METHOD FOR TESTING THE DIFFERENTIAL PROTECTION, DIFFERENTIAL PROTECTION DEVICE AND ELECTRICAL DEVICE COMPLETING SUCH A DEVICE

Description

TECHNICAL FIELD

[0001] The invention relates to a differential protection test method having a first differential protection chain, a second differential protection chain, and a processing unit.

[0002] The invention also relates to a differential protection device comprising: a first differential protection chain, a second differential protection chain, a test device for testing said differential protection chains, and a processing unit connected to the second differential protection chain.

[0003] The invention also relates to an electrical protection device comprising main contacts, a mechanism for opening said main contacts, main conductors connected in series with said main contacts and a differential protection device having at least two differential protection chains. STATE OF THE ART

[0004] Signal injection is a known method for testing residual current protection devices. The purpose of these tests is to verify the operation of the measurement and tripping chain. Most tests involve generating a residual current fault signal and observing whether an electrical device trips or opens.

[0005] WO 2012 / 040750 A1 and US 2010 / 295568 A1 describe examples of differential protection devices including test means.

[0006] Existing test equipment is insufficient for testing complex residual current devices (RCDs) with multiple RCD circuits. Often, these complex devices include a primary circuit with its own self-contained current, requiring no external power supply, and a secondary, more complex circuit with electronic components that do require a power supply. Typically, the primary circuit detects AC or pulsed current faults, while the secondary circuit detects DC, AC, or pulsed current faults.

[0007] Conventional test circuits inject or circulate a differential fault signal or current through measuring current transformers. Processing circuits then detect the fault and trigger the opening of an electrical device such as a switch or circuit breaker. In this case, during the test, only one protection circuit needs to operate to trigger the trip. Consequently, the test is incomplete and does not reflect the overall proper functioning of all the differential protection circuits. DESCRIPTION OF THE INVENTION

[0008] The invention, as defined by the set of claims below, aims at a test method and a differential protection device having an improved test of differential protection chains.

[0009] According to the invention, a differential protection testing method having a first differential protection chain, a second differential protection chain, and a processing unit comprises: a step of controlling the circulation or injection of a test signal of the differential protection for a predetermined duration less than a non-tripping time of said first and said second differential protection chains, steps of determining a state of said first and said second differential protection chain after circulation of a test signal, of checking the conformity of the evolution of the protection chains, and of determining the state of the test, and a tripping or signaling step if the test is satisfactory.

[0010] According to the invention, said second differential protection chain requiring an electrical supply is associated with the processing unit, and the method includes during the test phase a step of inhibiting or selecting long tripping of the second differential protection chain before the control of circulation or injection of said test signal.

[0011] Preferably, during state determination steps of said first differential processing chain, the process controls a timing or filtering component of said first differential protection chain not requiring power supply.

[0012] According to the invention, the method includes a step for detecting action on a test control element to manually initiate a test cycle and / or steps for automatically and periodically initiating said test cycle. Preferably, the method includes a step for resetting a digital part of the processing unit if the test state is not satisfactory.

[0013] According to the invention, in a differential protection device comprising: a first differential protection chain, a second differential protection chain, a test device for testing said differential protection chains, and a processing unit connected to modules of the second differential protection chain to receive a signal representative of the processing of said second chain,

[0014] said processing unit: is also connected to the first differential protection chain to receive a signal representative of the differential protection and to determine the state of the protection of said first chain, includes an output to control the circulation of a test signal or current for a predetermined duration less than a non-tripping time of said first and second differential protection chains, includes modules to control the evolution of the protection chains and determines the state of the test, and controls the tripping of the opening of an electrical device or a signal if the test is good.

[0015] Advantageously, the processing unit includes modules to determine the state of said first chain and said second chain of differential protection before the flow of a test signal or current and to control the test device according to the state of the first and second chain of differential protection.

[0016] Advantageously, the first differential protection chain is a chain operating in alternating or pulsed fault current not requiring an electrical supply for its own operation.

[0017] According to the invention, the second differential protection chain operates for continuous, alternating or pulsed fault currents and is powered by an electrical supply, said processing unit being associated with said second differential protection chain for differential protection processing.

[0018] Preferably, the first differential protection chain includes a timing or filtering component, said component being connected to the processing unit to provide a signal representative of the state of the first differential protection chain.

[0019] According to the invention, the differential protection device includes a test control element connected to the processing unit to manually control a test cycle.

[0020] Advantageously, the opening of a device is triggered by a command during a circulation time of a test current greater than the tripping time of the first protection chain or the second protection chain.

[0021] Advantageously, the opening of a device is triggered by a direct control of a triggering relay by said processing unit or by an output of the processing unit controlling the charge of a capacitor also used for storing the electrical energy of control of said triggering relay.

[0022] Advantageously, in an electrical protection device comprising main contacts, a mechanism for opening said main contacts, main conductors connected in series with said main contacts and a differential protection device having at least two differential protection chains, said differential protection device is a device as defined above comprising current sensors for said differential protection chains surrounding said main conductors and providing signals representative of differential fault currents, said opening mechanism being actuated by a tripping relay in the event of detection of a differential fault or successful testing of said differential protection chains. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other advantages and features will become clearer from the following description of particular embodiments of the invention, given by way of non-limiting examples, and shown in the accompanying drawings, in which: there figure 1 represents a block diagram of an electrical appliance incorporating a differential protection device according to the prior art; the figure 2 represents a block diagram of an electrical device comprising a differential protection device according to a first embodiment of the invention; the figure 3 represents a block diagram of an electrical device comprising a differential protection device according to a second embodiment of the invention; the Figures 4A to 4D represent signal timing diagrams in a differential protection device according to embodiments of the invention; the figure 5represents a first flowchart for differential protection testing according to one embodiment of the invention; and the figure 6 represents a second differential protection test flowchart according to an embodiment of the invention. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0024] There figure 1This represents a block diagram of an electrical device 1 comprising a test device 2 for a residual current protection device according to a known embodiment. The electrical protection device comprises main contacts 3, a mechanism 4 for opening said main contacts 3, main conductors 5 connected in series with said main contacts, and a residual current protection device 6 having at least two residual current protection chains. A first residual current protection chain 7 with its own current does not require an external power supply, and a second residual current protection chain 8 requires a power supply. The first chain 7 comprises a first electronic processing module 9 connected to a first measuring sensor 10, such as a transformer or a magnetic current transformer 11.The transformer or toroid 10 provides a measurement signal or current Id1 on a secondary winding 13, representative of a differential current Id flowing in the lines of the main conductors 5. The measuring sensor 10 surrounds all the main conductors 5 and provides a measurement current Id1 for differential protection in alternating or pulsed current. The measurement current Id1 supplied by the toroid is sufficient to operate the first protection module 9 and to activate the trip relay 12. The second differential protection chain 8 requires a power supply 14. This power supply 14 is generally connected to the lines of the main conductors 5 and includes a voltage converter to power electronic processing circuits. The second chain 8 includes a second electronic processing module 15 connected to a second measuring sensor 16.The sensor 16 is generally a complex magnetic circuit sensor 17 comprising an excitation winding 18 and a measuring winding 19 providing a second measuring signal Id2. The measuring sensor 16 also surrounds all the main conductors 5 and provides a measuring current Id2 for differential protection of all types of currents, whether direct, alternating, or pulsed. The second processing circuit also activates the tripping relay 12 in the event of a differential fault.

[0025] The protection circuits are tested conventionally by generating a differential current between the upstream and downstream ends of current sensors 10 and 16. The test device 2 comprises a test current-limiting resistor 20 and a test push button 21 connected in series between a first upstream line conductor and a second downstream line conductor. When the test is initiated by pressing the push button, a fault current is generated, and the most affected or fastest processing circuit triggers the relay 12 and opens the contacts 3 via the mechanism 4. Thus, the two protection circuits are not tested during the same test.

[0026] A differential protection device according to the invention includes a test of the differential protection functions allowing at least two differential protection chains to be tested during the same test. figure 2Figure 6 represents a block diagram of a two-pole electrical device with two main lines and comprising a differential protection device according to a first embodiment of the invention. The differential protection device 6 comprises a first differential protection chain 7, a second differential protection chain 8, a test device 2 for testing the differential protection chains, and a processing unit 22 connected to the second differential protection chain 8.

[0027] In this embodiment, the processing unit is also connected to the first differential protection chain 7 to determine the protection status. Thus, the processing unit 22 has an input for receiving a signal S1, provided by a first processing module 9 and representative of the protection status of the first protection chain. A second signal S2, representative of the operation of the second chain 7, is provided to the processing unit by a second module 15. The processing unit 22 has an output providing a signal ST to control the circulation of a test signal IT for a predetermined duration T1 less than a non-tripping time TND of said first and second differential protection chains. The processing unit includes modules to monitor the evolution of the protection chains, determine the test status, and control the opening of an electrical device if the test is successful.The test circuit includes a switch 23 controlled by the test signal ST to circulate the differential fault current detected by the current sensors of the two protection chains. The device of the . figure 2 includes a test control unit 21 connected to the processing unit 22 to manually control a test cycle.

[0028] The processing unit includes modules for determining the state of the first differential protection chain 7 and the second differential protection chain 8 before the flow of an IT test signal, and for controlling the test device based on the state of the first and second differential protection chains. After or during the flow of the test current, the modules of the processing unit monitor the evolution of the two protection chains. Then, if the evolution of the two chains is compliant, they signal and / or control the opening of a device. Otherwise, a signaling output connected to an indicator 25 signals a failed test. A communication circuit 26 connected to the processing unit can also signal the operating status of the test.

[0029] Preferably, the triggering is carried out by a command during a time T4 of circulation of a test current IT greater than a triggering time TD of the first processing chain and / or the second processing chain.

[0030] Another way to control the triggering is to directly control relay 12 via an output from the processing unit. On the figure 2 The relay is controlled by a signal D directly from the first processing chain or by an output of the processing unit. In this case, the second differential protection chain is also processed by digital modules integrated into the processing unit 22.

[0031] In this embodiment, the first differential protection chain 7 is a self-current chain operating with alternating or pulsed fault currents and does not require a power supply for its operation. The second differential protection chain 8 operates with alternating or pulsed direct current faults and is powered by a power supply 14. The processing unit 22 is preferably associated with the second differential protection chain for differential protection processing. The power supply 14 provides the energy necessary to operate the second processing chain and the processing unit. It includes a reference voltage output 27 and at least one supply line voltage output V to power the circuits.

[0032] There figure 3This represents a block diagram of a four-pole, four-conductor electrical device comprising a differential protection device according to a second embodiment of the invention. The first differential protection chain 7 comprises, in module 9, a rectifier 30 connected to the secondary winding 13 of the first sensor 10, a resistor 31 connected to the output of the rectifier, and a capacitor 32 connected to the resistor 31 and the rectifier. The resistor 31 and capacitor 32 circuit provides a time delay for the tripping of the first processing chain. The capacitor is also connected to a voltage threshold comparator 33 to control a thyristor 34 or a control transistor for the tripping relay 12. The electrical energy stored in the capacitor 32 is used to control and power the tripping relay of the first processing chain without requiring an additional power supply.The measurement signal from the first sensor is sufficient to charge capacitor 32, which acts as a timer and energy reservoir. Due to its timing or filtering function, capacitor 32 has a voltage representative of the differential protection of the first circuit. Capacitor 32 is advantageously connected to the processing unit to provide signal S1, which represents the state of the first differential protection circuit. Thus, the timing or filtering component 32 is also a capacitor used for storing the electrical energy required to control the tripping relay.

[0033] The second processing chain 8 includes in its module 15 a current measurement circuit capable of measuring continuous, alternating, or pulsed differential fault currents, for example, currents with frequencies ranging from 0 Hz to several kHz. This circuit 35 sends excitation signals to a winding 18 of the second sensor and measures a current value on a second winding 19. The operating frequency of the circuit 35 is controlled by a connection 36 with the processing unit. The measurement signal from the second processing chain is filtered by a low-pass filter 37 and then supplied by signal S2 to the processing unit.

[0034] The processing unit controls the flow of a test signal or current for a non-tripping time T1 (TND). It then determines the operating status of the two processing chains and the test status. If the test is successful, a trip is triggered; otherwise, a faulty test is reported, indicating a chain that is not responding as expected. At the end of the test, a first indicator light (25A) connected to the processing unit signals a test fault, and a second indicator light (25B) signals a successful test. In a more complex system, a measurement of a prior differential fault current or the prior status of the protection chains allows the test signal generation time to be determined, which will be shorter than the tripping time. A fault prior to the test could reduce the non-tripping time.Similarly, memorizing the state of the differential protection before the test and restoring a compatible state after the test is useful if the test is used for proper functioning signaling.

[0035] The relay can be triggered by direct control of the triggering relay by the processing unit. Regarding the embodiment of the figure 3 An output D2 of the processing unit is connected to a module 38 to control the charging of the capacitor 32, which is also used for storing the electrical energy to control the triggering relay 12. The triggering is then done indirectly through the capacitor 32, the comparator 33, and the thyristor 34.

[0036] Thus, an electrical protection device according to an embodiment of the invention comprises main contacts 3, a mechanism 6 for opening said main contacts 3, main conductors connected in series with said main contacts and a differential protection device having at least two differential protection chains, as defined above.

[0037] THE Figures 4A to 4D represent signal timing diagrams in a differential protection device according to embodiments of the invention. On the figure 4A At time t1, a test signal ST is triggered for a duration T1 less than a non-triggering time TND. On the figure 4BInitial processing of the protection chain signals is performed, notably at the beginning and end of a time interval T2. For example, at time t1, the state of the protection chains is determined before or at the beginning of the test, and at time t2, the state of the protection chains is determined after the test signal by a process 40. At time t3, the analysis 41 of the test state begins for a duration T3, and at time t4, a decision is made to signal or trigger the opening of a device. Triggering can occur via the test signal by sending a test current for a duration T4 greater than the triggering time TD. The device will trigger via a protection chain after a triggering time TD at time t5, as shown in the diagram. figure 4C In another embodiment, the triggering can be done directly by a relay command, as in the figure 4D .

[0038] There figure 5This represents a first flowchart for differential protection testing according to an embodiment of the invention. The differential protection testing method has a first differential protection chain 7, a second differential protection chain 8, and a processing unit 22. At a step 50, a test phase begins. When the test is intended to be manual, the method includes a detection step 51 of the action on the test control element to initiate the test cycle. The control element is generally a push button on the front panel of a protective device or apparatus. To extend the non-tripping time, the method includes a step 52 of inhibiting or selecting the long tripping of the second differential protection chain before the control for circulation or injection of said test signal.To facilitate processing, the second differential protection chain, which requires a power supply, is connected to the processing unit for its processing functions. Then, a step 53 controls the flow of an IT current or the injection of a test signal for the differential protection for a predetermined duration T1, less than the non-tripping time TND of both the first and second differential protection chains. After the test signal has flowed, a step 54 determines the status of the first differential protection chain and verifies the conformity of its operation. If the test is unsuccessful or inconclusive on the first chain, the process directs the end of the test to an initial processing step to handle the failed test.If the check in step 54 is successful, step 55 determines the status of the second differential protection chain and verifies its operational conformity. If the test is unsuccessful or inconclusive on the second chain, the process redirects to the first end-of-test handling procedure to manage a failed test. If the check in step 55 is successful, this means that both chains are functioning correctly. The process then redirects to a second end-of-test handling procedure to manage a successful test. If the test is successful, step 56 signals the end of the test, notably with an indicator light and / or a communication, and step 57 triggers the opening of an electrical device to also test the mechanical part of the device.If the test is unsuccessful or non-compliant, step 58 signals the end of the test, notably with an indicator light and / or communication, then step 59, a reset procedure, resets a digital part of the processing unit. (See the flowchart of the...) figure 5 Steps 54 and 55 perform the two combined functions of determining the states of the residual current protection devices and the two conformity checks. However, these functions can be carried out in separate steps: one step for determining the states and one step for the conformity check for each protection chain.

[0039] There figure 6This represents a second differential protection test flowchart according to an embodiment of the invention. In this flowchart, a step 60 detects an action on a push button to initiate a manual test or a periodic automatic test. A step 61 determines the state of the first and second differential protection chains before the flow of a test signal or current. Then, a step 62 calculates the duration of the injection or flow of the test current. In this case, the duration depends on the initial state of the protection, particularly in the event of a fault current or residual leakage current. The test flow time T1 can be reduced to ensure that the device does not trip during the test. In a step 63, the test current flows for the previously calculated duration. Then, a step 64 determines the state of the two differential protection chains after the test current has flowed.Step 65 determines the conformity of the state evolution of the two differential protection chains. If the test is successful, step 66 triggers the tripping of an electrical device and / or signals a successful test. If the test is unsuccessful or non-compliant, step 67 signals a failed test.

[0040] During the test phase, particularly during steps 54, 61, or 64, of determining the first processing chain, the process controls a timing or filtering component 32 of said first differential protection chain not requiring power supply.

[0041] The differential protection tests described above also apply to differential protection devices with more than two protection chains. The two chains are not a limitation but rather an illustration of preferred embodiments.

[0042] The embodiments described above demonstrate that the test is triggered by manually pressing a push button. This action is primarily used to trigger the opening of an electrical device. However, the test can also be triggered periodically and automatically. In this case, local or remote signaling is preferred.

[0043] In the embodiments described above, the test is performed by generating a differential fault current by diverting a current between the upstream and downstream sides of the current sensors. However, other types of test signal generation are possible, including the use of additional test windings in differential current sensors and / or with generators powered and controlled by the processing unit.

[0044] The electrical device shown on the figure 1is a bipolar device with two lines, phase and neutral. However, the invention also applies to bipolar, tripolar, or tetrapolar devices.

Claims

1. Method for testing differential protection having a first differential protection chain (7), a second differential protection chain (8), and a processing unit (22), the method comprising: - a step (53, 63) of commanding the circulation or injection of a test signal of the differential protection for a predetermined duration (T1) less than a non-tripping time (TND) of said first and of said second differential protection chains (7, 8), - steps (54, 55, 64, 65) of determining a state of said first and of said second differential protection chain after circulation of a test signal, of checking the conformity of the evolution of the protection chains, and of determining the state of the test, and - a step (57, 59, 65, 67) of tripping or of signaling if the test is satisfactory, the method being characterized in that said second differential protection chain requiring an electrical power supply is associated with the processing unit, in that it comprises during the test phase a step (52) of inhibiting or of selecting long tripping of the second differential protection chain before the command for circulation or injection of said test signal, and in that it comprises a step (51, 60) of holding the action on a test control member to manually launch a test cycle and / or steps for automatically launching periodically said test cycle.

2. Test method according to claim 1 characterized in that during steps of determining the state of said first differential processing chain, the method controls a timing or filtering component (32) of said first differential protection chain (7) not requiring an electrical power supply.

3. Test method according to any one of claims 1 or 2 characterized in that it comprises a step (59) of resetting a digital part of the processing unit if the state of the test is not compliant.

4. Differential protection device (6) comprising: - a first differential protection chain (7), - a second differential protection chain (8), - a test device (2) for testing said differential protection chains, and - a processing unit (22) connected to modules of the second differential protection chain (8) to receive a signal (S2) representative of the processing of the said second chain, where said processing unit (22): - is also connected to the first differential protection chain (7) to receive a signal (S1) representative of the differential protection and to determine the state of the protection of said first chain, - comprises an output (ST) for commanding the circulation of a signal or of a test current (IT) for testing for a predetermined duration (T1) less than a non-tripping time (TND) of said first and of said second differential protection chains (7, 8), - comprises modules (22, 54, 55, 64, 65) for checking the evolution of the protection chains and determining the state of the test, and - commands the tripping (D) of the opening of an electrical apparatus or a signaling if the test is good, the device being characterized in that the second differential protection chain (8) operates for direct, alternating or pulsed fault currents and is powered by an electrical power supply (14), said processing unit (22) being associated with said second differential protection chain (8) for the processing of the differential protection, and in that it is configured to, during a test phase implement a step (52) of inhibiting or of selecting long tripping of the second differential protection chain before the command for circulation or injection of said test signal, and in that it comprises a test control member (21) connected to the processing unit (22) to manually command a test cycle and / or steps for automatically launching periodically said test cycle.

5. Differential protection device according to claim 4 characterized in that the first differential protection chain (7) is a chain operating with alternating or pulsed fault current not requiring an electrical power supply for its own operation.

6. Differential protection device according to any one of claims 4 or 5 characterized in that the first differential protection chain (7) comprises a timing or filtering component (32), said component (32) being connected to the processing unit (22) to provide a signal (S1) representative of the state of the first differential protection chain (7).

7. Test device according to any one of claims 4 to 6 characterized in that a tripping of the opening of an apparatus is carried out by a command (ST) for a time (T4) of circulation of a test current (IT) greater than a tripping time (TD) of the first protection chain (7) or of the second protection chain (8).

8. Test device according to any one of claims 4 to 7 characterized in that a tripping of the opening of an apparatus is carried out by a direct command (D) of a tripping relay (12) by said processing unit or by an output (D2) of the processing unit commanding the charge of a capacitor (32) also used for a storage of the electrical energy for commanding said tripping relay (12).

9. Electrical protection apparatus comprising main contacts (3), a mechanism (6) for opening said main contacts (3), conductors main connected in series with said main contacts and a differential protection device having at least two differential protection chains, characterized in that said differential protection device is a device according to one of claims 4 to 8 comprising current sensors (10, 16) for said differential protection chains (7, 8) surrounding said main conductors (3) and providing signals representative of differential fault currents, said opening mechanism (6) being actuated by a tripping relay (12) in the event of detention of differential fault or of conclusive test of said differential protection chains.