A device for measuring the onset voltage or extinction voltage of partial discharge.

Abstract

The present invention provides a device for measuring the initiation voltage or extinction voltage of a partial discharge that can suppress waveform deformation of the voltage due to the voltage for measurement passing through the connecting conductive path from the power supply to the object under test. [Solution] The partial discharge initiation voltage or extinction voltage measuring device 1 measures the partial discharge initiation voltage or extinction voltage of the object under test 11. The partial discharge initiation voltage or extinction voltage measuring device 1 comprises a power supply unit 2 that outputs a voltage for measurement, and a plurality of connecting conductive paths 31, 32 that electrically connect a plurality of output terminals 21, 22 of the power supply unit 2 to a plurality of connection terminals 111, 112 of the object under test 11, respectively. The plurality of connecting conductive paths 31, 32 have busbars, divided conductors or hollow conductors and have a length of 1 m or less.

Description

[[Technical Field]]

[0001] The present invention relates to an apparatus for measuring a partial discharge inception voltage or a partial discharge extinction voltage. [[Background Art]]

[0002] Patent Literature 1 discloses a partial discharge detection device that detects whether partial discharge occurs when a voltage generated from an impulse power supply is applied to a winding as an object to be measured. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Literature 1]] Japanese Unexamined Patent Publication No. 2021-105533 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, in the partial discharge detection device described in Patent Literature 1, no consideration is given to the connecting conductive path that electrically connects the impulse power supply and the winding, so there is a possibility that the voltage waveform deforms as the impulse voltage propagates through the connecting conductive path. Therefore, the partial discharge detection device described in Patent Literature 1 has room for improvement from the viewpoint of applying a voltage having a desired waveform such as an impulse voltage to an object to be measured.

[0005] The present invention has been made in view of the foregoing circumstances, and an object of the present invention is to provide an apparatus for measuring a partial discharge inception voltage or a partial discharge extinction voltage that can suppress deformation of a voltage waveform caused when a voltage for measurement passes through a connecting conductive path from a power supply unit to an object to be measured. [[Means for Solving the Problem]]

[0006] To achieve the above objective, the present invention provides a device for measuring the initiation voltage or extinction voltage of a partial discharge of an object under test, comprising: a power supply unit that outputs a voltage for the measurement; and a plurality of connecting conductive paths that electrically connect a plurality of output terminals of the power supply unit to a plurality of connection terminals of the object under test, wherein the plurality of connecting conductive paths have busbars, divided conductors, or hollow conductors, and have a length of 1 m or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a device for measuring the initiation voltage or extinction voltage of a partial discharge that can suppress the deformation of the voltage waveform caused by the voltage for measurement passing through the connecting conductive path from the power supply to the object under measurement. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of a measuring device and an object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the first embodiment. [Figure 2] This is a plan view of the measuring device and the object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the first embodiment. [Figure 3] This is a cross-sectional view taken along the line III-III in Figure 2. [Figure 4] This is a cross-sectional view taken along the line IV-IV in Figure 2. [Figure 5] This is a front view of the measuring device and the object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the first embodiment. [Figure 6] This is an exploded plan view of the power supply unit, the first and second connecting conductive circuits, and the object to be measured in the first embodiment. [Figure 7] This graph shows the difference in voltage waveforms when passing through a conductive path 1 m long and when passing through a conductive path 100 m long, according to the first embodiment. [Figure 8]This graph shows the difference in voltage waveforms in the first embodiment when passing through a conductive path with a skin effect coefficient of 1 μs / rad and when passing through a conductive path with a skin effect coefficient of 100 μs / rad. [Figure 9] This is a plan view of the measuring device and the object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the second embodiment. [Figure 10] This is a plan view of the measuring device and the object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the third embodiment. [Figure 11] This is a plan view of the hollow busbar in the fourth embodiment. [Figure 12] This is a side view of the hollow busbar in the fourth embodiment. [Figure 13] This is a cross-sectional view along the longitudinal direction of the hollow wire in the fifth embodiment. [Figure 14] This is a cross-sectional view in the fifth embodiment, perpendicular to the longitudinal direction of the hollow wire. [Figure 15] This is a plan view of the measuring device and the object to be measured for measuring the initiation voltage or extinction voltage of partial discharge in the sixth embodiment. [Figure 16] This is a cross-sectional view perpendicular to the longitudinal direction of the Litz wire in the sixth embodiment. [Modes for carrying out the invention]

[0009] [First Embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 8. The embodiments described below are presented as preferred specific examples for carrying out the present invention, and while some parts specifically illustrate various technically preferable technical matters, the technical scope of the present invention is not limited to these specific embodiments.

[0010] FIG. 1 is a configuration diagram of an apparatus 1 for measuring a partial discharge inception voltage or extinction voltage and a measured object 11 according to the present embodiment. FIG. 2 is a plan view of the apparatus 1 for measuring a partial discharge inception voltage or extinction voltage and the measured object 11. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a front view of the apparatus 1 for measuring a partial discharge inception voltage or extinction voltage and the measured object 11.

[0011] As shown in FIG. 1, the apparatus 1 for measuring a partial discharge inception voltage or extinction voltage is an apparatus for measuring electrical insulation of a measured object 11 having a plurality of conductors insulated from each other. The apparatus 1 for measuring a partial discharge inception voltage or extinction voltage according to the present embodiment measures the partial discharge inception voltage or partial discharge extinction voltage of the measured object 11. Specifically, the apparatus 1 for measuring a partial discharge inception voltage or extinction voltage according to the present embodiment is an apparatus for measuring a partial discharge inception voltage (PDIV: Partial Discharge Inception Voltage) or a repetitive partial discharge inception voltage (RPDIV: Repetitive Partial Discharge Inception Voltage) of the measured object 11. Note that the apparatus 1 for measuring a partial discharge inception voltage or extinction voltage may also be an apparatus for measuring a partial discharge extinction voltage (PDEV: Partial Discharge extinction voltage) or a repetitive partial discharge extinction voltage (RPDEV: Repetitive Partial Discharge extinction voltage).

[0012] An apparatus 1 for measuring a partial discharge inception voltage or a partial discharge extinction voltage comprises a power supply unit 2, first and second connection conductive paths 31 and 32, a voltage detection unit 4, and a processing device 5. As shown in FIGS. 2 to 6, the power supply unit 2 has first and second output terminals 21 and 22, and applies a voltage for measurement (hereinafter also referred to as "measurement voltage") to a measurement object 11. The first and second connection conductive paths 31 and 32 electrically connect the first and second output terminals 21 and 22 to first and second connection terminals 111 and 112, which are insulated from each other in the measurement object 11, respectively. As shown in FIG. 1, the voltage detection unit 4 detects a voltage applied between the first connection conductive path 31 and the second connection conductive path 32, and outputs the detection result to the processing device 5. The processing device 5 controls the operation of the power supply unit 2 and determines whether partial discharge occurs based on the detection result from the voltage detection unit 4.

[0013] The apparatus 1 for measuring a partial discharge inception voltage or a partial discharge extinction voltage according to the present embodiment is devised to suppress a situation in which partial discharge measurement at an assumed measurement voltage cannot be performed due to deformation of the waveform of the measurement voltage while the measurement voltage propagates through the first and second connection conductive paths 31 and 32. As will be described in detail later, in the apparatus 1 for measuring a partial discharge inception voltage or a partial discharge extinction voltage according to the present embodiment, the first and second connection conductive paths 31 and 32 each include a bus bar, a divided conductor, or a hollow wire, and have a length of 1 m or less, thereby suppressing deformation of the waveform of the measurement voltage caused by propagation through the first and second connection conductive paths 31 and 32. Hereinafter, each part of the apparatus 1 for measuring a partial discharge inception voltage or a partial discharge extinction voltage according to the present embodiment will be described in detail.

[0014] The power supply unit 2 outputs the measurement voltage from the first and second output terminals 21 and 22 to apply the measurement voltage to the measurement object 11. The measurement voltage preferably includes a high-frequency component (for example, 100 Hz or higher). When the measurement voltage contains a high-frequency component, the waveform of the measurement voltage is likely to be deformed by propagation through the two connection conductive paths, and thus the apparatus 1 for measuring a partial discharge inception voltage or a partial discharge extinction voltage according to the present embodiment, which can suppress deformation of the waveform of the measurement voltage, is suitably used. The measurement voltage can be, for example, an impulse voltage or an inverter surge pulse.

[0015] As shown in Figures 2 to 6, the first and second output terminals 21 and 22 are plate-shaped. As shown in Figures 3, 4, and 6, each of the first and second output terminals 21 and 22 has a through hole 20 for inserting a bolt B1. Also, as shown in Figures 3 and 4, a nut N1 for screwing the bolt B1 is placed on the back side of the portion of the power supply unit 2 where the through hole 20 of the first and second output terminals 21 and 22 is formed. The nut N1 is fixed to the power supply unit 2 so as not to rotate when the bolt B1 is screwed in.

[0016] As shown in Figure 3, the input end 301, which is one end of the first connecting conductive path 31, is superimposed on the first output terminal 21. The first output terminal 21 and the first connecting conductive path 31 are electrically connected by inserting a bolt B1 through the through hole 301a formed in the first connecting conductive path 31 and the through hole 20 in the first output terminal 21 and screwing the bolt B1 into a nut N1. As shown in Figure 4, the input end 301, which is one end of the second connecting conductive path 32, is superimposed on the second output terminal 22. The second output terminal 22 and the second connecting conductive path 32 are electrically connected by inserting a bolt B1 through the through hole 301a formed in the second connecting conductive path 32 and the through hole 20 in the second output terminal 22 and screwing the bolt B1 into a nut N1. The first and second output terminals 21 and 22 are not particularly limited, and various types of terminals can be used.

[0017] In this embodiment, the first and second connecting conductive paths 31 and 32 are designed so that the waveform of the measured voltage does not deform as the measured voltage propagates from the power supply unit 2 to the object under test 11.

[0018] Here, we will explain the theory of how the voltage waveform is deformed as the measured voltage propagates through the conductive path. It is known that when a surge voltage f(t) is applied to an infinitely long conductive path, the voltage e(x,t)[V] at a distance x[m] from the input end of the conductive path and a time t[μs] is expressed by the following equation (1). TIFF2026141535000002.tif16118

[0019] The symbol a[1 / m] in equation (1) is expressed in equation (2) below and is the attenuation constant considering the skin effect of the conductor in the conductive path. Also, the symbol v[m / μs] in equation (1) is expressed in equation (3) below and is the surge propagation speed. TIFF2026141535000003.tif23137TIFF2026141535000004.tif15137TIFF2026141535000005.tif17137TIFF2026141535000006.tif10137

[0020] Z in equation (4) C [Ω] is the surge impedance of the conductive path. In equation (5), R[Ω / m] is the line resistance of the conductive path, R0[Ω / m] is the DC resistance of the conductive path, σ[μs / rad] is the skin effect coefficient, and ω[rad / μs] is the angular frequency. Also, in equations (3) and (4), L[H / m] is the inductance per unit length of the object under test, and C[F / m] is the conductance per unit length of the object under test. That is, L and C are characteristics of the object under test. Furthermore, equations (1) and (2) to (5) show that the larger the skin effect coefficient σ and length x of the conductive path, the greater the contribution to voltage waveform distortion.

[0021] As explained above, the deformation of the measured voltage waveform is due to the skin effect coefficient σ and length x of the conductive path used. That is, the larger the skin effect coefficient of the conductive path, the greater the deformation of the measured voltage waveform, and the longer the length x of the conductive path, the greater the deformation of the measured voltage. As an example, as shown in Figure 7, numerical calculations were performed using equations (1) to (5) assuming that the skin effect coefficient σ of the conductive path is 1 and 100, respectively, and the waveforms of the impulse voltage were compared. In Figure 7, the result for the case where the skin effect coefficient σ of the conductive path is 1 is shown by a solid line, and the result for the case where it is 100 is shown by a dashed line. Also, in both examples in Figure 7, the length x of the conductive path was assumed to be 1. As can be seen from Figure 7, it can be seen that the voltage waveform is distorted when the skin effect coefficient σ of the conductive path is large.

[0022] Furthermore, as shown in Figure 8, numerical calculations were performed using equations (1) to (5) assuming the conductive path length x was 1m and 100m, respectively, and the waveforms of the impulse voltage were compared. In Figure 8, the results for the conductive path length x of 1m are shown by a solid line, and the results for the conductive path length x of 100m are shown by a dashed line. Also, in both examples in Figure 8, the skin effect coefficient σ of the conductive path was set to 1. As can be seen from Figure 8, it can be observed that there is a delay in voltage waveform propagation when the conductive path length x is long.

[0023] Considering the results in both Figures 7 and 8, it can be understood that as both the skin effect coefficient σ and the length x of the conductive path increase, the distortion of the voltage waveform increases further.

[0024] Considering the above, as shown in Figures 2 to 5, the first and second connecting conductive paths 31 and 32 in this embodiment have busbars, segmented conductors, or hollow wires, which tend to have a smaller skin effect coefficient σ compared to conventional coaxial cables. In this embodiment, each of the first and second connecting conductive paths 31 and 32 consists of a busbar. The busbar is formed from a highly conductive conductor such as copper in the shape of a long plate. Furthermore, each of the first and second connecting conductive paths 31 and 32 is formed to be short, with a length of 1 m or less.

[0025] As shown in Figure 3, the first connecting conductive path 31 is formed as a long, flat plate in one direction. The total length L1 of the first connecting conductive path 31 in the longitudinal direction is 1 m or less.

[0026] As shown in Figure 4, the second connecting conductive path 32 has a crank-shaped plate form. The second connecting conductive path 32 comprises a first portion 321 which is connected to the second output terminal 22 and is elongated in one direction, a second portion 322 which extends in the thickness direction of the first portion 321 from the end of the first portion 321 on the side of the object to be measured 11, and a third portion 323 which extends toward the object to be measured 11 from the end of the second portion 322 opposite to the first portion 321. In this embodiment, as will be described later, the height positions of the first connection terminal 111 of the object to be measured 11 connected to the first connecting conductive path 31 and the second connection terminal 112 of the object to be measured 11 connected to the second connecting conductive path 32 are different. Therefore, the second connecting conductive path 32 is formed in a crank shape to shift the positions of both ends of the second connecting conductive path 32 in the height direction. The shapes of the first and second connecting conductive paths 31 and 32 are not particularly limited and can be appropriately determined, for example, depending on the positional relationship between the first and second output terminals 21 and 22 of the power supply unit 2 and the first and second connecting terminals 111 and 112 of the object under test 11.

[0027] When a connecting conductive path has a bent shape, such as the second connecting conductive path 32, saying that the length of the connecting conductive path is 1m or less means that the total length of the connecting conductive path along the direction of conduction is 1m or less. For example, as shown in Figure 4, saying that the length of the second connecting conductive path 32 is 1m or less means that the sum of the lengths L21 of the first part 321, L22 of the second part 322, and L23 of the third part 323 is 1m or less.

[0028] The object to be measured 11 is electrically connected to the output end 302 of the first connecting conductive path 31, which is the end opposite to the input end 301, and to the output end 302 of the second connecting conductive path 32, which is the end opposite to the input end 301.

[0029] The object to be measured 11 is not particularly limited, but in this embodiment, as shown in Figure 5, it is a so-called arrow pair. The arrow pair comprises two enameled wires 110 that are electrically insulated from each other, a first connection terminal 111 electrically connected to one of the enameled wires 110, and a second connection terminal 112 electrically connected to the other enameled wire 110.

[0030] The enameled wire 110 comprises a rectangular conductor portion 110a having a substantially rectangular cross-sectional shape, and an electrically insulating coating 110b covering the conductor portion 110a. The two enameled wires 110 have a back-to-back portion 110c that overlaps each other in the thickness direction, and a curved portion 110d formed on both sides of the back-to-back portion 110c and curved in a direction away from each other. The back-to-back portion 110c of the two enameled wires 110 is fixed using, for example, a clip, wire, or other fixing member (not shown).

[0031] The coating 110b has been removed from both ends of the enameled wire 110, exposing the conductor portion 110a. A first connecting terminal 111 is electrically connected to the exposed conductor portion 110a of one enameled wire 110, and a second connecting terminal 112 is electrically connected to the exposed conductor portion 110a of the other enameled wire 110. As a result, the first connecting terminal 111 and the second connecting terminal 112 are at different height positions (i.e., positions in the overlapping direction of the enameled wires 110). In this embodiment, the first connecting terminal 111 and the second connecting terminal 112 are shown as being located at opposite ends of the two enameled wires 110, but they may also be located at the same end of the two enameled wires 110.

[0032] As shown in Figures 5 and 6, the first and second connecting terminals 111 and 112 are crimp terminals. Each of the first and second connecting terminals 111 and 112 comprises a crimped portion 101 crimped to the exposed conductor portion 110a of the enameled wire 110, and a plate-shaped tongue portion 102 extending from the crimped portion 101. The tongue portion 102 has a through hole 102a formed therein for inserting a bolt B2. The tongue portion 102 of the first connecting terminal 111 and the output end portion 302 of the first connecting conductive path 31 are superimposed, and the bolt B2 is inserted into the through hole 102a of the tongue portion 102 and the through hole 302a formed in the output end portion 302, and a nut N2 is screwed onto the bolt B2, thereby electrically connecting the first connecting terminal 111 and the first connecting conductive path 31. Similarly, the tongue portion 102 of the second connection terminal 112 and the output end portion 302 of the second connection conductive path 32 are overlapped, and the bolt B2 is inserted into the through hole 102a of the tongue portion 102 and the through hole 302a formed in the output end portion 302, and a nut N2 is screwed onto the bolt B2, thereby electrically connecting the second connection terminal 112 and the second connection conductive path 32.

[0033] In this embodiment, an arrow pair is shown as an example of the object to be measured 11, but the object to be measured 11 is not limited to an arrow pair; any object whose electrical insulation properties are to be evaluated can be used. For example, multiple windings of a three-phase induction motor equipped with U-phase windings, V-phase windings, and V-phase windings may be used as the object to be measured. Also, in this embodiment, the first and second connection terminals 111 and 112 of the object to be measured 11 are crimp terminals, but this is not limited to this. For example, the first and second connection conductive paths 31 and 32 may be directly connected to the exposed conductor portion 110a of the arrow pair as the object to be measured 11 using solder or the like, in which case crimp terminals are unnecessary, and the exposed portion which is part of the conductor portion 110a becomes the first and second connection terminals 111 and 112.

[0034] As shown in Figure 1, the voltage detection unit 4 detects the voltage value between the first connecting conductive path 31 and the second connecting conductive path 32 and outputs it to the processing unit 5.

[0035] The processing unit 5 comprises a processor and a control area including RAM, which serves as the calculation area during processor operation, and a storage unit that stores programs executed by the CPU, etc., which includes ROM, a hard disk, etc. The processing unit 5 is not limited to software-based implementation, as long as it is configured to realize its functions. For example, at least a portion of the functions of the processing unit 5 may be implemented using hardware such as logic circuits.

[0036] The processing unit 5 controls the operation of the power supply unit 2, causing the power supply unit 2 to output a voltage of a predetermined waveform to the object under test 11, and analyzes the output result of the voltage detection unit 4 when the measurement voltage is applied to the object under test 11 to detect the occurrence of partial discharge to the object under test 11. For example, the processing unit 5 sequentially applies multiple types of impulse voltages with different peak voltages to the object under test 11 so that the peak voltages gradually increase. Here, each type of impulse voltage is applied to the object under test 11 multiple times. The processing unit 5 then defines the peak voltage of the impulse voltage when partial discharge is detected for the first time or after a predetermined number of repetitions as the partial discharge initiation voltage (PDIV) or repeated partial discharge initiation voltage (RPDIV). The measurement of partial discharge can be performed, for example, by analyzing the results of the voltage detection unit 4, similar to the method described in the aforementioned Patent Document 1.

[0037] Furthermore, the method for measuring the partial discharge initiation voltage or the repeated partial discharge initiation voltage is not limited to the method described above, and known methods may be used. For example, the occurrence of partial discharge may be determined by detecting the current flowing through the first or second connecting conductive paths 31 and 32 due to the occurrence of partial discharge using a CT (Current Transformer). Alternatively, the occurrence of partial discharge may be determined by detecting electromagnetic waves generated due to the occurrence of partial discharge using an antenna.

[0038] (Operation and effects of the first embodiment) In the apparatus 1 for measuring the initiation voltage or extinction voltage of partial discharge according to this embodiment, each of the first and second connecting conductive paths 31 and 32 has a busbar and a length of 1 m or less. By configuring each of the first and second connecting conductive paths 31 and 32 using a busbar with a small skin effect, and by making the length of each of the first and second connecting conductive paths 31 and 32 1 m or less, deformation of the voltage waveform caused by the voltage for measurement passing through the first and second connecting conductive paths 31 and 32 is suppressed.

[0039] Furthermore, each of the first and second connecting conductive paths 31 and 32 has a busbar. Therefore, the work of connecting each of the first and second connecting conductive paths 31 and 32 to the power supply unit 2 and the object to be measured 11 becomes easier.

[0040] As described above, this embodiment provides a device for measuring the initiation voltage or extinction voltage of a partial discharge that can suppress deformation of the voltage waveform caused by the voltage for measurement passing through the connecting conductive path from the power supply to the object under test.

[0041] [Second Embodiment] A second embodiment of the present invention will be described with reference to Figure 9. Figure 9 is a plan view of the measuring device 1 and the object to be measured 11 for measuring the starting voltage or extinction voltage of partial discharge in this embodiment.

[0042] This embodiment is similar in basic configuration to the first embodiment, but the busbars constituting the first and second connecting conductive paths 31 and 32 each have a rotatable busbar 303 that can rotate relative to the power supply unit 2. In this embodiment, the first and second connecting conductive paths 31 and 32 each have a rotatable busbar 303. The first and second connecting conductive paths 31 and 32 can rotate relative to the power supply unit 2 by loosening the bolt B1.

[0043] Here, we assume that the reference position is when the first and second connecting conductive paths 31 and 32 are mounted in a direction perpendicular to both the alignment direction of the first output terminal 21 and the second output terminal 22, and the thickness direction of the first connecting conductive path 31 (i.e., the left-right direction in Figure 9). In Figure 9, the first connecting conductive path 31 is fixed in a position rotated by a predetermined angle from the reference position shown by the dashed line. This adjusts the distance between the output end 302 of the first connecting conductive path 31 and the output end 302 of the second connecting conductive path 32 to match the distance between the first connecting terminal 111 and the second connecting terminal 112 on the object under measurement 11.

[0044] In this embodiment, only the first connecting conductive path 31 is rotated from its reference position, but the second connecting conductive path 32 may also be rotated from its reference position.

[0045] The other configurations of this embodiment are the same as those of the first embodiment. In addition, among the reference numerals used in the second embodiment and subsequent embodiments, those that are the same as those used in the previously described embodiments represent the same components, etc., as those in the previously described embodiments, unless otherwise specified.

[0046] (Operation and effects of the second embodiment) In this embodiment, the busbars constituting the first and second connecting conductive paths 31 and 32 each have a rotatable busbar 303 that can rotate relative to the power supply unit 2. Therefore, by appropriately rotating the rotatable busbar 303 relative to the power supply unit 2, the distance between the output end 302 of the first connecting conductive path 31 and the output end 302 of the second connecting conductive path 32 can be adjusted. As a result, in this embodiment, it becomes easier to connect various objects to be measured that have different distances between the first connection terminal 111 and the second connection terminal 112. Furthermore, it has the same functions and effects as the first embodiment.

[0047] [Third Embodiment] A third embodiment of the present invention will be described with reference to Figure 10. Figure 10 is a plan view of the measuring device 1 and the object to be measured 11 for measuring the starting voltage or extinction voltage of partial discharge in this embodiment.

[0048] This embodiment, like the second embodiment, is an example in which the busbars constituting the first and second connecting conductive paths 31 and 32 each have a rotatable busbar 303a that is rotatable relative to the power supply unit 2. In this embodiment, each of the first and second connecting conductive paths 31 and 32 has a reference busbar 304 attached to the power supply unit 2 and a rotatable busbar 303a that is rotatably attached to the reference busbar 304.

[0049] The reference busbar 304 of the first connecting conductive path 31 has the same configuration as the first connecting conductive path in the first embodiment (see, for example, reference numeral 31 in Figures 2 and 3). The reference busbar 304 of the second connecting conductive path 32 has the same configuration as the second connecting conductive path in the first embodiment (see, for example, reference numeral 32 in Figures 2 and 4).

[0050] The rotating busbar 303a is formed as a long plate in one direction. One end of the rotating busbar 303a is superimposed on the output end 304a of the reference busbar 304, which is the end opposite to the power supply unit 2. The rotating busbar 303a and the reference busbar 304 are rotatably attached to each other by bolt B3 passing through them and a nut (not shown) screwed onto bolt B3. That is, by loosening bolt B3, the rotating busbar 303a can rotate relative to the reference busbar 304 and the power supply unit 2. In addition, the output end 305a of the rotating busbar 303a, which is the end opposite to the side connected to the reference busbar 304, is fixed to each other by bolt B4 passing through them and a nut (not shown) screwed onto bolt B4.

[0051] Here, we assume that the reference position is when the rotating busbar 303a is mounted in a direction perpendicular to both the alignment direction of the first output terminal 21 and the second output terminal 22, and the thickness direction of the first connecting conductive path 31 (i.e., the left-right direction in Figure 10). In Figure 10, the rotating busbars 303a of the first and second connecting conductive paths 31 and 32 are fixed in a position rotated by a predetermined angle away from each other from the reference position shown by the dashed line. This adjusts the distance between the output end 305a of the rotating busbars 303a of the first and second connecting conductive paths 31 and 32 to match the distance between the first connecting terminal 111 and the second connecting terminal 112 on the object under measurement 11. Otherwise, the configuration is the same as that of the first and second embodiments.

[0052] (Operation and Effects of the Third Embodiment) This embodiment also has the same functions and effects as the first and second embodiments.

[0053] [Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to Figures 11 and 12. Figure 11 is a plan view of the hollow busbar in this embodiment. Figure 12 is a side view of the hollow busbar in this embodiment.

[0054] This embodiment is a modification of the first embodiment in which the busbars constituting the first and second connecting conductive paths 31 and 32 are replaced with hollow busbars. Each of the first and second connecting conductive paths 31 and 32 is formed by overlapping two divided busbars 305. Each of the first and second connecting conductive paths 31 and 32 has an overlapping portion 306 at both ends where the two divided busbars 305 overlap, and a hollow portion 307 in the center where the two busbars are separated. Each of the first and second connecting conductive paths 31 and 32 can be connected to the object to be connected using bolts or the like at the overlapping portion 306. Otherwise, it is the same as in the first embodiment.

[0055] (Operation and effects of the fourth embodiment) In this embodiment, the busbars constituting the first and second connecting conductive paths 31 and 32 are hollow busbars. Because hollow busbars have a hollow portion 307, it is easier to secure a surface area and reduce the skin effect. Therefore, in this embodiment, the deformation of the voltage waveform caused by the voltage for measurement passing through the first and second connecting conductive paths 31 and 32 can be further suppressed. Furthermore, it has the same functions and effects as the first embodiment.

[0056] [Fifth Embodiment] A fifth embodiment of the present invention will be described with reference to Figures 13 and 14. Figure 13 is a cross-sectional view along the longitudinal direction of the hollow wire 308 in this embodiment. Figure 14 is a cross-sectional view perpendicular to the longitudinal direction of the hollow wire 308.

[0057] This embodiment is a modification of the first embodiment in which the busbars constituting the first and second connecting conductive paths 31 and 32 are replaced with hollow wires 308. The hollow wire 308 consists of a cylindrical conductor. In this embodiment, the hollow wire 308 has a rectangular annular cross-section. The method of connecting the hollow wire 308 to the power supply unit 2 is not particularly limited, but for example, a crimp terminal may be attached to one end of the hollow wire 308 and the hollow wire 308 and the power supply unit 2 may be connected via the crimp terminal. The same applies to the method of connecting the hollow wire 308 to the object to be measured 11. Otherwise, it is the same as in the first embodiment.

[0058] (Operation and effects of the fifth embodiment) In this embodiment, the busbars constituting the first and second connecting conductive paths 31 and 32 are hollow wires 308. Because the hollow wires 308 have a hollow portion, it is easier to secure a surface area and reduce the skin effect. Therefore, in this embodiment, the deformation of the voltage waveform caused by the voltage for measurement passing through the first and second connecting conductive paths 31 and 32 can be further suppressed. Furthermore, it has the same functions and effects as the first embodiment.

[0059] [Sixth Embodiment] A sixth embodiment of the present invention will be described with reference to Figures 15 and 16. Figure 15 is a plan view of the measuring device 1 and the object to be measured 11 for measuring the starting voltage or extinction voltage of partial discharge in this embodiment. Figure 16 is a cross-sectional view perpendicular to the longitudinal direction of the Litz wire 309.

[0060] This embodiment is a modified version of the first embodiment, with changes to the configurations of the first and second connecting conductive paths 31 and 32. Specifically, the first and second connecting conductive paths 31 and 32 are equipped with segmented conductors. A segmented conductor is made up of multiple insulated wires having a conductor and an insulating film covering the conductor. In this embodiment, a Litz wire 309 is used as the segmented conductor. As shown in Figure 16, the Litz wire 309 is made up of multiple strands 309a made of conductors and insulated wires 309c made of an electrically insulating coating 309b covering the strands 309a, twisted together. As shown in Figure 15, crimp terminals 30 are attached to both ends of the Litz wire 309, and the connection between the Litz wire 309 and the power supply unit 2 and the object to be measured 11 is made via the crimp terminals 30. Otherwise, it is the same as in the first embodiment.

[0061] (Operation and Effects of the Sixth Embodiment) In this embodiment, each of the first and second connecting conductive paths 31 and 32 is equipped with a divided conductor. A divided conductor is made up of multiple insulated wires bundled together, and because the current is divided and flows through multiple insulated wires, the skin effect is easily reduced. Therefore, in this embodiment, the deformation of the voltage waveform caused by the voltage for measurement passing through the first and second connecting conductive paths 31 and 32 can be further suppressed.

[0062] Furthermore, in this embodiment, the divided conductor is a Litz wire 309. Because the Litz wire 309 has high flexibility, it is easy to connect to objects to be measured 11 of various sizes. Furthermore, it has the same functions and effects as the first embodiment.

[0063] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0064] [1] A device 1 for measuring the initiation voltage or extinction voltage of a partial discharge of an object 11 to be measured, comprising: a power supply unit 2 that outputs a voltage for the measurement; and a plurality of connecting conductive paths 31, 32 that electrically connect a plurality of output terminals 21, 22 of the power supply unit 2 to a plurality of connection terminals 111, 112 of the object 11 to be measured, wherein the plurality of connecting conductive paths 31, 32 have busbars, divided conductors or hollow conductors and have a length of 1 m or less, the device 1 for measuring the initiation voltage or extinction voltage of a partial discharge.

[0065] [2] The device for measuring the initiation voltage or extinction voltage of a partial discharge according to [1], wherein at least one of the plurality of connecting conductive paths 31, 32 has the busbar.

[0066] [3] The busbar is a hollow busbar, as described in [2], for measuring the starting voltage or extinction voltage of a partial discharge.

[0067] [4] The busbar is a rotating busbar 303, 303a that is rotatable relative to the power supply unit 2, the partial discharge start voltage or extinction voltage measuring device 1 according to [2] or [3].

[0068] [5] A measuring device 1 for measuring the initiation voltage or extinction voltage of a partial discharge according to any one of [1] to [4], wherein each of the plurality of connecting conductive paths 31, 32 has a Litz wire 309 as the divided conductor.

[0069] (Note) Although embodiments of the present invention have been described above, the embodiments described herein do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Moreover, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of Symbols]

[0070] 1. A device for measuring the onset voltage or extinction voltage of partial discharge. 11…Object to be measured 111...First connection terminal 112...Second connection terminal 2…Power supply section 21…First output terminal 22...Second output terminal 303,303a... Rotating busbar 309... The Ritz Line 31…First connecting conductive path 32...Second connecting conductive path

Claims

1. A device for measuring the onset voltage or extinction voltage of partial discharge of an object under test, A power supply unit that outputs the voltage for the measurement, The power supply unit comprises multiple output terminals and the object under test comprises multiple connecting conductive paths that electrically connect to each other, The aforementioned plurality of connecting conductive paths have busbars, divided conductors, or hollow conductors, and have a length of 1 m or less. A device for measuring the onset voltage or extinction voltage of partial discharge.

2. At least one of the plurality of connecting conductive paths has the busbar, The apparatus for measuring the starting voltage or extinction voltage of partial discharge according to claim 1.

3. The aforementioned bus bar is a hollow bus bar. The device for measuring the starting voltage or extinction voltage of a partial discharge according to claim 2.

4. The busbar has a rotating busbar that is rotatable relative to the power supply unit. The device for measuring the starting voltage or extinction voltage of a partial discharge according to claim 2.

5. Each of the plurality of connecting conductive paths has a Litz wire as the dividing conductor. The apparatus for measuring the starting voltage or extinction voltage of partial discharge according to claim 1.

Images