to protect the reference Figure 1 An overview of the main steps of a method for a contactor of the type described, which method is implemented by a computing unit 30 of the contactor for detecting a failure of a main switch and subsequent protection.

[0107] In addition to the steps for detecting secondary switch failure, reference Figure 6 Describe the steps.

[0108] Starting with receiving 102 a switching command for the switch, the method comprises monitoring 106 a voltage level V at the downstream connection point 8. out .

[0109] There is a distinction between opening commands and closing commands.

[0110] In the case of a disconnect command, the method further comprises a step 108 of increasing the voltage level V at the downstream connection point during the time frame for processing the command. out and a predetermined third voltage threshold V th-F3 Make a comparison.

[0111] The third voltage threshold is, for example, greater than or equal to 50 V, and preferably greater than or equal to 200 V, which is close to the peak amplitude of the voltage signal.

[0112] If during the time frame for processing the command, the voltage level V at the downstream connection point out exceeds a predetermined third voltage threshold V th-F3 , the main switch 10 is abnormally closed. If this is not the case, the contactor continues in the nominal operating mode 200.

[0113] In one embodiment, an indicator of nominal operation is implemented, for example, the indicator is an indicator light located on a visible surface (eg, front face) of a housing containing the contactor, and the indicator of nominal operation is a selected color of the indicator light, such as green.

[0114] If the voltage level at the downstream connection point V out exceeds a predetermined third voltage threshold V th-F3 , then step 108 is followed by step 110, attempting to open the contactor again by executing the sequence to enter the open position. The opening attempt counter is initialized.

[0115] As an optional addition, an error indicator is implemented, for example, the indicator is a light indicator located on the visible face of the housing containing the contactor, and the error indicator is a selected color of the light indicator, for example orange.

[0116] In step 112 it is again tested whether the main switch is open and in case of a positive response the method returns to the nominal operating mode 200 .

[0117] In case of a negative response, a switch-on attempt counter is incremented (step 114) and then compared with a predetermined number N of switch-off attempts (step 116).

[0118] For example, N is equal to 10.

[0119] If the disconnection attempt counter has not reached the predetermined number N of disconnection attempts, steps 110 to 116 are repeated.

[0120] If at the end of N opening attempts the main switch has not opened, a third type of fault is detected (abnormal closing of the main switch) and the calculation unit commands 118 blocking of the contactor. Blocking of the contactor results in a refusal to process any switching command of the contactor.

[0121] Furthermore, the method preferably comprises indicating 120 a fault state and thus blocking of the contactor.

[0122] Steps 118 and 120 are similar to steps 88 and 90 described above.

[0123] In the case of a closing command, the method further comprises a step 122 of increasing the voltage level V at the downstream connection point during the time frame for processing the command. out and a predetermined fourth voltage threshold V th-O4 Make a comparison.

[0124] The fourth voltage threshold is, for example, less than or equal to 50V.

[0125] In one embodiment, the third voltage threshold and the fourth voltage threshold have the same value, for example, included between 50V and 100V, for example, equal to 50V.

[0126] In another embodiment, the third voltage threshold and the fourth voltage threshold have different values.

[0127] If during the time frame of processing the command, the voltage level V out is less than the predetermined fourth disconnect voltage threshold V th-O4 , the main switch 10 is abnormally disconnected. If this is not the case, the contactor continues in the nominal operating mode 200.

[0128] Step 122 is followed by step 124 where an attempt is made to close the contactor again by executing a sequence to enter the closed position. A closing attempt counter is initialized.

[0129] As an optional addition, an error indicator is implemented, for example, the indicator is a light indicator located on the visible face of the housing containing the contactor, and the error indicator is a selected color of the light indicator, for example orange.

[0130] It is tested again in step 126 whether the main switch is closed and in case of a positive response the method returns to the nominal operating mode 200 .

[0131] In case of a negative response, a closing attempt counter is incremented (step 128) and then compared with a predetermined number M of closing attempts (step 130).

[0132] For example, M is equal to 3.

[0133] If the closing attempt counter has not reached the predetermined number M of closing attempts, steps 124 to 130 are repeated.

[0134] If the main switch is not closed at the end of M closing attempts, a fourth type of fault is detected (abnormal opening of the main switch) and the calculation unit 30 commands 118 blocking of the contactor. Blocking of the contactor results in a refusal to process any switching command of the contactor.

[0135] Furthermore, the method preferably comprises indicating 120 a fault state and thus blocking of the contactor.

[0136] Steps 118 and 120 are similar to steps 88 and 90 described above.

[0137] According to a variant, it is contemplated to implement different indicators to indicate the blocking state after the third type of fault (the main switch is abnormally closed) and the blocking state after the fourth type of fault (the main switch is abnormally opened).

[0138] Advantageously, the protection method described allows providing protection in the event of a fault in the secondary switch or in the main switch, for example following a mechanical or electrical fault, without adding many electronic components, thus while maintaining the compactness of the contactor.

Claims

1. A method for protecting a contactor (2), the contactor being intended to establish in a closed position or to interrupt in an open position the flow of a main current between a power source (4) and at least one electrical load (5), the power source being provided at an alternating voltage, the contactor (2) having an upstream connection point (6) for connection to the power source (4) and a downstream connection point (8) for connection to the 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 comprising a secondary switch connected in series with a unidirectional conductive member (18). The contactor (20) comprises a component (16) of a switch (20), wherein the component (16) is connected in parallel with the main switch (10) between the upstream connection point (6) and the downstream connection point (8), the contactor (2) further comprising a calculation unit (30), the calculation unit being configured to receive a switching command for the contactor (2), and to control the opening and / or closing sequence of the main switch (10) and the secondary switch (20) based on the received switching command and the polarity direction of the AC voltage, the secondary switch (20) being closed within a time range for processing the switching command, and the main switch (10) being commanded to open or close when the secondary switch is closed, The method is characterized in that it comprises the following steps implemented by a computing unit (30): monitoring (80) a voltage level at an intermediate point (28) between the secondary switch (20) and the unidirectional conductive member (18), When the voltage level exceeds (82) a predetermined first voltage threshold outside the switching command processing time range, a fault of the secondary switch is detected (84, 87), and Command (86) closing of the main switch (10).

2. The method according to claim 1, characterized in that Monitoring of the voltage level is performed continuously or at a selected time frequency (80).

3. The method according to any one of claims 1 and 2 further comprises, after receiving (102) a switching command, comparing (104) the voltage level at the midpoint with a second voltage threshold, and detecting a fault in the secondary switch if the voltage level at the midpoint is less than the second voltage threshold during a time range for processing the switching command.

4. The method according to any one of claims 1 and 2, further comprising the following steps after receiving (102) the switching command: determining a voltage difference between an input voltage measured at an upstream connection point (6) and an output voltage measured at a downstream connection point (8), The voltage difference is compared to a predetermined voltage difference threshold, and if the voltage difference exceeds the predetermined voltage difference threshold, a failure of the secondary switch is detected.

5. The method according to any one of claims 1 to 4, further comprising, after detecting a failure of the secondary switch, commanding (88) blocking of the contactor.

6. The method according to any one of claims 1 to 5, further comprising, after detecting a failure of the secondary switch, indicating (90) a fault condition of the contactor.

7. The method according to any one of claims 1 to 6 further comprises, after receiving (102) a command to switch to the disconnected position, monitoring (106, 108) a voltage level at a downstream connection point (8), and if during a time range for processing the command, the voltage level at the downstream connection point (8) exceeds a third voltage threshold, performing a predetermined number N of disconnection attempts and indicating an error state of the contactor.

8. The method according to claim 7, wherein: If after N disconnection attempts the voltage level at the downstream connection point still exceeds the third voltage threshold, blocking of the contactor is commanded (118) and a fault condition of the contactor is indicated (120).

9. The method according to any one of claims 1 to 8 further comprises, after receiving (102) a command to switch to the closed position, monitoring (106, 122) a voltage level at a downstream connection point (8), and if during a time range for processing the command, the voltage level at the downstream connection point (8) is less than a fourth voltage threshold, performing a predetermined number M of closing attempts and indicating an error state of the contactor.

10. The method according to claim 9, wherein: If after M closing attempts the voltage level at the downstream connection point (8) is still less than the fourth voltage threshold, blocking of the contactor is commanded (118) and a fault state of the contactor is indicated (120).

11. A contactor (2) for establishing in a closed position or interrupting in an open position the flow of a main current between a power source (4) and at least one electrical load (5), the power source being provided at an alternating voltage, the contactor (2) having an upstream connection point (6) for connection to the power source (4) and a downstream connection point (8) for connection to the 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 a secondary switch (20) connected in series with a unidirectional conductive member (18). A component (16) is connected in parallel with the main switch (10) between the upstream connection point (6) and the downstream connection point (8), the contactor also comprising a calculation unit (30) configured to receive a switching command for the contactor (2) and control the opening and / or closing sequence of the main switch (10) and the secondary switch (20) based on the received switching command and the polarity direction of the AC voltage, the secondary switch (20) being closed within a time range for processing the switching command, and the main switch (10) being commanded to open or close when the secondary switch is closed, It is characterized in that The computing unit (30) is configured to implement the protection method according to any one of claims 1 to 10.

12. The contactor according to claim 11 further comprises a first module (22) for measuring the voltage at the upstream connection point (6), a second module (24) for measuring the voltage at the downstream connection point (8) and a third module (26) for measuring the voltage at the intermediate point (28), each of said modules being connected to a calculation unit (30).

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

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