Test system, partial discharge test method, partial discharge test program, and switching device

Abstract

To improve accuracy of an impulse PD test in a partial discharge test.SOLUTION: A test system 1 includes a partial discharge detector 2 and a switching device 3 that switches a connection state between a measurement terminal 4 of a DUT 5 and the partial discharge detector 2. The partial discharge detector 2 includes: a voltage acquisition unit that acquires, via the switching device 3, a voltage signal corresponding to an output voltage when a test voltage is applied to the DUT 5; a current acquisition unit that acquires, via the switching device 3, a current signal when the test voltage is applied to the DUT 5; a partial discharge determination unit that determines whether or not partial discharge occurs using the current signal; and a voltage specification unit that specifies a partial discharge voltage using the voltage signal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a test system, a partial discharge test method, a partial discharge test program, and a switching device. [Background technology]

[0002] Conventionally, various tests are conducted to evaluate safety performance before shipping electrical equipment, electronic components, batteries, etc. These tests include, for example, a withstand voltage test, an insulation resistance test, and a partial discharge test.

[0003] For example, Patent Document 1 discloses a test system that connects multiple test objects (hereinafter also referred to as "DUTs: Devices Under Test") to multiple measuring instruments via relays, and can perform multiple tests such as those described above while changing the connection state between the measuring instruments and the DUTs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-220799 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, one of the safety evaluation tests for inductor coils, motor coils, etc. is the partial discharge test, which evaluates the insulation state by detecting potential defects in the windings. Known partial discharge tests include, for example, the AC partial discharge test (hereinafter referred to as the "ACPD test") and the impulse partial discharge test (hereinafter referred to as the "impulse PD test"). ACPD is a test to determine whether a partial discharge occurs when a predetermined AC voltage is applied to the insulating part of the DUT. Impulse PD test is a test to determine whether a partial discharge occurs when a predetermined impulse voltage is applied to the insulating part. These partial discharge tests are defined by IEC standards and are conducted in accordance with these standards.

[0006] FIG. 12 is a diagram showing a conventional impulse PD test method. In the impulse PD test, for example, the power supply device 101 and the DUT 102 are connected, and an impulse voltage is applied between two windings connected at the neutral point (U phase and V phase are shown as an example in FIG. 12). The discharge current that flows at this time is detected by the current transformer 103, and the detected discharge current is analyzed by the partial discharge detector 104 to determine whether or not a partial discharge has occurred in the DUT 102. If the partial discharge detector 104 determines that a partial discharge has occurred, it acquires from the power supply device 101 via the communication line 105 the voltage value of the impulse voltage that was output from the power supply device 101 when the partial discharge occurred, and records the acquired voltage value as the partial discharge voltage.

[0007] Incidentally, when power supply device 101 and DUT 102 are connected to perform an impulse PD test, stray inductance and stray capacitance exist in the connection wire between power supply device 101 and DUT 102. Furthermore, stray inductance and stray capacitance exist in the winding of DUT 102 itself. Therefore, there is a risk that the generating end voltage output from power supply device 101 will differ from the receiving end voltage actually applied to DUT 102, potentially reducing the test accuracy. Furthermore, when the power supply device 101 and the DUT 102 are connected via a switching device (see, for example, Patent Document 1) to improve the efficiency of testing, the distance between the generating end and the receiving end becomes longer than when the power supply device 101 and the DUT 102 are directly connected, which further increases the error between the generating end voltage and the receiving end voltage.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a test system, a partial discharge test method, a partial discharge test program, and a switching device that can improve the accuracy of impulse PD tests in partial discharge tests. [Means for solving the problem]

[0009] A test system according to one aspect of the present invention comprises a partial discharge detector and a switching device that switches the connection state between the measurement terminal of the test object and the partial discharge detector, and the partial discharge detector comprises a voltage acquisition means that acquires, via the switching device, a voltage signal corresponding to the output voltage when a test voltage is applied to the test object, a current acquisition means that acquires, via the switching device, a current signal when the test voltage is applied to the test object, a partial discharge determination means that uses the current signal to determine whether a partial discharge has occurred, and a voltage identification means that identifies a partial discharge voltage using the voltage signal.

[0010] "Test systems" are used for a wide range of purposes and applications, such as product development, product quality inspection (line inspection), etc. For example, a test system can be used as a line inspection device (inspection equipment) used in line inspection.

[0011] A switching device according to one embodiment of the present invention comprises: a first external terminal to which a power supply device that generates a test voltage for a partial discharge test is connected; a second external terminal to which a measurement terminal of a test object is connected; a third external terminal to which a partial discharge detector is connected; a first bus having low-voltage and high-voltage side buses; a second bus having low-voltage and high-voltage side buses; a first switch that switches the connection state between the first external terminal and the first bus; a second switch that switches the connection state between the second external terminal and the first bus and the second bus; a third switch that switches the connection state between the third external terminal and the second bus; and voltage detection means that is provided in an electrical path connecting the third external terminal and the second bus and that detects the output voltage when the test voltage is applied to the test object.

[0012] A partial discharge testing method according to one aspect of the present invention includes the steps of applying a test voltage to a measurement end of a test object via a switching device, acquiring a voltage signal via the switching device that corresponds to the output voltage when the test voltage is applied to the test object, acquiring a current signal via the switching device when the test voltage is applied to the test object, determining whether a partial discharge has occurred using the current signal, and determining a partial discharge voltage using the voltage signal.

[0013] A partial discharge testing program according to one embodiment of the present invention is a program for a computer to execute the following steps: a voltage acquisition process for acquiring, via a switching device, a voltage signal corresponding to the output voltage when a test voltage generated in a power supply device is applied to a test object via the switching device; a current acquisition process for acquiring, via the switching device, a current signal when the test voltage is applied to the test object; a partial discharge determination process for determining whether or not a partial discharge has occurred using the current signal; and a voltage identification process for identifying a partial discharge voltage using the voltage signal. [Effects of the Invention]

[0014] The present invention has the effect of improving the accuracy of impulse PD testing in partial discharge testing. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing a schematic configuration of a test system according to an embodiment of the present invention; [Figure 2] 1 is a diagram illustrating an example of a configuration of a switching device according to an embodiment of the present invention. [Figure 3] FIG. 1 is a diagram illustrating a hardware configuration of a partial discharge detector according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing an example of functions of a partial discharge detector according to an embodiment of the present invention. [Figure 5]1 is a flowchart showing an example of a processing procedure for an impulse PD test according to an embodiment of the present invention. [Figure 6] 1 is a flowchart showing an example of a processing procedure for an impulse PD test according to an embodiment of the present invention. [Figure 7] FIG. 4 is a diagram showing an example of the open / closed states of switches when an impulse PD test is performed according to one embodiment of the present invention. [Figure 8] FIG. 1 is a diagram showing a simulation model that models a circuit from a power supply device according to an embodiment of the present invention to a measurement end of a DUT. [Figure 9] 8 is a diagram showing a voltage waveform at the measurement end of the DUT when an impulse voltage of 1,000 V is output from a power supply device to the simulation model shown in FIG. 7. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of a test system according to another embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing a schematic configuration of a test system according to another embodiment of the present invention. [Figure 12] FIG. 1 is a diagram schematically illustrating a conventional impulse PD test method. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a test system, a partial discharge test method, a partial discharge test program, and a switching device according to the present invention will be described below with reference to the drawings. In this embodiment, a motor is used as an example of a DUT (subject to test), but this is not limiting. The subject to test may be anything that can be subjected to a partial discharge test, and other examples include a coil (transformer), a semiconductor, etc.

[0017] Fig. 1 is a diagram showing a schematic configuration of a test system 1 according to one embodiment of the present invention. As shown in Fig. 1, the test system 1 includes a partial discharge detector 2 and a switching device 3. The test system 1 also includes a power supply device 6 that generates a test voltage to be applied to a DUT 5, and a control device 7 that performs overall control of the test system 1.

[0018] The power supply device 6 is a device that generates a voltage according to the test content. For example, in an impulse PD test of a partial discharge test, the power supply device 6 generates a high impulse voltage that complies with the standard as a test voltage. The power supply device 6 includes, for example, a known AC / DC converter and a DC / DC converter that can generate a voltage of a desired magnitude and type from power supplied from an external source such as a commercial power source.

[0019] The partial discharge detector 2 is a device that determines whether or not a partial discharge has occurred in the DUT 5 based on the discharge current of the DUT 5 when a test voltage is applied to the measuring end 4 of the DUT 5, and outputs the determination result. Details of the partial discharge detector 2 will be described later.

[0020] In this embodiment, the power supply device 6 and the partial discharge detector 2 are provided separately as separate units, but the present invention is not limited to this. For example, the power supply device 6 and the partial discharge detector 2 may be integrated and realized as a single device.

[0021] The switching device 3 switches the connection state between the power supply device 6 and the measuring end 4 of the DUT 5, and the connection state between the measuring end 4 of the DUT 5 and the partial discharge detector 2. The switching device 3 includes, for example, a plurality of switches. The open / closed states of these switches are controlled based on control commands from the control device 7, thereby forming an electrical path according to the test being performed. Details of the switching device 3 will be described later.

[0022] The control device 7 is an information processing device with a built-in computer. The control device 7 is realized by, for example, a notebook PC, a desktop PC, a tablet terminal, a smartphone, a server, a PLC (Programmable Logic Controller), etc. The control device 7 includes, for example, a CPU (Central Processing Unit: processor), a main memory, a secondary storage, and a communication interface. The control device 7 may also include an input device, an output device, etc.

[0023] The various functions realized by the control device 7 are stored in the form of a program in a secondary storage device, and the CPU reads this program into the main storage device and executes information processing and arithmetic operations to realize the various functions. The program may be pre-installed in the secondary storage device, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, optical disks, and semiconductor memories.

[0024] The control device 7 is communicatively connected to the partial discharge detector 2, the switching device 3, and the power supply device 6, and controls the test system 1 based on information acquired from these various devices and information input by the user. For example, the control device 7 controls the timing of the start of the test, the timing of the generation of the test voltage in the power supply device 6, the timing of the end of the partial discharge test, and the like, and controls the opening and closing of the switch of the switching device 3.

[0025] Next, the switching device 3 will be described with reference to the drawings. Fig. 2 is a diagram showing an example of the configuration of the switching device 3. Note that the connection relationship with the control device 7 is omitted.

[0026] 2, the switching device 3 includes a plurality of external terminals and a plurality of switches 10. The switching device 3 also includes a voltage detector 14 for detecting an output voltage when a test voltage is applied to the DUT 5, and a current detector 15 for detecting a current when the test voltage is applied to the DUT 5.

[0027] The voltage detector 14 is, for example, a voltage divider that divides and outputs the output voltage from the DUT 5. Furthermore, the voltage detector 14 is not limited to this example, and any sensor that can detect the output voltage (voltage waveform) when the test voltage is applied to the DUT 5 will suffice, and any known sensor can be appropriately adopted.

[0028] The current detector 15 detects, for example, a current flowing on the ground side. For example, the current detector 15 is a current sensor such as a current transformer. Furthermore, the current detector 15 is not limited to this example, and any sensor capable of detecting a current signal when a test voltage is applied to the DUT 5 will suffice, and any known sensor can be appropriately adopted.

[0029] The plurality of external terminals include, for example, a first external terminal 11, a second external terminal 12, and a third external terminal 13.

[0030] For example, a power supply device 6 is connected to the first external terminal 11. The first external terminal 11 is configured to be capable of inputting and outputting high voltages (for example, several thousand volts). The first external terminal 11 is connected to, for example, an output terminal of the power supply device 6 via a wire. The first external terminal 11 includes a first external positive terminal and a first external negative terminal. The first external positive terminal is connected to the positive output terminal of the power supply device 6, and the first external negative terminal is connected to the negative output terminal of the power supply device 6.

[0031] The measurement end 4 of the DUT 5 is connected to the second external terminal 12. Fig. 2 shows an example of a connection when the DUT 5 is a three-phase motor in which U-phase, V-phase, and W-phase coils are wound around a stator core. The second external terminal 12 includes a second external terminal 12a to which one end of the U-phase coil is connected, a second external terminal 12b to which one end of the V-phase coil is connected, a second external terminal 12c to which one end of the W-phase coil is connected, and a second external terminal 12d to which the ground of the three-phase motor is connected. Each of the second external terminals 12a to 12d includes a second external output terminal and a second external input terminal.

[0032] The partial discharge detector 2 is connected to the third external terminal 13. For example, the third external terminal 13 includes, inside the switching device 3, a third external terminal 13a connected to a voltage detector 14 and a third external terminal 13b connected to a current detector 15.

[0033] The third external terminal 13a includes a third external high-voltage terminal connected to the high-voltage side output electric circuit of the voltage detector 14, and a third external low-voltage terminal connected to the low-voltage side output electric circuit of the voltage detector 14. The high-voltage input terminal of the partial discharge detector 2 is connected to the third external high-voltage terminal, and the low-voltage input terminal of the partial discharge detector 2 is connected to the third external low-voltage terminal. The current input terminal of the partial discharge detector 2 is connected to the third external terminal 13b. A high-pass filter 8 may be provided in the electric circuit connecting the third external terminal 13b and the current input terminal of the partial discharge detector 2.

[0034] The switching device 3 includes a first bus BS1 and a second bus BS2. The first bus BS1 includes a high-voltage bus H corresponding to a high voltage and a low-voltage bus L corresponding to a low voltage. The second bus BS2 includes a high-voltage bus H' corresponding to a high voltage and a low-voltage bus L' corresponding to a low voltage. The low-voltage bus L of the first bus BS1 is, for example, grounded.

[0035] The switches 10 include, for example, a plurality of switches that switch the connection state between the power supply device 6 and the measurement end 4 of the DUT 5. The switches 10 also include a plurality of switches that switch the connection state between the measurement end 4 of the DUT 5 and the partial discharge detector 2. Examples of the switch 10 include mechanical switches such as relays and contactors. Alternatively, the switch 10 may be a semiconductor switch such as a power transistor.

[0036] Specifically, the plurality of switches 10 includes a first switch group 16, a second switch group 17, and a third switch group 18.

[0037] The first switch group 16 switches the connection state between the first external terminal 11 and the first bus BS1. For example, the first switch group 16 includes a high-voltage side switch provided between the first external positive terminal and the high-voltage bus H of the first bus BS1, and a low-voltage side switch provided between the first external negative terminal and the low-voltage bus L of the first bus BS1.

[0038] The second switch group 17 includes output side switches SW1-1, SW2-1, SW3-1, and SW4-1 arranged between the first bus BS1 and the second external output terminal, and input side switches SW1-2, SW2-2, SW3-2, and SW4-2 arranged between the second bus BS2 and the second external input terminal.

[0039] The output-side switches SW1-1, SW2-1, SW3-1, and SW4-1 are configured to be able to switch the connection between the second external output terminal and the high-voltage bus H or the low-voltage bus L of the first bus BS1. The input-side switches SW1-2, SW2-2, SW3-2, and SW4-2 are configured to be able to switch the connection between the second external input terminal and the high-voltage bus H' or low-voltage bus L' of the second bus BS2.

[0040] The third switch group 18 is provided between the second bus BS2 and the third external terminal 13a. The third switch group 18 includes a high-voltage side switch provided between the third external high-voltage terminal and the high-voltage bus H', and a low-voltage side switch provided between the third external low-voltage terminal and the low-voltage bus L'.

[0041] A switch control circuit (not shown) controls the opening and closing of the switch 10 based on a control command from the control device 7 (see FIG. 1), and forms an electric circuit according to the inspection or test. As described above, the switching device 3 includes the first bus BS1 and the second bus BS2, and the switch 10 is provided between the first bus BS1 and the second bus BS2 and the first external terminal 11, the second external terminal 12, and the third external terminal 13. This configuration simplifies the configuration of the electrical path, and makes it easy to understand the opening and closing control of the switch 10 for forming the electrical path.

[0042] Next, the partial discharge detector 2 according to this embodiment will be described with reference to the drawings. Fig. 3 is a diagram showing the hardware configuration of the partial discharge detector 2. As shown in Fig. 3, the partial discharge detector 2 includes, for example, a voltage input terminal 21, an A / D converter 22, a current input terminal 23, an A / D converter 24, and a data processing circuit 25.

[0043] The voltage input terminal 21 is connected to the third external terminal 13a via a cable. Specifically, the voltage input terminal 21 includes a high voltage input terminal and a low voltage input terminal. The A / D converter 22 samples the voltage signal input from the voltage input terminal 21 at a predetermined sampling period, thereby converting the analog voltage signal into a digital voltage signal Vout and outputting it. Note that a known device such as an amplifier may be installed between the voltage input terminal 21 and the A / D converter 22.

[0044] The current input terminal 23 is connected to the third external terminal 13b via a cable. The A / D converter 24 samples the current signal input from the current input terminal 23 at a predetermined sampling period, thereby converting the analog current signal into a digital current signal Id and outputting it. Note that a known device such as an amplifier may be installed between the current input terminal 23 and the A / D converter 24.

[0045] The data processing circuit 25 determines the presence or absence of partial discharge using the voltage signal Vout output from the A / D converter 22 and the current signal Id output from the A / D converter 24. The data processing circuit 25 is a computer, and includes, for example, a CPU (Central Processing Unit: processor), a main memory, a secondary storage (secondary storage), etc. The data processing circuit 25 is realized by, for example, a microcomputer, a field-programmable gate array (FPGA), a programmable logic controller (PLC), or the like.

[0046] A secondary storage device is a non-transitory computer-readable storage medium. Examples of secondary storage devices include semiconductor memory, such as flash memory and solid-state drives (SSDs). Other examples of secondary storage devices include magnetic disks (HDDs), optical disks (CD-ROMs, DVD-ROMs, etc.), and magneto-optical disks. The secondary storage device stores various data and programs for implementing various functions of the data processing circuit 25, which will be described later. The secondary storage device also stores various data acquired in the partial discharge test. A plurality of secondary storage devices may be provided, and the programs and data for realizing the functions described below may be stored separately in each secondary storage device.

[0047] The partial discharge detector 2 may also include an input operation unit 26, a display 27, a communication interface 28, an external interface 29, and the like.

[0048] The input operation unit 26 is a man-machine interface for the user to input instructions. Examples of the input operation unit 26 include various buttons and a touch panel. The display 27 is, for example, a liquid crystal display, and displays the data processed by the data processing circuit 25, the determination results, and the like.

[0049] The communication interface 28 is an interface for communicating with other devices and transmitting and receiving information. For example, the communication interface 28 communicates with other devices (e.g., the power supply device 6, the control device 7, etc.) via wired or wireless communication. Examples of wireless communication include communication via lines such as Bluetooth (registered trademark), Wi-Fi, mobile communication systems (3G, 4G, 5G, 6G, LTE, etc.), and wireless LAN. Examples of wired communication include serial communication such as RS-232C and RS-485, CAN (Controller Area Network), Ethernet, and wired LAN (Local Area Network).

[0050] The external interface 29 is an interface for connecting an external device. Examples of external devices include a USB memory, an external HDD, and an SD card. Although only one external interface 29 is shown in the example shown in FIG. 3, multiple external interfaces 29 may be provided.

[0051] The data processing circuit 25, input operation unit 26, display 27, communication interface 28, and external interface 29 are connected to one another, for example, directly or indirectly via a bus.

[0052] Fig. 4 is a diagram showing an example of functions provided in the partial discharge detector 2. As shown in Fig. 4, the partial discharge detector 2 has the functions of a voltage acquisition unit 31, a current acquisition unit 32, a partial discharge determination unit 33, and a voltage identification unit 34. These various functions are realized, for example, by the data processing circuit 25. For example, a series of processes for realizing these various functions is stored in the form of a program in a secondary storage device, and the CPU reads this program into the main storage device and executes information processing and arithmetic processing to realize the various functions. Note that the program may be installed in advance in a secondary storage device, provided in a state stored in a non-transitory computer-readable storage medium, or distributed via wired or wireless communication means.

[0053] The voltage acquiring unit 31 acquires a voltage signal corresponding to the output voltage when the test voltage is applied to the DUT 5. For example, the voltage acquiring unit 31 acquires the digital voltage signal Vout output from the A / D converter 22.

[0054] The current acquiring section 32 acquires a current signal when the test voltage is applied to the DUT 5. For example, the current acquiring section 32 acquires a digital current signal Id output from the A / D converter 24.

[0055] The partial discharge determination unit 33 uses the current signal Id to determine whether or not a partial discharge is occurring. The voltage identifying unit 34 identifies the partial discharge voltage using the voltage signal Vout acquired by the voltage acquiring unit 31.

[0056] The results of the partial discharge test are displayed on a display 27 by the data processing circuit 25, and are also transmitted to other devices (such as the power supply device 6 and the control device 7) via a communication interface . The display 27 displays, for example, a voltage waveform based on a voltage signal acquired by the voltage acquisition unit 31, a current waveform based on a current signal acquired by the current acquisition unit 32, partial discharge voltage, test results (whether partial discharge has occurred, pass / fail, etc.), various numerical values, etc.

[0057] Next, an impulse PD test performed by the test system 1 according to this embodiment will be described. FIGS. 5 and 6 are flowcharts showing an example of the processing procedure for the impulse PD test according to this embodiment. The following description will be given taking as an example a case where a test is performed between the U phase and V phase of the DUT 5. Note that the following processing is performed by the partial discharge detector 2, the power supply device 6, and the control device 7 transmitting and receiving necessary information via the communication interface 28. In the following explanation, a line inspection will be taken as an example, and an example will be given in which the voltage value of the impulse voltage is increased stepwise up to a specified upper limit value (for example, 1,000 V) and a final pass / fail judgment is made.

[0058] First, an electric circuit for an impulse PD test is formed (SA1) by controlling the opening and closing of the switch 10 of the switching device 3 based on a switching command from the control device 7. Fig. 7 is a diagram showing an example of the open / closed state of the switch 10 when an impulse PD test is performed.

[0059] Next, the power supply device 6 sets the voltage value of the impulse voltage for the partial discharge test in accordance with the test algorithm (test procedure / rules) (SA2).

[0060] Next, the power supply device 6 generates and outputs an impulse voltage of the set voltage value (SA3). As a result, the impulse voltage is applied between the U phase and the V phase of the DUT 5. The output voltage resulting from the application of the impulse voltage is detected by the voltage detector 14 and output to the partial discharge detector 2 via the third external terminal 13a.

[0061] In the partial discharge detector 2, a voltage signal input from a voltage input terminal 21 (see FIG. 3) is converted from an analog signal to a digital signal, and the digital voltage signal Vout is output to a data processing circuit 25. The data processing circuit 25 identifies the partial discharge voltage based on the voltage signal Vout (SA4). At this time, an impulse voltage may be applied from the power supply device 6 to the DUT 5 for a certain period of time, the voltage signal Vout at that time may be measured for the certain period of time, and the peak value (maximum value) of the voltage signal Vout may be identified as the partial discharge voltage.

[0062] Furthermore, the discharge current that flows due to the application of the impulse voltage is detected by the current detector 15 and output to the partial discharge detector 2 via the third external terminal 13b (SA5). In the partial discharge detector 2, the current signal Id input from the current input terminal 23 is converted from an analog signal to a digital signal, and the digital current signal Id is output to the data processing circuit 25.

[0063] The data processing circuit 25 uses the current signal Id to determine whether or not a partial discharge is occurring (SA6 in FIG. 6). As a result, if partial discharge has not occurred (SA6: NO), the data processing circuit 25 determines that the condition is normal (SA7) and proceeds to step SA9.

[0064] On the other hand, if a partial discharge has occurred (SA6: YES), the data processing circuit 25 determines whether an abnormality has occurred (SA8) and proceeds to step SA9.

[0065] In step SA9, the data processing circuit 25 records the determination result (SA9). At this time, the data processing circuit 25 records the determination result, in other words, the presence or absence of partial discharge, in association with the partial discharge voltage identified in step SA4. Furthermore, the data processing circuit 25 may also record the voltage value of the impulse voltage set in step SA2 in association with the determination result.

[0066] Next, the power supply device 6 determines whether the test is completed (SA10). For example, it determines whether the voltage value of the impulse voltage set in step SA2 has reached an upper limit (e.g., 1,000 V) specified in the test algorithm.

[0067] As a result, if the test is not completed (SA10: NO), the process returns to step SA2, the voltage value of the impulse voltage is set again according to the test algorithm, and the above-mentioned process is performed at the set voltage value.

[0068] Then, the test proceeds according to the test algorithm, and when it is determined in step SA10 that the test has ended (SA10: YES), the partial discharge detector 2 makes a pass / fail determination based on the determination results recorded in this test, specifically, information correlating the partial discharge voltage with the presence or absence of partial discharge occurrence (SA11). For example, the partial discharge detector 2 determines whether an abnormality has been determined (whether a partial discharge has occurred) when the partial discharge voltage is equal to or lower than a specified upper limit (e.g., 1,000 V) in all the determination results recorded in step SA9. If no abnormality has been determined as a result, a pass determination is made, and if an abnormality has been determined, a fail determination is made.

[0069] Next, the partial discharge detector 2 displays the test result on the display 27 to notify the user, and also notifies the control device 7 via the communication interface 28 (SA12). At this time, the test result may include the judgment result recorded in step SA9 in addition to the pass / fail judgment.

[0070] When the control device 7 receives the test results, it outputs a command to open the switch 10 to the switching device 3 (SA13) and ends the process. This opens the electrical circuit and puts the device into a standby state for the next test. If the next test is to be performed consecutively, the control device 7 may output an open / close command to the switching device 3 for the switch 10 according to the next test. This opens the electrical circuit for the next test, making it possible to start the next test promptly.

[0071] The above-described processing procedure for the impulse PD test is an example, and it is possible to delete unnecessary steps, add new steps, or rearrange the processing order without departing from the spirit of the present invention.

[0072] Furthermore, for example, in the above-described procedure, the power supply device 6 sets the voltage value of the impulse voltage, but the flow of the impulse PD test may be managed by, for example, the control device 7 or the partial discharge detector 2. Specifically, the control device 7 or the partial discharge detector 2 may set the voltage value of the impulse voltage according to a test algorithm and notify the power supply device 6 of the set voltage value, thereby applying the impulse voltage.

[0073] In the above-described processing procedure, the process of generating and applying an impulse voltage by the power supply device 6 and the various determinations by the partial discharge detector 2 have been described as a series of processes, but this is not limiting. For example, the process of applying an impulse voltage by the power supply device 6 and the determination process by the partial discharge detector 2 may be executed as separate processes. Furthermore, the determination process by the partial discharge detector 2 may be performed in real time during the test, or the test results may be obtained by storing the data in a non-volatile memory and performing the determination process afterwards.

[0074] Furthermore, the test algorithm and pass / fail judgment criteria for the impulse PD test described above are merely examples, and can be set appropriately depending on the operation. For example, impulse voltages of the same voltage value may be repeatedly applied to the DUT 5, and pass / fail determination may be made depending on whether partial discharge occurs within a reference number of times. In addition, the test and pass / fail judgment may be performed under a condition that combines the impulse voltage and the number of times it is applied (for example, if no partial discharge occurs after applying an impulse voltage of 1,000 V five times, the test is considered to have passed).

[0075] Furthermore, when applying impulse voltages of the same voltage value repeatedly, the output of the power supply device 6 may be adjusted so that the partial discharge voltage applied to the power receiving end of the DUT 5 becomes a specified value. By adjusting the voltage in this way, it becomes possible to efficiently perform highly accurate testing.

[0076] Furthermore, in an impulse PD test for research and development purposes, rather than a line inspection, it may be possible to monitor at what partial discharge voltage a partial discharge occurs, and to determine whether or not the partial discharge voltage at which a partial discharge occurs reaches a certain standard.

[0077] As described above, according to this embodiment, the following advantageous effects are achieved. That is, the test system 1 according to this embodiment includes a switching device 3 and a partial discharge detector 2. The partial discharge detector 2 includes, for example, a voltage acquiring unit 31 that acquires, via the switching device 3, a voltage signal corresponding to the output voltage when a test voltage is applied to a DUT 5, a current acquiring unit 32 that acquires, via the switching device 3, a current signal when the test voltage is applied to the DUT 5, a partial discharge determining unit 33 that determines whether or not a partial discharge is occurring using the current signal Id, and a voltage identifying unit 34 that identifies a partial discharge voltage using the voltage signal Vout.

[0078] In this way, since the partial discharge voltage is identified using the voltage signal Vout, even if the voltage value at the output end of the power supply device 6, in other words, the end where the impulse voltage is generated, differs from the voltage value at the receiving end of the DUT 5, partial discharge testing can be performed based on the voltage value at the receiving end of the DUT 5. This makes it possible to determine whether or not a partial discharge occurs when a standard-compliant impulse voltage is applied to the DUT 5, thereby improving the accuracy of the test. This makes it possible to properly prevent the release of defective DUTs 5, such as motors, that are the subject of testing, and improve the quality and safety of the DUTs 5. This ultimately makes it possible to improve the safety of products that use the DUTs 5.

[0079] Fig. 8 is a diagram showing a simulation model that models the circuit from the power supply device 6 to the measurement end 4 of the DUT 5. The simulation model shown in Fig. 8 includes a model 56 of the power supply device 6, a model 53 of the switching device 3, a wiring model 54 connecting the switching device 3 and the measurement end 4 of the DUT 5, and a model 55 of the DUT 5. As shown in Fig. 8, in the simulation model, stray inductance is simulated by a coil or resistor, and stray capacitance is simulated by a capacitor.

[0080] FIG. 9 is a diagram showing a voltage waveform at the measurement end 4 of the DUT 5 when an impulse voltage of 1,000 V is output from the power supply device 6 to the simulation model shown in FIG. In Figure 9, the dotted line represents the voltage waveform when there is no influence of the wiring and switching device 3, in other words, when the parameters of each component of model 53 and model 54 in the simulation model shown in Figure 8 are set to zero; the dotted line represents the voltage waveform when the parameters of each component of wiring model 54 are set to zero; and the solid line represents the voltage waveform when the actual test system 1 is simulated by setting the parameters of all components of model 53 of switching device 3, wiring model 54, and model 55 of DUT5.

[0081] As shown in Figure 9, when simulating the actual test system 1, the peak value of the voltage waveform generated was approximately 1,500 V, and it can be seen that the voltage difference between the impulse voltage generation end and the receiving end of the DUT 5 was quite large.

[0082] In the impulse PD test using the conventional method, the partial discharge voltage was determined by the impulse voltage at the output end (generation end) of the power supply device 6. Therefore, in the example shown in Fig. 9, a standard value of 1,000 V would suffice, but the voltage was guaranteed at 1,500 V, resulting in excessive quality. In contrast, in the test system 1 according to this embodiment, the partial discharge voltage is determined based on the output voltage of the DUT 5, not on the output terminal of the power supply device 6, so that it is possible to avoid excess quality, improve yield, and avoid unnecessary design changes.

[0083] Conversely to the above phenomenon, there is also a risk that the receiving end voltage may be lower than the impulse voltage at the output end (generation end) of the power supply device 6. In such a case, the product is guaranteed at a voltage value (e.g., 800 V) lower than the standard value (e.g., 1,000 V), which could result in products with potential defects being released onto the market. In such a case, the test system 1 according to this embodiment identifies the partial discharge voltage based on the output voltage of the DUT 5, making it possible to prevent products with potential defects from being released onto the market.

[0084] Furthermore, as a result of carrying out numerous simulations by changing the parameters in the simulation model shown in FIG. 8, we obtained new findings that the error in the impulse voltage between the generating end and the receiving end increases as the wiring becomes longer, and that the error in the impulse voltage increases as the parameter of the capacitor of DUT5 increases, in other words, as the inter-terminal capacitance increases.

[0085] For example, the terminal capacitance of hair pin motors, which have become mainstream in recent years (e.g., about 2,000 pF), is larger than that of round wire motors (e.g., about 400 pF). As a result, the voltage peak at the power receiving end of a hair pin motor is even larger than that of a round wire motor. Therefore, conventional methods can result in surplus quality, and in some cases, can erroneously guarantee a quality several hundred volts higher than the specified voltage.

[0086] Thus, the test system 1 according to this embodiment has a significant advantage in that it can solve problems such as excess quality when the DUT 5 has a terminal capacitance exceeding 2,000 pF. In other words, the test system 1 according to this embodiment is suitable for impulse PD testing of a DUT 5 (e.g., a rectangular wire coil, a rectangular wire motor, etc.) with a terminal capacitance exceeding 2,000 pF.

[0087] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the invention, and such modifications or improvements are also included in the technical scope of the present invention. Furthermore, the above embodiments may be combined as appropriate.

[0088] For example, although the present embodiment has been described with reference to a case where an impulse PD test is performed as a partial discharge test, the test system 1 may further include a function for performing an ACPD test. Here, ACPD is a test that measures the amount of discharge charge generated in the DUT 5 when an AC voltage is applied to an insulating portion of the DUT 5. This ACPD test is one type of partial discharge test, and is performed in accordance with IEC standards (e.g., IEC 60270, IEC 60034-27-1).

[0089] Fig. 10 shows an example of the configuration of a test system 1a equipped with an ACPD test function. As shown in Fig. 10, the test system 1a includes a power supply device 9 that generates and outputs a test voltage for the ACPD test. The power supply device 9 is connected to a DUT 5 via a switching device 3a. The switching device 3a has a fourth external terminal 11a to which the power supply device 9 is connected. In the switching device 3a, the fourth external terminal 11a is configured to be connectable to the first bus BS1 via a fourth switch group 19. Note that the connection relationship with the control device 7 is omitted.

[0090] An ACPD test sensor 40 is provided on the electrical path connecting the fourth external terminal 11a and the first bus BS1. The ACPD test sensor 40 has a circuit including, for example, a coil, a coupling capacitor, and a resistor, and is a sensor that detects a current (charge) flowing through the coupling capacitor due to discharge when a test voltage is applied to the DUT 5, and outputs a discharge detection signal corresponding to the detected current. Note that this sensor is publicly known, so a detailed description thereof will be omitted here.

[0091] The output signal of the ACPD test sensor 40 is output to the partial discharge detector 2 via the third external terminal 13c of the switching device 3a. The partial discharge detector 2 determines whether a partial discharge has occurred based on the discharge detection signal output from the ACPD test sensor 40. Note that any known method may be used as the determination method for the ACPD test.

[0092] In this way, the test system 1a is equipped with a configuration for performing an ACPD test, and by controlling the connection state of the switch 10 provided in the switching device 3a, it is possible to perform an impulse PD test and an ACPD test consecutively, thereby improving test efficiency.

[0093] Furthermore, the test system according to this embodiment may be configured as a system in which a plurality of test devices (for example, power supply devices, measuring instruments, etc.) and a DUT 5 are connected via a switching device 3b, as shown in FIG.

[0094] The test system 1c shown in FIG. 11 includes, as test devices, an insulation resistance test device 45 that performs an insulation resistance test and a withstand voltage test device 46 that performs a withstand voltage test. The insulation resistance test device 45 is a device that determines whether or not the insulation resistance value of an insulating portion of a DUT 5 is equal to or greater than a reference value when a high voltage (e.g., a DC voltage) is applied to the insulating portion of the DUT 5. The withstand voltage test device 46 is a device that determines whether or not a leakage current equal to or greater than a threshold value flows when a high voltage (e.g., an AC voltage) is applied to the insulating portion of the DUT 5 for a specified period of time. Note that the connection relationship with the control device 7 is omitted.

[0095] The partial discharge detector 2, power supply device 6, power supply device 9, insulation resistance test device 45, and withstand voltage test device 46 are configured to be connectable to multiple DUTs 5 via the switching device 3b. This makes it possible to connect a desired measuring device to a desired DUT 5 by controlling the opening and closing of the switch 10 of the switching device 3b and switching the electrical path in the switching device 3b. This makes it possible to perform multiple safety evaluation tests on the DUTs 5 continuously and automatically. This reduces the user's workload and shortens the test time. [Explanation of symbols]

[0096] 1: Test system 1a: Test system 1c: Test system 2: Partial discharge detector 3: Switching device 3a: Switching device 3b: Switching device 4: Measuring end 6: Power supply 7: Control device 8: High-pass filter 9: Power supply 10: Switch 11: First external terminal 11a: 4th external terminal 12: Second external terminal 12a: 2nd external terminal 12b: Second external terminal 12c: 2nd external terminal 12d: 2nd external terminal 13: Third external terminal 13a: Third external terminal 13b: 3rd external terminal 13c: 3rd external terminal 14: Voltage detector (voltage detection means) 15: Current detector (current detection means) 16: First switch group 17: Second switch group 18: Third switch group 19: 4th switch group 21: Voltage input terminal 22: A / D converter 23: Current input terminal 24: A / D converter 25: Data processing circuit 26: Input operation section 27: Display 28: Communication interface 29: External interface 31: Voltage acquisition unit (voltage acquisition means) 32: Current acquisition section (current acquisition means) 33: Partial discharge determination section (partial discharge determination means) 34: Voltage determination unit (voltage determination means) BS1: Bus No. 1 BS2: Bus No. 2

Claims

1. a partial discharge detector; a switching device for switching the connection state between the measurement terminal of the test object and the partial discharge detector; Equipped with The partial discharge detector comprises: a voltage acquiring means for acquiring, via the switching device, a voltage signal corresponding to an output voltage when a test voltage is applied to the test object; a current acquiring means for acquiring, via the switching device, a current signal when the test voltage is applied to the test object; a partial discharge determination means for determining whether or not a partial discharge has occurred using the current signal; a voltage identification means for identifying a partial discharge voltage using the voltage signal; A test system comprising:

2. The switching device a voltage detection means for detecting an output voltage when the test voltage is applied to the test object; a current detection means for detecting a current when the test voltage is applied to the test object; The test system of claim 1 , comprising:

3. a power supply device that generates the test voltage; The test system according to claim 1 , wherein the switching device switches a connection state between the measurement terminal of the test object and the power supply device.

4. The switching device a first external terminal to which a power supply device that generates a test voltage is connected; a second external terminal to which the measurement end of the test object is connected; a third external terminal to which the partial discharge detector is connected; a first bus having a low-side bus and a high-side bus; a second bus having a low-side bus and a high-side bus; a first switch that switches a connection state between the first external terminal and a first bus; a second switch that switches a connection state between the second external terminal and the first bus and the second bus; a third switch that switches a connection state between the third external terminal and a second bus; a voltage detection means provided in an electrical path for connecting the third external terminal and the second bus, the voltage detection means detecting an output voltage when the test voltage is applied to the test object; The test system of claim 1 , comprising:

5. The partial discharge detector comprises: a pass / fail determination unit that performs pass / fail determination based on information that associates the identified partial discharge voltage with the presence or absence of partial discharge occurrence; a notification means for notifying the pass / fail judgment result; The test system of claim 1 , comprising:

6. a first external terminal to which a power supply device that generates a test voltage for a partial discharge test is connected; a second external terminal to which a measurement end of the test object is connected; a third external terminal to which a partial discharge detector is connected; a first bus having a low-side bus and a high-side bus; a second bus having a low-side bus and a high-side bus; a first switch that switches a connection state between the first external terminal and a first bus; a second switch that switches a connection state between the second external terminal and the first bus and the second bus; a third switch that switches a connection state between the third external terminal and a second bus; a voltage detection means provided in an electrical path for connecting the third external terminal and the second bus, the voltage detection means detecting an output voltage when the test voltage is applied to the test object; A switching device comprising:

7. applying a test voltage to the measurement terminal of the test object via a switching device; a voltage acquiring step of acquiring, via the switching device, a voltage signal corresponding to an output voltage when the test voltage is applied to the test object; a current acquiring step of acquiring, via the switching device, a current signal when the test voltage is applied to the test object; a partial discharge determination step of determining whether or not a partial discharge has occurred using the current signal; a voltage identification step of identifying a partial discharge voltage using the voltage signal; Partial discharge test methods including:

8. a voltage acquisition process for acquiring, via a switching device, a voltage signal corresponding to an output voltage when a test voltage generated in the power supply device is applied to a test object via the switching device; a current acquisition process for acquiring, via the switching device, a current signal when the test voltage is applied to the test object; a partial discharge determination process for determining whether or not a partial discharge has occurred using the current signal; a voltage identification process for identifying a partial discharge voltage using the voltage signal; A computer for running partial discharge testing programs.

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