Insulation inspection method and insulation inspection device

Abstract

To provide an insulation inspection method and an insulation inspection device that can reduce a time required for an insulation test for a coil.SOLUTION: An insulation inspection method according to an embodiment is to determine the quality of insulation of a coil that is formed by winding a conductor line provided with an insulating coating on its surface, and includes: a switching step (S4) of switching a path to apply voltage to the coil; a charging step (S17) of charging the voltage to be applied to the coil; an application step (S14) of applying the charged voltage to the coil; and a determination step (S19) of comparing a measured waveform created on the basis of an attenuation mode of electrical energy generated with partial discharge of the coil with a reference waveform prepared in advance to determine the quality of insulation. The switching step is executed at the completion of the application step. The charging step is executed in parallel with the switching step. The determination step is executed in parallel with at least one of the switching step and the charging step.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an insulation inspection method and an insulation inspection device for determining whether the insulation of a coil is good or bad. [Background technology]

[0002] A coil is formed by winding a conductor wire with an insulating coating on its surface, and if the insulation resistance decreases due to damage to the insulating coating or other reasons, there is a risk of a so-called layer short circuit occurring. For this reason, as described in Patent Document 1, for example, a conventional insulation test is performed in which a voltage is applied to the coil, the amount of discharge charge due to partial discharge occurring between the conductor wires is measured, and the measurement data is compared with pre-prepared reference data to determine the quality of the insulation. A layer short circuit is also sometimes called a layer short circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5926940 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional methods make it difficult to reduce the time required for insulation testing, and in order to prevent insulation testing from becoming a bottleneck in the mass production process, multiple insulation testing facilities must be installed, which increases costs. For this reason, there is a strong demand in actual manufacturing sites to reduce the time required for insulation testing.

[0005] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide an insulation inspection method and an insulation inspection device that can shorten the time required for coil insulation testing. [Means for solving the problem]

[0006] The insulation inspection method according to the embodiment is for determining whether the insulation of a coil (6) formed by winding a conductor wire (5) having an insulating coating (4) on its surface is good or bad, and includes a switching step (S4) for switching the path for applying a voltage to the coil, a charging step (S17) for charging the voltage to be applied to the coil, an application step (S14) for applying the charged voltage to the coil, and a determination step (S19) for determining whether the insulation is good or bad by comparing measured waveforms (G1, G2) generated based on the attenuation pattern of electrical energy generated due to partial discharge in the coil with pre-prepared reference waveforms (G10, G20), in which the switching step is performed when the application step is completed, the charging step is performed in parallel with the switching step, and the determination step is performed in parallel with at least one of the switching step and the charging step.

[0007] The insulation inspection device (1) according to the embodiment judges the quality of the insulation of a coil (6) formed by winding a conductor wire (5) having an insulating coating (4) on its surface, and includes a control unit (21) that outputs a command to start measurement and controls switching of the path for applying voltage to the coil, a power supply control unit (31) that applies voltage based on a command from the control unit, a measurement unit (33) that measures the electrical energy generated due to partial discharge in the coil, and a judgment unit (33) that judges the quality of the insulation by comparing a measured waveform generated based on the attenuation pattern of the electrical energy with a pre-prepared reference waveform, where the control unit switches the path for applying the voltage when the application of the voltage is completed, the power supply control unit starts charging for the next measurement in parallel with the control unit switching the path, and the judgment unit judges the quality of the insulation in parallel with the charging by the power supply control unit. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an insulation test apparatus according to a first embodiment. [Figure 2] FIG. 1 is a diagram showing an example of a coil configuration and a path for applying a voltage; [Figure 3] A diagram illustrating an example of determining whether insulation is good or bad. [Figure 4]FIG. 1 is a comparative example showing the flow of steps in an insulation test using a conventional method. [Figure 5] PLC processing flow diagram [Figure 6] Diagram showing the process flow of the measuring device [Figure 7] FIG. 1 is an embodiment showing a flow of steps in an insulation test using an insulation test device. [Figure 8] FIG. 10 is a diagram showing an example of the time required for an insulation test in a comparative example and in an example; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment will be described with reference to the drawings. As shown in Fig. 1, an insulation test apparatus 1 includes a PLC 2 and a measuring instrument 3. As shown in Fig. 2, this insulation test apparatus 1 applies a voltage to a coil 6 formed by winding a conductor wire 5 having an insulating coating 4 such as enamel on its surface, and measures the electrical energy generated by partial discharges that occur between the conductor wires 5 to determine whether the insulation is good or bad. This is because if so-called pinholes 4a are generated due to contact or the like when forming the coil 6, gaps without the insulating coating 4 will be formed between the conductor wires 5, resulting in incomplete insulation.

[0010] Hereinafter, a test for determining whether the insulation is good or bad will be referred to as an insulation test. In this embodiment, it is assumed that an insulation test of the coil 6 is performed in the manufacturing process of an armature 7 for a brushed motor using the insulation test device 1. The armature 7 is also sometimes called an armature or an armature.

[0011] 1, the PLC 2 includes a control unit 21 configured by, for example, a microcomputer, and an input / output unit 22 configured by a communication circuit and an input / output circuit for contact signals (not shown). By executing a program in the control unit 21, the PLC 2 controls external devices via the input / output unit 22 so that they operate in a predetermined order.

[0012] In this embodiment, the PLC 2 controls the switch 8 and the timing of applying a voltage from the measuring instrument 3, which will be described later. At this time, when preparations such as the work of connecting the armature 7 and the switch 8 are completed, a start instruction is input to the PLC 2 from an operator or a higher-level computer, and the PLC 2 commands the measuring instrument 3 to start an insulation test in response to the start instruction.

[0013] The measuring instrument 3 includes a power supply control unit 31, a memory unit 32, a measuring unit 33, a determining unit 34, a power supply unit 35, a detector 36, and a display unit 37. The power supply control unit 31 applies the voltage charged in the capacitor 35b from the DC power supply 35a in the power supply unit 35 to the coil 6 of the armature 7 by switching the switch 35c based on a command from the PLC 2. In addition, the power supply control unit 31 notifies the PLC 2 that charging of the capacitor 35b has been completed, as will be described later. In other words, the measuring instrument 3 is configured to be able to perform a so-called impulse test.

[0014] 2, for example, three coils 6 are connected to the armature 7 in a so-called star connection. Here, if the common connection point of each coil 6 is designated as P0 and the ends of each coil 6 on the opposite side of the common connection point are designated as P1, P2, and P3, respectively, then in the insulation test, the switches 8 and each connection point are connected by test cables 9.

[0015] The path to which the voltage is applied is switched by a switch 8, for example, between P0 and P1, between P0 and P2, between P0 and P3, between P1 and P2, between P1 and P3, and between P2 and P3. Hereinafter, the path to which the voltage is applied will be referred to as the application path. In this way, a plurality of inspection points are set on one armature 7. Note that the number of coils 6, the wiring configuration, and the positions and number of connection points shown in FIG. 2 are merely examples and are not limited to these. For example, as will be described later, one armature 7 may have 18 or 32 inspection points set thereon.

[0016] The measuring unit 33 acquires the voltage detected by the detector 36 and stores it in the memory unit 32 as a measured waveform as shown in Fig. 3. That is, the measuring unit 33 converts a large number of sampled voltage values ​​in a short period of time after the voltage is applied into a measured waveform plotted in time series so that the manner in which electrical energy decays due to partial discharge can be understood.

[0017] In this embodiment, voltage is detected as electrical energy, but if the detected voltage is V, the amount of discharged charge is q, and the capacitance of capacitor 35b is C, the amount of discharged charge can also be calculated from the relationship q=CV. Therefore, the insulation test device 1 determines whether the insulation is good or bad indirectly based on the amount of discharged charge. Alternatively, the insulation test device 1 may be configured to detect the current flowing in the application path as electrical energy and determine whether the insulation is good or bad.

[0018] The judgment unit 34 judges whether the insulation is good or bad by comparing the measured waveform stored in the memory unit 32 with a reference waveform previously stored in the memory unit 32. Specifically, it is assumed that the measured waveform shown in graph G1 as measured waveform example 1 in Fig. 3 is obtained at a certain inspection point, and data showing that there is no insulation defect at that inspection point is stored as the reference waveform shown in graph G10 as reference waveform example 1.

[0019] In this case, the judgment unit 34 judges whether the insulation is good or bad by, for example, comparing the areas of graph G1 and graph 10, as shown in judgment example 1. This judgment example 1 shows an example of the judgment result when the product is judged to be good. Furthermore, the judgment of whether the insulation is good or bad can also be made using a method other than area comparison, or by combining multiple methods.

[0020] 3 is obtained as a second example of a measured waveform, and a reference waveform as shown in graph G20 is stored as a second example of a reference waveform. In this case, the judgment unit 34 judges whether the insulation is good or bad by, for example, comparing the areas of graph G2 and graph G20, as shown as judgment example 2. This judgment example 2 shows an example of the judgment result when a defective product is judged. Note that, although the reference waveforms are stored in advance in correspondence with each inspection location, the same reference waveform may be used for different inspection locations, so there are not necessarily as many reference waveforms as there are inspection locations.

[0021] The output unit displays the insulation pass / fail judgment results for the inspection points and graphs of the judgment results shown in FIG. 3 on a display 37 via a display circuit (not shown), allowing the operator to check the results of the insulation test. At this time, the output unit can also display the progress of the insulation test on the display 37. The output unit can also output the judgment results and test time via communication to the management device 10 that manages the process. In this embodiment, the voltage control unit, measurement unit 33, judgment unit 34, and output unit described above are realized by software by executing a program on a microcomputer (not shown), but some or all of them can also be configured by hardware.

[0022] Next, the operation and effects of the above-described configuration will be described. First, the flow of the test process in a conventional general method used when conducting an insulation test on the coil 6 will be described with reference to Fig. 4. Hereinafter, for convenience, the conventional method of conducting an insulation test individually for each inspection point will be referred to as the individual determination method, and each part will be marked with "A" to distinguish it from the embodiment.

[0023] In the individual judgment method, the armature 7A is positioned, the application path is switched to correspond to the first inspection point, and then a measurement start command is output from the PLC 2A. When the measurement start command is received, the measuring device 3A reads out the reference waveform corresponding to that inspection point and starts charging, and when charging is complete, applies voltage, judges the quality of the insulation based on the measured charge amount, and outputs the result, thereby completing one insulation test.

[0024] For example, if n insulation tests are to be performed, this process is repeated n times to complete the inspection for one armature 7A. Note that although the order of the processes may differ slightly, such as when a reference waveform is read out during the judgment, in the individual judgment method, each process is basically carried out in series one after the other.

[0025] However, this individual evaluation method takes time because it requires reading out a reference waveform and outputting the evaluation result for each insulation test. As a result, it is necessary to install multiple insulation test facilities at actual manufacturing sites to prevent the insulation test from becoming a bottleneck, which increases costs. Furthermore, when performing insulation tests during mass production of armatures 7 as in this embodiment, there is a strong demand for reducing the time required for the insulation test because there are many test targets and each armature 7 has multiple test points.

[0026] Therefore, in this embodiment, the time required for the insulation test of the coil 6 is reduced as follows. Below, the process will be described with reference to the processing on the PLC 2 side shown in FIG. 5, the processing on the measuring instrument 3 side shown in FIG. 6, and the flow of the test process according to this embodiment shown in FIG. 7. It is assumed that the number of insulation tests and the association of the reference waveforms used in each test are preset in the measuring instrument 3 before the insulation test begins. Furthermore, although the processing on the measuring instrument 3 side is performed by each processing unit, such as the voltage control unit, measurement unit 33, judgment unit 34, and output unit, the following description will focus mainly on the measuring instrument 3 for simplicity. For convenience, the method according to this embodiment will be referred to as the comprehensive judgment method.

[0027] First, in the preparation stage before starting the insulation test, the armature 7 to be inspected is placed in a predetermined position and connected to the switch 8. These tasks are performed by an operator, and when the tasks are completed, a start command is given to the PLC 2. Then, as shown in Fig. 5, the PLC 2 determines whether or not a start command has been input (S1), and if a start command has not been input (S1: NO), it waits as is, but if a start command has been input (S1: YES), it outputs a measurement start command to the measuring instrument 3 (S2).

[0028] In response to this, the measuring instrument 3 determines whether or not a measurement start command has been received (S11), as shown in Fig. 6. If the measurement start command has not been received (S11: NO), the measuring instrument 3 remains in standby mode. However, if the measurement start command is received (S11: YES), the measuring instrument 3 reads out all of the reference waveforms stored in the memory unit 32 at once (S12). At this time, the measuring instrument 3 reads out all of the reference waveforms to be used in the n insulation tests from the memory unit 32 and stores them in a temporary storage area that can be accessed at high speed, such as RAM. The processing in step S12 corresponds to a reading step, and is performed during the first measurement.

[0029] Next, the measuring device 3 starts charging the capacitor 35b (S13), and when charging is complete, applies a voltage (S14). This step S14 corresponds to the application step. At this time, the measuring device 3 also starts measuring electrical energy. Therefore, in this embodiment, the period from when the voltage is applied until the storage of the measured waveform is completed, as described below, corresponds to the measurement step.

[0030] When the application step is completed, the measuring instrument 3 notifies the PLC 2 of the completion of application (S15). Then, as shown in FIG. 5, the PLC 2 determines whether or not it has received the notification of application completion (S3), and if it has not received the notification (S3: NO), it waits. On the other hand, if it has received the notification (S3: YES), the PLC 2 causes the switch 8 to switch the path so that the application path becomes the next test point (S4). This step S4 corresponds to the switching step. In other words, unlike the individual judgment method described above, the insulation test apparatus 1 performs the switching step when the application of voltage is completed, in other words, before judging the quality of the insulation and outputting the judgment result.

[0031] After notifying the completion of application, the measuring instrument 3 stores the measured waveform (S16) as shown in FIG. 6, and then charges the capacitor 35b (S17) and determines whether the insulation is good or bad (S19) in parallel. That is, the insulation test apparatus 1 performs the charging step (S17) of charging the capacitor 35b and the determining step (S19) of determining whether the insulation is good or bad in parallel. At this time, since the switching step (S4) is being performed on the PLC 2 side, the switching step is performed in parallel with the charging step and the determining step in the insulation test apparatus 1. Note that the completion timing of each step may differ.

[0032] Then, when measuring instrument 3 determines whether the insulation is good or bad in step S19, it stores the determination result in storage unit 32 (S20). That is, the process relating to the determination ends at step S20.

[0033] On the other hand, after starting charging in step S17, when charging is completed, the measuring device 3 notifies the PLC 2 of the completion of charging (S18). At this time, as shown in Fig. 5, the PLC 2 determines whether or not the notification of charging completion has been received (S5), and if the notification of charging completion has not been received (S5: NO), it waits, but if the notification of charging completion has been received (S5: YES), it outputs a measurement start command (S6). In other words, the insulation test apparatus 1 outputs a measurement start command to instruct the start of the next measurement when the notification of charging completion is received or when the switching of the switch 8 is completed, whichever is later.

[0034] Next, if the preset n number of measurements have not been completed (S7: NO), PLC 2 proceeds to step S3 and waits for the next notification of charging completion. Note that if the n number of measurements have been completed (S7: YES), PLC 2 ends the process.

[0035] Furthermore, after notifying the completion of charging, if n measurements have not been completed (S21: NO), the measuring device 3 further determines whether the next measurement start signal has been received (S22), and if the measurement start signal has not been received (S22: NO), it waits. On the other hand, if the measuring device 3 has received a measurement start signal (S22: YES), it proceeds to step S14 and starts an insulation test on the next test point. Furthermore, if n measurements have been completed (S21: YES), the measuring device 3 performs a comprehensive output that outputs the judgment results of each test point together (S23), and ends the process. This step S23 corresponds to a comprehensive judgment output process. This allows the operator or management device to grasp the measurement results of all test points.

[0036] In this way, the insulation test apparatus 1 first reads out the reference information required for n measurements all at once, switches the application path when the voltage application is complete, and simultaneously charges the capacitor 35b and judges whether the insulation is good or bad. This eliminates the time required to read out the reference waveform, wait for charging, and wait for judgment at each test point, as shown in the comprehensive judgment method in Figure 7. As a result, the time required for insulation testing from the second measurement onwards can be significantly reduced compared to the individual judgment method.

[0037] As a result, as shown in Fig. 8, when an insulation test was actually performed on the armature 7, which had 18 inspection points set up, it was confirmed that the total inspection time could be reduced to roughly one-quarter, with the total inspection time using the individual judgment method being T1 and the total inspection time using the comprehensive judgment method being T10.

[0038] Furthermore, as can be seen from Fig. 7, the more inspections are performed with the comprehensive judgment method, the more efficient the time reduction becomes. When an insulation test was actually performed on armature 7, which had 32 inspection points set up, it was confirmed that the total inspection time could be reduced to roughly one-fifth, with the total inspection time using the individual judgment method being T2 and the total inspection time using the comprehensive judgment method being T20.

[0039] Furthermore, because the adoption of the comprehensive judgment method has enabled a significant reduction in the total inspection time, it has become possible to handle a process that previously required two insulation test facilities with one insulation test facility.In other words, it has been confirmed that the comprehensive judgment method is a method that can efficiently perform insulation tests while fully satisfying the required manufacturing efficiency, for example, in actual manufacturing sites such as mass production of brushed motors.

[0040] According to the embodiment described above, the following effects can be obtained. The insulation inspection method according to the embodiment is for determining whether the insulation of the insulating coating 4 of a coil 6 formed by winding a conductor wire 5 having the insulating coating 4 on its surface is good or bad, and includes a switching step for switching the application path to the coil 6, a charging step for charging the voltage to be applied to the coil 6, an application step for applying the charged voltage to the coil 6, and a determination step for determining whether the insulation of the insulating coating 4 is good or bad by comparing a measured waveform generated based on the attenuation mode of electrical energy generated due to partial discharge in the coil 6 with a pre-prepared reference waveform, in which the switching step is performed when the application step is completed, the charging step is performed in parallel with the switching step, and the determination step is performed in parallel with at least one of the switching step and the charging step.

[0041] In this way, by performing several processes in parallel, the inspection time for one insulation test can be shortened, that is, the time required for the insulation test of the coil 6 can be shortened.

[0042] Furthermore, the insulation test method further includes a readout process in which a plurality of test points are set in the coil 6 and a reference waveform prepared in advance is read out all at once for the plurality of test points, the readout process being performed once at the first measurement, and the judgment process being performed continuously for all test points while switching the application path. This contributes greatly to reducing the manufacturing time as the number of test objects increases, and is particularly useful in mass production because it allows insulation tests to be performed continuously for a plurality of test points while reducing the time.

[0043] The conventional individual judgment method allows the judgment results for each inspection point to be grasped each time, so it is thought to be suitable for literally individual inspections. However, during mass production, the assumption is that basically most products will be good and there will be very few defective products, so there is thought to be little need to output the judgment results individually.

[0044] In contrast, the comprehensive evaluation insulation test method not only shortens the test time for a single insulation test by carrying out the charging process and the evaluation process in parallel, but also contributes significantly to time reduction as the number of tests increases, making it suitable for insulation testing during mass production.

[0045] Furthermore, since the comprehensive judgment method makes it possible to perform insulation tests on multiple inspection points consecutively while reducing the time, the more inspection points that are set as one inspection target, such as the armature 7, the more it contributes to reducing the total inspection time. In other words, the reason why the comprehensive judgment method of insulation testing is effective in mass production is because there is a technical basis that, since most products are considered to be non-defective, there is only a small disadvantage in performing insulation tests on multiple points consecutively and repeatedly, and it is not simply a change in the process order from the individual judgment method.

[0046] The insulation test method further includes a step of notifying completion of charging when charging is completed, and the application step is performed when the charging step is completed or when the switching step is completed, whichever is later. This makes it possible to start the next measurement when voltage application becomes possible, reducing waiting time during testing and shortening inspection time.

[0047] The insulation test device 1 judges the quality of the insulation of a coil 6 formed by winding a conductor wire 5 having an insulating coating 4 on its surface, and includes a control unit 21 that outputs a command to start measurement and controls switching of the application path to the coil 6, a power supply control unit 31 that applies voltage based on a command from the control unit 21, a measurement unit 33 that measures the electrical energy associated with partial discharge in the coil 6, and a judgment unit 34 that judges the quality of the insulation by comparing a measured waveform generated based on the attenuation pattern of the electrical energy with a reference waveform prepared in advance. The control unit 21 switches the application path when the voltage application is completed, and the power supply control unit 31 starts charging for the next measurement in parallel with the path switching by the control unit 21, and the judgment unit 34 judges the quality of the insulation in parallel with the charging by the power supply control unit 31.

[0048] With an insulation testing device configured in this way, various effects similar to those of the insulation testing method described above can be obtained, such as the fact that processes that were previously performed serially can now be performed in parallel, thereby shortening the testing time for a single insulation test.

[0049] In the embodiment, an example has been shown in which the processing of the measuring device 3 is changed between the first measurement and the second and subsequent measurements among multiple measurements, but it is also possible to configure the PLC 2 to output a preparation command to read out the reference waveform all at once and charge for the first measurement, notify the PLC 2 that charging is complete, and then output a measurement start command in response to that notification, so that the processing on the measuring device 3 side after the measurement start command is output can be made common for all measurements.

[0050] In the embodiment, an example in which the insulation test apparatus 1 is configured with the PLC 2 and the measuring instrument 3 has been shown, but the insulation test apparatus 1 can also be configured as a stand-alone device. Also, the power supply unit 35 and the detection unit can be provided as independent devices, and the devices can be controlled by, for example, a personal computer. In other words, the configuration of the insulation test apparatus 1 is not limited to that shown in the drawings.

[0051] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. [Explanation of symbols]

[0052] In the drawing, 1 indicates an insulation test device, 4 indicates an insulating coating, 5 indicates a conductor wire, 6 indicates a coil, 21 indicates a control unit, 31 indicates a power supply control unit, 33 indicates a measurement unit, 34 indicates a judgment unit, G1 and G2 indicate graphs (measured waveforms), and G10 and G20 indicate graphs (reference waveforms).

Claims

1. An insulation inspection method for determining whether the insulation of a coil (6) formed by winding a conductor wire (5) having an insulating coating (4) on its surface is good or bad, comprising the steps of: A switching step (S4) of switching a path for applying a voltage to the coil; a charging step (S17) of charging a voltage to be applied to the coil; an application step (S14) of applying the charged voltage to the coil; a determination step (S19) of determining whether the insulation is good or bad by comparing measurement waveforms (G1, G2) generated based on the attenuation state of electrical energy generated due to partial discharge in the coil with reference waveforms (G10, G20) prepared in advance, The switching step is performed when the application step is completed, The charging step is performed in parallel with the switching step, The insulation inspection method includes performing the determining step in parallel with at least one of the switching step and the charging step.

2. The coil has a plurality of test points, The method further includes a reading step of collectively reading out the reference waveforms prepared in advance for a plurality of test points, The reading step is performed at the time of the first measurement, 2. The insulation inspection method according to claim 1, wherein the determining step is performed continuously for all test points while switching the path to which the voltage is applied.

3. 3. The insulation inspection method according to claim 2, further comprising a comprehensive judgment output step of collectively outputting the judgment results of the insulation quality for a plurality of measurement points.

4. The method further includes a step of notifying the completion of charging when the charging is completed, 2. The insulation inspection method according to claim 1, wherein the applying step is performed at the later of the time when the charging step is completed and the time when the switching step is completed.

5. An insulation inspection device (1) for determining whether the insulation of a coil (6) formed by winding a conductor wire (5) having an insulating coating (4) on its surface is good or bad, comprising: a control unit (21) that outputs a command to start measurement and controls switching of a path for applying a voltage to the coil; a power supply control unit (31) that applies a voltage based on a command from the control unit; a measuring unit (33) for measuring electrical energy generated in association with partial discharge of the coil; a determination unit (33) for determining whether insulation is good or bad by comparing a measurement waveform generated based on the attenuation state of electrical energy with a reference waveform prepared in advance, the control unit switches the path to which the voltage is applied when the application of the voltage is completed; the power supply control unit starts charging for the next measurement in parallel with the path switching by the control unit; The determination unit is an insulation inspection device that determines whether the insulation is good or bad in parallel with charging by the power supply control unit.

Images