JP2004354378A - Insulation inspection device and inspection method of electrical insulation section - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve existing insulation inspection devices and methods, to enable reliable inspection using a simple structure. <P>SOLUTION: It is an insulated inspection device for inspecting an object 12 to be examined, with which an electrical insulation section 10 is arranged between a first conductive material and a second conductive material separated electrically. The insulated inspection device of a configuration is provided with an electrical circuit which has the first contact point and the second contact point that can contact respectively the conductive materials of an object to be examined, and an evaluation device corresponding to the electrical circuit are improved, so that the contact inspection device 29 is formed, in order to make it possible to execute reliable insulated inspection. By means of this contact inspection device 29, inspection current flow on each contact of electrical circuits can be made. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an insulation inspection apparatus for an inspection object in which an electric insulation portion is disposed between a first conductive member and an electrically separated second conductive member. And an evaluation circuit for the electric circuit having a first contact and a second contact which can be respectively contacted with the conductive member.

  Further, the present invention relates to a method for inspecting an electrical insulation portion of an inspection object in which an electrical insulation portion is disposed between a first conductive member and an electrically separated second conductive member. Further, the present invention relates to a configuration in which a first contact is connected to a first conductive member, a second contact is connected to a second conductive member, and a voltage is applied for performing an insulation test.

  Such an insulation inspection apparatus and an application example of such an inspection method are described in, for example, the insulation between a stator winding (corresponding to a first member) and a rotor winding (corresponding to a second member) in an electric motor. Checking of parts or checking of insulation between stator winding / rotor winding and stator housing.

  To test the insulation, the insulation resistance must be measured or detected as to whether the insulation resistance is above a predetermined threshold. To this end, a voltage is usually applied and the current is measured. If the current is below the threshold or if the current cannot be measured, the electrical insulation is determined to be good.

  An object of the present invention is to improve the insulation test device described at the outset and the test method described at the outset to enable a reliable check with a simple structure.

  According to the present invention, in the insulation inspection device described at the beginning, a contact inspection device is provided, and the contact inspection device can apply an inspection current to each contact of an electric circuit, thereby solving the above problem. Is resolved.

  In principle, the problem is that the current value below the threshold value or the unmeasurable current value detected during the voltage measurement may have various causes. In addition to high insulation resistance (corresponding to good insulation), faulty or faulty contact with the test object can also lead to low or unmeasurable current values. Further, disconnection of the wiring of the electric circuit may also lead to an unmeasurable current value. Contact failures may be due, for example, to contact oxidation and / or mechanical wear. If such a problem occurs, for example, a defective component having a defective insulating portion may be determined to be good due to a defective contact.

  In the present invention, a contact inspection device is provided, and the inspection current can be applied to each contact of the electric circuit by the contact inspection device. Appropriate measurement is performed particularly when there is no voltage at each contact provided on the first conductive member and the second conductive member sandwiching the electrical insulating part constituting the inspection object, or It is performed at a voltage that is significantly lower than the voltage for the insulation test (the voltage for the insulation test must be high enough to determine the strength of the dielectric breakdown resistance with sufficient accuracy). Can be). In this way, it is possible to check whether or not current is flowing through each contact. If an energization above the threshold occurs, the contact is good and there is no fault in the corresponding supply wiring leading to the contact. On the other hand, if the inspection current is below the threshold, the cause can be attributed to a contact failure or a corresponding wiring failure.

  Using the insulation inspection device according to the present invention, before and / or after the original insulation inspection, it is possible to determine whether there is good electrical contact between the contact of the (high voltage) electric circuit and the inspection object. it can. This contact inspection itself can be performed without having to remove each contact from the inspection object. A current value can be obtained by appropriately closing the electric circuit so that a current can flow through the conductive member and the evaluation can be performed.

  The contact inspection device according to the present invention can be embodied by a simple circuit technology. Since it is not necessary to isolate the electrical circuit with respect to the contact of the test object, the contact can be checked, so to speak, "on the fly".

  The contact inspection device preferably has at least one first inspection contact and a second inspection contact. At this time, the test contact can be coupled to the conductive member of the test object. The current can then flow through the conductive member to each contact of the electrical circuit, and thus the quality of the contact can be checked.

  In this case, the test contact may be or may be intended to be coupled to the electrical wiring of a (high-voltage) electrical circuit. This connection is particularly performed in addition to the connection of the test object to the conductive member. In such an embodiment, the test current can be communicated via electrical wiring, and thus the test current acts on each contact of the electrical circuit.

  It is highly preferred that the contact inspection device includes a low voltage electrical circuit, in which the voltage is significantly lower than the voltage for the insulation inspection. In low-voltage electrical circuits, correspondingly small currents flow. This can be realized in a circuit-technically simple manner. Accordingly, it is possible to reduce the oxidation of the inspection contact for bringing the respective contact inspection devices of the inspection object into contact.

  In particular, the contact inspection device has a voltage source that is an energy source for the inspection current. This voltage source is preferably a low voltage source.

  Furthermore, it is advantageous if the contact inspection device can be decoupled or decoupled from the electrical circuit with respect to voltage, in particular high voltage. As a result, a high-pressure action on the contact inspection device is prevented, so that the contact inspection device can be embodied by a simple circuit technology.

  In one embodiment, one or more switches are provided for decoupling. When the switch is in a particular switching position (eg, open), the contact inspection device is uncoupled. The switch is moved to this position when the insulation test is in the energized state. Such a transition to the corresponding position is preferably made automatically and provided with a suitable relay.

  In particular, one or more switches are located in the test electronics. This makes it possible, for example, to decouple the evaluation device arranged in the test electrical circuit in a simple manner.

  One or more switches may be intended to be arranged in the (high voltage) electrical circuit. This makes it possible to bridge the voltage supply to the (high-voltage) electrical circuit at the corresponding switching position when performing the contact inspection measurement.

  One or more rectifying members, for example, a diode or the like arranged in the test current circuit may be provided. Thereby, if the rectifying member is appropriately arranged and configured, the connection is automatically released. This can be done in a particularly simple way if the insulation test is carried out via a DC high voltage.

  Advantageously, the contact inspection device has an evaluation device for the inspection current. Then, by determining the value of the inspection current, it can be determined whether or not there is a problem with the contact. In particular, if the inspection current is below the threshold, it is estimated that there is a problem with the contact.

  The voltage applied for the insulation test is high, particularly in the sense that it is sufficient to determine the strength of the dielectric breakdown resistance with the required accuracy. Typically, this voltage is higher, in particular much higher, than the operating voltage of the test object.

  It is advantageous if no high voltage is applied during the contact test measurement of the (high-voltage) electrical circuit, ie the voltage supply of the high-voltage electrical circuit is disconnected.

  In one embodiment, the contact inspection device includes an inspection electric circuit for coupling the inspection object to the conductive member. Then, an inspection current is communicated through the conductive member, and the inspection current flows to an adjacent contact of the electric circuit through the conductive member.

  The contact inspection device may include an inspection electrical circuit that can or is coupled to the wiring of the (high voltage) electrical circuit. Thereby, a current acts on the contact via this wiring. If the contact is good, this current will flow through the conductive member of the test object.

  In that case, if the contact inspection device includes a bridge device for electrically connecting the respective conductive members of the inspection object, the electric circuit can be closed. Thus, the inspection current is communicated through the contact, so that when a short-circuit current occurs in the inspection object, it is possible to prevent the short-circuit current from affecting the contact inspection measurement.

  Preferably, the conductive connection between each conductive member of the test object can be opened and closed. Thereby, the electrical connection can be opened before performing the (high pressure) measurement for the insulation test.

  Further, according to the present invention, in a method belonging to the field, in order to perform a contact inspection, a contact between a first conductive member and a second conductive member sandwiching an electrical insulating portion constituting an inspection object is provided. The above-mentioned problem is solved by applying the test current to each contact in a state where there is no voltage or a state where the voltage is low.

  The method according to the invention has the advantages already described in connection with the device according to the invention.

  Other advantageous embodiments of the method according to the invention are likewise already described in connection with the device according to the invention.

  The test electrical circuit is advantageously closed via both conductive members.

  If the contact is good, the test current preferably flows through each contact of the (high voltage) electrical circuit, i.e., if the test current is detected above a certain threshold, each contact is good. You can judge.

  In particular, the test current flows through the conductive member of the test object.

  In this case, it may be provided that the test current is communicated via the conductive member and acts on each contact. Such a circuit can be implemented in a simple way.

  The inspection current can be communicated via a wiring for applying a voltage (high voltage). Thereby, only if each contact is good enough, since the test current must flow through each contact before it can flow through the conductive member of the test object. It can be realized that the test current flows through the test electrical circuit.

  The following description of the preferred embodiments is for describing the invention in detail with reference to the drawings.

  As shown schematically in FIG. 1, an insulation inspection apparatus according to the present invention includes an inspection object 12 having an electrical insulation portion 10 disposed between a first conductive member 14 and a second conductive member 16. This serves to inspect the electrical insulation part 10 of the first embodiment. The two conductive members 14 and 16 are electrically separated from each other. This is, for example, the stator winding and the rotor winding of an electric motor, each electrically separated by an insulating layer.

  In order to perform an insulation test, a measuring device 18 including an electric circuit 20, hereinafter referred to as a high-voltage electric circuit 20, is usually provided. The high voltage here means a voltage high enough to perform an insulation test with required accuracy. In particular, this voltage is significantly higher than the typical operating voltage of the test object 12, for example an electric motor. The high voltage electrical circuit 20 is coupled to a first contact 22 and a second contact 24, both contacts 22 and 24 being preferably configured as contact tips. A voltage of, for example, 250 V or more is applied to the conductive members 14 and 16 via the high-voltage electric circuit 20, and the insulation resistance of the inspection object 12 can be obtained through the current of the high-voltage electric circuit 20. A suitable voltage supply 26 supplies the high voltage. The evaluation device 28 evaluates the measurement result.

  For example, when a constant voltage is applied and a current below a predetermined threshold is detected, or when a measurable current is not detected, the electrical insulating unit 10 is determined to be good. Conversely, when the current exceeds the threshold value, it is determined that the electrical insulation unit 10 is not sufficient, and the test object 12 is discarded.

  However, the low or unmeasurable current through the high-voltage electrical circuit 20 is not caused solely by the good electrical insulation 10 and the measurement wiring of the high-voltage electrical circuit 20 is broken or the test object 12 It is also caused by poor contact of the measuring device 18 with the device.

  For example, in a contact chip including the contacts 22 and 24, a problem that the chip is oxidized by a current often occurs as a real problem. Further, there is a possibility that mechanical abrasion may occur due to the crimping to the inspection object 12.

  When such a problem (breakage of the measurement wiring, poor contact, no contact) occurs, the measuring device 18 gives a measurement result of “current below the threshold”, which may be attributed to the good insulating portion 10. Rather, it can be attributed to the failure of the coupling of the measuring device 18 to the inspection object 12.

  Therefore, in the present invention, a contact inspection device is provided, and the wiring of the high voltage electric circuit 20 is not required to be disconnected with respect to the connection to the respective contacts 22 and 24 by the contact inspection device. The contact of the measuring device 18 with the inspection object can be monitored.

  In a first embodiment of such a contact inspection device, generally designated 29 in FIG. 1, is coupled to the first conductive member 14 via a first inspection contact 32 and a second A test electrical circuit 30 is provided that is coupled to the second conductive member 16 via a test contact 34.

  A voltage source 36 is arranged in the test electric circuit 30. The test electric circuit 30 here is preferably a low-voltage test electric circuit. The voltage of the low-voltage test electronics 30 is significantly lower than the voltage of the high-voltage electronics 20 and is typically in the range of 6V to 24V.

  The inspection electric circuit 30 includes an evaluation device 38, and the current value can be obtained by the evaluation device.

  A first switch 42 is arranged on the wiring 40 of the test electrical circuit 30 that leads from the voltage source 36 to the first test contact 32. When the first switch 42 is closed, the first test contact 32 is coupled to the voltage source 36. When the first switch is open, the electrical wiring is interrupted.

  Similarly, a second switch 46 is disposed on a wiring 44 leading from the voltage source 36 to the second inspection contact 34. When the switch is closed, the second inspection contact 34 and the voltage source 36 are interconnected, while when the switch 46 is open, the electric wiring is cut off.

  When the switches 42, 46 are open, the test circuit 30 is decoupled from the high voltage circuit 20.

  In principle, it is sufficient to provide only one switch instead of the two switches 42, 46.

  The high-voltage electric circuit 20 is provided with a bridging wiring 48, and the bridging wiring allows both contacts 22, 24 to have the same potential. For this purpose, a switch 50 is arranged on the bridging wiring 48. When the switch 50 is closed, both contacts 22, 24 are connected together and at the same potential. When the switch 50 is open, the corresponding wiring of the measuring device 18 is connected to the voltage supply device 26, so that it is possible to apply a voltage to both contacts 22, 24.

  The switches 42, 46, 50 are preferably interconnected so that they can be closed together or open together.

  In order to inspect the contacts 22 and 24 through the contact inspection device 29, in the present invention, the procedure proceeds as follows.

  The voltage supply 26 is decoupled, i.e. no high voltage is applied to the contacts 22,24. Switches 42, 46 and 50 are closed. A current is generated in the test electrical circuit 30 so that the first contact 22 is on the first conductive member 14 of the test object 12 and the second contact 24 is on the second conductive member of the test object 12. The test circuit is closed by the high-voltage circuit 20 provided with the bridging line 48, provided that each is in good electrical contact with the member 16 and the wiring 52 of the high-voltage circuit 20 is not broken. Then, current flows between the test contact 32 and the first contact 22 through the first conductive member 14, and passes through the high-voltage electric circuit 20 including the bridging wiring 48 to the second contact 24. To the second test contact 34 via the second conductive member 16. The current value can be detected through the evaluation device 38.

  If this current value exceeds the threshold value, this means that the high-voltage electric circuit 20 is in good contact with the inspection object 12 and the wiring 52 is not disconnected (however, FIG. See also the following description relating to

  In this case, the switches 42, 46 and 50 are subsequently opened and a known high-pressure measurement is performed on the test object 12. If a current value below the threshold is recorded, it can be attributed to good electrical insulation. Since the check is performed in advance through the contact inspection device 29, it is possible to eliminate the possibility that the inspection object 12 has a poor contact through the contacts 22 and 24 or that the wiring 52 is disconnected.

  On the other hand, when a current value lower than the threshold value is detected by the evaluation device of the contact inspection device 29, this indicates that there is a problem with the contact to the inspection object 12 by the contacts 22, 24, or that the wiring 52 It means there is a problem. In that case, there is no point in performing high-pressure measurement on the inspection object 12. First, you must find out why the current is too low and eliminate the problem.

  The method according to the present invention eliminates the possibility that a faulty component having a faulty electrical insulation 10, i.e., the test object 12, is incorrectly determined to be good due to a faulty contact. You. The inspection current flows only when the contacts 22 and 24 are electrically connected to the conductive members 14 and 16. It is not necessary to release the mechanical contact between the conductive members 14 and 16 and the contacts 22 and 24.

  The method according to the invention works irrespective of whether the high-voltage measurement is performed with a DC voltage or with an AC voltage.

  The switches 42, 46 allow the evaluation device 38 to be disconnected from the high-voltage electrical circuit 20. This ensures that no high pressure acts on the evaluation device.

  In this embodiment, the test current is communicated to the conductive members 14, 16 via test contacts 32, 34 and flows therefrom to the contacts 22, 24.

  The voltage source 36 is selected such that a sufficiently large test current flows through the test electronics 30. This voltage is adapted to the measuring device 18 with the bridging section via the bridging line 48 (when the switch 50 is closed). This voltage is preferably chosen such that the voltage supply 26 and the evaluation device 28 are not affected.

  In the second embodiment of the insulation inspection apparatus according to the present invention, which is denoted by reference numeral 54 in FIG. 2 as a whole, a DC voltage supply device 56 is provided. Further, an evaluation device 58 corresponding to the evaluation device 28 is provided. The measuring device coupled to the DC voltage supply 56 corresponds to the measuring device described in FIG. Therefore, the same components as those in FIG. 1 are denoted by the same reference numerals.

  Similarly, a contact inspection device 60 including an inspection electric circuit 62 is provided. The test electrical circuit is likewise coupled to the test object 12 via the test contacts 64, 66, ie to the conductive members 14, 16. The test electrical circuit 62 is likewise provided with an evaluation device 68. A voltage source 70 which is a DC voltage source is arranged in the test electric circuit 62.

  Instead of the switches 42, 46, a rectifier 72, for example in the form of a diode, is provided for decoupling the test circuit 62 from the high-voltage circuit 20. The rectifier 72 is arranged and configured such that when the switch 50 of the bridging wiring 48 is closed, current can flow through the test electrical circuit 62 (poor contact or defective wiring 52). Is missing).

  However, the rectifier 72 is arranged with respect to the DC voltage supply device 56 so that when a high voltage of the corresponding polarity is applied to the contacts 22 and 24, no current can flow through the test electric circuit 62.

  When performing a high voltage measurement on the test object 12, the test electrical circuit 62 and the associated contact inspection device 60 can be automatically decoupled from the high voltage electrical circuit 20 via the rectifier 72.

  In the third embodiment of the insulation inspection apparatus according to the present invention, which is schematically shown in FIG. 3 and generally denoted by reference numeral 74 in the same figure, similarly, a high-voltage voltage supply device 76 and an evaluation device 77 are provided. In order to form a high-voltage electrical circuit 79, a wiring 78 has a first voltage output portion 80 of the voltage supply device 76 and a first contact for making contact with the first conductive member 14 of the test object 12. 82 is connected. The second wiring 84 connects the second voltage output unit 86 of the voltage supply device 76 to the second contact 88 for making contact with the second conductive member 16 of the inspection object 12.

  The contact inspection apparatus 90 according to the present invention includes an inspection electric circuit 92 coupled to the wires 78 and 84 and connectable to the contacts 82 and 88 via the wires 78 and 84. In this case, the inspection current is communicated to the wirings 78 and 84.

  The test electric circuit 92 includes a voltage source 94 and an evaluation device 96. Furthermore, switches 98 and 100 are provided, by means of which the evaluation device 96 can be decoupled from the wiring 78 and the wiring 84, respectively.

  In order to close the test electrical circuit 92, the test object 12 is coupled to the first conductive member 14 of the test object 12 via the first test contact 104, and the test object 12 is closed via the second test contact 106. A bridging device 102 is provided that is coupled to the second conductive member 16. A wiring 108 connects both test contacts 104 and 106, and a switch 110 is arranged on the wiring 108. When switch 110 is closed, both test contacts 104, 106 are interconnected at the same potential, whereas when switch 110 is open, this electrical connection is disconnected.

  Switches 98 and 100 are closed with the high voltage turned off to make contact inspection measurements. Then, a current flows through the first conductive member 14 via the contact 82, passes through the wiring 108, passes through the second conductive member 16, and passes through the contact 88 while the switch 110 is closed. When flowing through 84, the test current can flow to test current circuit 92. The evaluation device 96 detects the current value.

  As described above, a current value below the threshold value or an unmeasurable current indicates a problem with the contact or a problem with the wiring.

  In principle, when there is a defect in the insulating unit 10, there is a possibility that a current flows due to the short-circuit of the inspection object 12 despite the poor contact. This can be clearly seen in the circuit of FIG. When the test object 12 is short-circuited, a current flows between the test contacts 32 and 34 regardless of whether or not the contact via the contacts 22 and 24 is defective. This is attributable to the fact that in the circuit of FIG. 1, the test current is directly communicated through the conductive members 14 and 16.

  With the device according to the invention shown in FIG. 3, it can also be determined whether a short-circuit current is flowing. This is because the test current is communicated via the wires 78 and 84 and must pass through the contacts via the contacts 82 and 88 before flowing through the conductive members 14 and 16.

  As described above, if there is a bad contact, or if the wiring 78 or 84 is broken, no current flows through the conductive members 14 and 16, so that a short-circuit current Is no longer a problem.

  Otherwise, the device 74 according to the invention has the same advantages as described above.

It is a schematic diagram showing a first embodiment of an insulation inspection device according to the present invention. It is a schematic diagram showing a second embodiment of the insulation inspection device according to the present invention. It is a schematic diagram showing a third embodiment of the insulation inspection device according to the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Electrical insulating part 12 Inspection object 14 First conductive member 16 Second conductive member 18 Measurement device 20 High voltage electric circuit 22 First contact 24 Second contact 26 Voltage supply device 28 Evaluation device 29 Contact inspection device (First Embodiment)
Reference Signs List 30 inspection electric circuit 32 first inspection contact 34 second inspection contact 36 voltage source 38 evaluation device 40 wiring 42 first switch 44 wiring 46 second switch 48 bridging wiring 50 switch 52 wiring 54 insulation testing device (FIG. 2)
56 DC voltage supply device 58 Evaluation device 60 Contact inspection device 62 Inspection electric circuit 64 Inspection contact 66 Inspection contact 68 Evaluation device 70 Voltage source 72 Rectifier 74 Insulation inspection device (FIG. 3)
76 voltage supply device 77 evaluation device 78 wiring 79 high voltage electric circuit 80 first voltage output part 82 first contact 84 wiring 86 second voltage output part 88 second contact 90 contact inspection device 92 inspection electric circuit 94 voltage source 96 evaluation device 98 switch 100 switch 102 bridging device 104 first test contact 106 second test contact 108 wiring 110 switch

Claims (25)

Insulation inspection for an inspection object (12) in which an electric insulation part (10) is arranged between a first conductive member (14) and an electrically separated second conductive member (16). An apparatus comprising: a first contact (22; 82) and a second contact (24; 88), each of which is capable of contacting the conductive member (14, 16) of the inspection object (12). A circuit (20; 79) and an evaluation device (28; 58; 77) for the electric circuit (20; 79);
A contact inspection device (29; 60; 74) is provided, and the contact inspection device applies an inspection current to each of the contacts (22, 24; 82, 88) of the electric circuit (20; 79). An insulation inspection apparatus characterized in that it is possible.   The contact inspection device (29; 60; 74) has a first inspection contact (32; 64; 104) and a second inspection contact (34; 66; 106). Item 2. An insulation inspection device according to item 1.   The test contact (32, 34; 64, 66; 104, 106) can be coupled to the conductive member (14, 16) of the test object (12). Insulation inspection equipment.   The insulation inspection device according to claim 2 or 3, wherein the inspection contact is connectable or coupled to an electric wiring (78, 84) of the electric circuit (79).   The insulation inspection device according to any of the preceding claims, wherein the contact inspection device (29; 60; 74) includes a low-voltage electrical circuit (30; 62; 92).   The insulation inspection device according to any one of claims 1 to 5, wherein the contact inspection device (29; 60; 74) has a voltage source (36; 70; 94).   7. The contact inspection device (29; 60; 74) is decoupleable or decoupled from the electrical circuit (20; 79) with respect to voltage. Insulation inspection equipment.   8. The insulation inspection apparatus according to claim 7, wherein one or more switches (50, 42, 46; 98, 100, 110) are provided for decoupling.   9. The insulation test device according to claim 8, wherein one or more switches (42, 46; 98, 100) are arranged in the test electric circuit (30; 92).   10. The insulation inspection device according to claim 8, wherein one or a plurality of switches (50, 110) are arranged in the electric circuit (20, 108).   The insulation inspection device according to any one of claims 7 to 10, wherein one or more rectifier members (72) are provided.   The insulation test according to any one of claims 1 to 11, wherein the contact inspection device (29; 60; 74) has an evaluation device (38; 68; 96) for an inspection current. apparatus.   13. The insulation inspection device according to claim 1, wherein the electric circuit (20; 79) is a high-voltage electric circuit.   14. The insulation inspection device according to claim 13, wherein a high voltage does not act on the electric circuit (20; 79) during a contact inspection measurement.   The contact inspection device (29; 60) has an inspection electric circuit (30; 62) for coupling to the conductive member (14, 16) of the inspection object (12). The insulation inspection apparatus according to any one of claims 1 to 14, wherein:   The contact inspection device (74) includes an inspection electrical circuit (92) that is coupleable or coupled to wiring (78, 84) of the electrical circuit (79). The insulation inspection device according to any one of the above.   The contact inspection device (74) includes a bridging device (102) for conductively connecting the conductive members (14, 16) of the inspection object (12). The insulation inspection device according to 1.   17. The insulation inspection apparatus according to claim 16, wherein a conductive connection between each of the conductive members (14, 16) of the inspection object (12) can be opened and closed.   A method for inspecting an electrical insulation portion of an inspection object, wherein an electrical insulation portion is disposed between a first conductive member and a second electrically conductive member that is electrically separated. A first contact is connected to the first conductive member, a second contact is connected to the second conductive member, and a voltage is applied. A test current is applied to each contact in a state where there is no voltage or a low voltage between the first conductive member and the second conductive member.   20. The method of claim 19, wherein a test electrical circuit is closed via the conductive member.   21. The method according to claim 19, wherein the test current flows through each of the contacts when the contact between the contacts and the conductive member is good.   The method according to claim 20, wherein the test current flows through the conductive member.   The method according to any one of claims 19 to 21, wherein the test current is communicated through the conductive member.   23. The method according to claim 19, wherein the test current is communicated via a wiring for applying a voltage.   The method according to any one of claims 19 to 24, wherein a high voltage is applied for an insulation test.

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