JP2002062330A - Apparatus and method for evaluating integrity of insulation between coil turns - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate integrity of inter-coil turns between insulation layers high sensitivity in a dynamo-electric machine, such as an electric motor having a winding comprising a plurality of turns of coil. SOLUTION: In the dynamo-electric machine, having a winding comprising a plurality of turns of coils, it is arranged so to include a power source unit (an inverter driver 11) for generating a surge voltage 4, a partial charge detection means 2 (through-type high-frequency current transformer 12) for detecting partial charge in an inter-turn insulation layers and a measurement judging means 3 for evaluating the value of the detected partial discharge. The surge voltage is applied to a circuit line side terminal of the winding, to generate a partial charge in the inter-turn insulation layer by a high voltage produced between the turns of coil near the circuit line side of the winding and the relation is measured between the value of the detected partial charge, the magnitude of the surge voltage and the steepness of the rising part thereof. Thus, the partial charge in the inter-turn insulation layer is judged being distinguished from the partial charge in the insulation layer to the ground of the coil from the relation obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating electric machine such as a motor having a winding composed of coils having a plurality of turns, and more particularly to an insulation between coil turns for evaluating the soundness of an insulation layer between the turns. The present invention relates to a soundness evaluation device and method.

[0002]

2. Description of the Related Art When a surge voltage is applied to a rotating electric machine winding composed of coils having a plurality of turns, most of the voltage is applied between turns of a line side coil. Therefore,
The insulation layer between turns of the line-side coil of a winding to which a large number of surge voltages are applied, such as a winding of a high-voltage rotating electric machine driven by an inverter, is not only thermally deteriorated, but also significantly deteriorates due to voltage. Eventually, a dielectric breakdown accident may occur. If the soundness of such an inter-turn insulating layer can be evaluated, it is possible to conserve it before an accident. Conventionally, an apparatus for evaluating the soundness of an inter-turn insulating layer has been disclosed in
There is an apparatus as described in Japanese Patent No. 257862. However, in this conventional device, a pulse voltage for generating a voltage between turns is directly applied to a winding of a phase to be diagnosed, and a partial discharge current generated only between turns near a pulse voltage application terminal of the winding is applied. The measurement was performed at the terminals of the windings of the other phase far away from the position where the occurrence occurred. Further, a circuit for allowing the partial discharge current to flow through the detection unit is not particularly provided. Therefore, there is a problem that the detection sensitivity of the partial discharge current is extremely low. On the other hand, as another device for evaluating the soundness of the inter-turn insulating layer, there is a device for applying a surge voltage to the winding and evaluating the degree of distortion of the voltage waveform, but in this device, the inter-turn insulating layer is insulated. There has been a problem that the failure cannot be detected unless the failure is a serious failure such as destruction.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to evaluate the soundness of an insulation layer between coil turns with high sensitivity in a rotating electric machine such as a motor having a winding composed of a plurality of turns. It is in.

[0004]

In order to solve the above-mentioned problems, in a rotating electrical machine having a winding composed of a coil having a plurality of turns, a power supply device for generating a surge voltage and a portion of an inter-turn insulating layer are provided. A partial discharge detection means for detecting discharge, and a measurement determination means for evaluating the detected partial discharge amount, applying a surge voltage to the line side terminal of the winding,
A high voltage is generated between turns of the coil close to the line side of the winding to generate a partial discharge in the inter-turn insulating layer, and the detected partial discharge amount and the magnitude of the surge voltage and the steepness of the rising portion thereof The relationship is measured, and the partial discharge of the inter-turn insulating layer is distinguished from the partial discharge of the other insulating layer based on the relationship.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the apparatus and method for evaluating insulation integrity between coil turns according to the present invention. This embodiment is an example applied to a motor device driven by an inverter device. In FIG. 1, reference numeral 11 denotes an inverter driving device, which also functions as a power supply device 1 for generating a surge voltage 4 for measurement. Inverter driving device 1 also serving as power supply device 1
Reference numeral 1 denotes a configuration in which a voltage Vp and a surge voltage for measurement in which the steepness dV / dt of a rising portion is changed can be applied to an arbitrary two-phase winding of the electric motor 6. The discharge detection unit 2 is disposed between the power supply device 1 and the electric motor 6. The discharge detector 2 is constituted by a through-type high-frequency current transformer 12. The output of the high-frequency current transformer 12 is input to the measurement determination circuit 3. The inverter driving device 11 outputs a predetermined controlled voltage during operation to drive the electric motor 6. At a predetermined timing or at the time of input of a manual measurement start signal, a predetermined two-phase winding to be diagnosed of the electric motor 6 is connected to the electric motor 6 via the drive cable 13 with a polarity opposite to the ground potential of the electric motor 6 as shown in FIG. A surge voltage for measurement having a symmetrical waveform is applied, and the remaining one-phase winding is kept at the ground potential of the electric motor 6 or at a certain level of potential. The current flowing through the winding of each phase of the motor 6 when the surge voltage is applied mainly consists of the charging current of the capacitance formed by the winding insulating layer, but the capacitance formed by the winding insulating layer is Since the windings are substantially equal, the charging currents of the capacitances formed by the winding insulating layers due to the positive and negative polarities of the measuring surge voltages applied to the predetermined two-phase windings have the same value in opposite polarities. Therefore, the charging current is canceled and is not output to the output of the feedthrough type high-frequency current transformer 12 in which the cables to the windings of the respective phases pass in the same direction. That is, the penetration type high-frequency current transformer 1
Reference numeral 2 also serves as a charge current cancel circuit. On the other hand, by applying the surge voltage, a high voltage is applied to the coil-to-ground insulating layer of the winding to be diagnosed, and a high voltage is also applied to the inter-turn insulating layer. When this voltage level becomes higher than a certain level, partial discharge occurs in these insulating layers. Part of the current due to this partial discharge becomes a pulse, and the drive power cable 1
Propagate 3. When the drive power cable 13 connecting the inverter drive device 11 and the motor 6 has a sheath,
The ground wire 23 of the sheath is arranged so as not to penetrate the high-frequency current transformer 12. Therefore, the partial discharge current pulse generated inside the motor and propagated to the drive cable 13 returns through the ground wire 23 that does not penetrate the through-type high-frequency current transformer 12, and the partial discharge current pulse Pulses can be detected. If there is no sheath, the partial discharge current pulse propagated to the drive cable 13 will be fed back through the ground circuit of the inverter drive device 11, and the through discharge high-frequency current transformer 12 can similarly detect the partial discharge pulse. . In the output of the through-type high-frequency current transformer 12, since the large charging current of the winding insulating layer is canceled, the measurement determination circuit 3 can amplify only the partial discharge current pulse in a predetermined frequency range.

The magnitude of the partial discharge, that is, the amount of partial discharge Q is measured by a method of comparing the amplified value with a value previously measured by a simulated partial discharge current pulse. The partial discharge amount Q is equal to the surge voltage Vp as indicated by the solid line 31 in FIG.
Increases with increasing. A threshold value Qs of a constant discharge amount was determined, and a voltage Vps of a surge voltage when a partial discharge amount of the threshold value Qs was generated was obtained. Even with the surge voltage of the same voltage Vp, the steepness dV /
When dt increases, the voltage applied to the inter-turn insulating layer near the line side of the winding increases, so that the steepness d of the rising portion increases.
The relationship between the voltage Vp and the partial discharge amount Q with respect to a surge voltage having a large V / dt is as shown by a two-dot chain line 32 in FIG. That is, the voltage Vps of the surge voltage that generates the partial discharge amount of the threshold value Qs in the case of the two-dot chain line 32 is smaller than Vps in the case of the solid line 31. Here, FIG. 2 shows the relationship between the surge voltage and the amount of partial discharge, and 31 shows the relationship between the voltage Vp of the surge voltage and the amount of partial discharge Q (the steepness dV of the rising portion) in the partial discharge in the inter-turn insulating layer. / Dt is 3
Reference numeral 32 denotes the relationship between the voltage Vp of the surge voltage and the amount of partial discharge Q (when the steepness dV / dt of the rising portion is larger than 31) in the partial discharge in the inter-turn insulating layer.

Therefore, the relationship between the voltage Vps of the surge voltage that generates the partial discharge amount of the threshold value Qs and the steepness dV / dt of the rising portion of the surge voltage is shown as follows.
As shown by the solid line 36 in FIG. 3, as the steepness dV / dt of the rising portion of the surge voltage increases, the voltage Vps of the surge voltage that causes the partial discharge amount of the threshold value Qs decreases. On the other hand, in the case of the ground insulating layer of the coil, the voltage applied to the ground insulating layer is constant even if the steepness dV / dt of the surge voltage changes. Also, the partial discharge amount is constant without depending on the steepness dV / dt of the surge voltage up to a high region around 1 KV / μs. In a high region of 1 KV / μs or more, the steepness dV /
As dt increases, partial discharge of the insulating layer becomes less likely to occur. In other words, above this region, the higher the steepness dV / dt of the rising portion of the surge voltage, the smaller the partial discharge amount Q for the same surge voltage Vp, so that a partial discharge amount with a constant threshold value Qs is generated. The voltage Vps of the surge voltage slightly increases as the steepness dV / dt of the rising portion increases. Accordingly, when a partial discharge has occurred in the ground insulating layer of the coil, the relationship between the steepness dV / dt of the rising portion of the surge voltage and the voltage Vps of the surge voltage that generates the partial discharge having the threshold value Qs is shown by a solid line in FIG. 38, the voltage Vps of the surge voltage that generates the partial discharge of the threshold value Qs is constant with respect to the steepness dV / dt of the rising portion of the surge voltage, and the steepness dV / dt of the rising portion of the surge voltage is constant. It is slightly higher in a fairly large area. FIG. 3 shows the relationship between the voltage Vps of the surge voltage for determining the partial discharge of the inter-turn insulating layer and the steepness dV / dt of the rising portion, and FIG. 4 shows the surge for determining the partial discharge of the coil-to-ground insulating layer. There is a relationship between the voltage Vps of the voltage and the steepness dV / dt of the rising portion, and the voltage Vps of the surge voltage and the steepness of the rising portion which generate the partial discharge with the constant threshold value Qs as shown in FIGS. From the relationship of the degree dV / dt, it can be determined whether the discharge is occurring in the inter-turn insulating layer or the coil-to-ground insulating layer. The measurement determination circuit 3 determines the partial discharge of the inter-turn insulating layer based on the relationship described above, and the relationship becomes as shown by a dashed line 37 in FIG. If the voltage condition is equal to or lower than a level in which a certain margin is taken into consideration, a determination is made that repair is required. Here, in FIG. 3, reference numeral 30 denotes a voltage level applied to the inter-turn insulating layer at the time of use in consideration of a certain margin, and reference numeral 35 denotes a threshold value Qs of a constant discharge amount in partial discharge in the inter-turn insulating layer. Surge voltage Vp reached
And the steepness dV / dt of the rising portion (measured value),
36 is a relationship between a surge voltage Vp reaching a threshold value Qs of a constant discharge amount and a steepness dV / dt of a rising portion in a partial discharge in the inter-turn insulating layer (measured value approximation line), and 37 is an inter-turn insulating layer. Relationship between the surge voltage Vp reaching the threshold value Qs of a constant discharge amount and the steepness dV / dt of the rising portion in the partial discharge (state in which the degree of insulation is reduced)
(Repair level). Also, in FIG.
Is a relationship (measured value) between a surge voltage Vp reaching a threshold value Qs of a fixed discharge amount and a steepness dV / dt of a rising portion in a partial discharge in the coil-to-ground insulating layer, and 39 is a partial discharge in the coil-to-ground insulating layer. 5 shows a relationship (measured value approximation line) between a surge voltage Vps reaching a threshold value Qs of a constant discharge amount and a steepness dV / dt of a rising portion. In the present embodiment, the threshold value Qs is set to 1000 pC, and the margin is doubled.

In this embodiment, a surge voltage is applied to the two-phase winding in order to cancel the charging current of the capacitance formed by the coil insulating layer of the winding. It will be evaluated by the combination of phases. Therefore, the soundness of each phase cannot be evaluated separately. However, for example, when the phases are A, B, and C, and the partial discharge amount of the A phase is the largest, in the measurement results of A and B, B and C, and C and A, A and B and A and Since the partial discharge amount in the case of combining C is larger than the partial discharge amount in the case of combining B and C, the phase having the largest partial discharge amount, that is, the phase having the least sound can be determined. Generally,
In many cases, the insulation thickness of the coil-to-ground insulation layer is larger than that of the inter-turn insulation layer, and partial discharge in the inter-turn insulation layer is mainly performed. Therefore, Vps is measured at a surge voltage at which the steepness dV / dt of the rising portion is the same as in use, and Vps is measured.
The same effect can be obtained by a simple method of determining the necessity of repair by comparing the voltage condition at the time of use with a level in which a certain degree of tolerance is taken into consideration. Further, even when it is determined that the motor device needs repair, the steepness dV / dt of the rising portion of the surge voltage generated during the operation of the inverter drive device 11.
If the operation can be performed with a small value, the level in consideration of a certain margin in the voltage condition applied during use during the turn indicated by the mark x in FIG. 3 will move to a position where dV / dt is small. It is possible to continue the operation. In the present embodiment, it is possible to apply a surge voltage for measurement instantaneously even during operation of the motor device and perform measurement, but generally, the same wiring as during operation while the motor is stopped is used.
Without any changes, the soundness of the coil turn insulation is evaluated.

FIG. 5 shows another embodiment of the present invention. 1
Is a power supply device capable of generating a surge voltage for measurement. The partial discharge detection unit 2 is arranged between the power supply device 1 and the electric motor 6. The partial discharge detector 2 is constituted by a through-type high-frequency current transformer 12, and outputs the output of the high-frequency current transformer 12 to a measurement determination circuit 3. The power supply device 1 applies a measurement surge voltage in which the voltage Vp and the steepness dV / dt of the rising portion are changed to arbitrary two-phase windings of the electric motor 6. The connection lines 25 from the power supply device 1 to the respective phase windings are made to pass through the through-type high-frequency current transformer 12 in opposite directions. The current flowing through each phase winding of the electric motor 6 when the measurement surge voltage is applied mainly consists of a charging current of the capacitance formed by the winding insulating layer, but the capacitance formed by the winding insulating layer is: Since the windings of each phase are substantially equal, the charging currents of the capacitance formed by the winding insulating layer due to the measurement surge voltage applied to the predetermined two-phase windings are opposite to each other in the feedthrough type high frequency current transformer 12. It flows in the direction and is canceled. That is, the feedthrough type high frequency current transformer 12 also functions as a charge current cancel circuit. On the other hand, by applying the surge voltage, a high voltage is applied to the coil insulating layer of the winding, and a high voltage is applied between turns. If this level exceeds a certain level, discharge occurs in these insulating layers. A part of the current due to the partial discharge becomes a pulse and propagates through the connection line 25 from the power supply device 1 to the winding of each phase. The current pulse due to the partial discharge propagating through the connection line 25 returns to the grounding circuit of the power supply 1. If the impedance of the grounding circuit is large, the measurement sensitivity is reduced. , A feedback coupling capacitor 24 is disposed. Thus, the current pulse of the partial discharge can be detected by the through-type high-frequency current transformer 12. This through-type high-frequency current transformer 12
Since the large charge current of the winding insulating layer is canceled in the output of (3), the measurement determination circuit 3 can amplify only the partial discharge current pulse in the predetermined frequency range.

Hereinafter, as in the embodiment of FIG. 1, the magnitude of the partial discharge, that is, the partial discharge amount Q is measured by a method of comparing the amplified value with a value measured in advance by a simulated partial discharge current pulse. . Then, based on the relationship between the measured partial discharge amount Q, the applied voltage Vp of the surge voltage, and the steepness dV / dt of the rising portion of the surge voltage, as shown in FIG. 3, the surge voltage reaching the threshold value Qs of the constant discharge amount is obtained. V
The relationship dV / dt between ps and the rise time is determined. In the present embodiment, the threshold value Qs is set to 1000 pC. The measurement determination circuit 3 determines that this relationship is a partial discharge of the inter-turn insulating layer from the above-described characteristics, and
If this relationship is as shown by the dashed line 37 in FIG. 3 and is equal to or less than the level indicated by the crosses, taking into account a certain margin for the voltage condition applied between turns during use, a determination is made as to whether a repair is required. To In the present embodiment, twice is considered as the margin.

Also in this embodiment, as described in the embodiment of FIG. 1, the phase having the largest partial discharge amount, that is, the phase having the least sound can be determined. Further, the surge voltage Vps reaching the threshold value Qs of a constant discharge amount and the steepness dV /
From the relationship of dt, it can be determined which of the inter-turn insulating layer and the coil-to-ground insulating layer is discharging.

[0012]

As described above, according to the present invention,
In a rotating electric machine such as an electric motor having a winding composed of a plurality of turns of a coil, a partial discharge of an insulating layer between turns is determined separately from a partial discharge of another insulating layer (coil-to-ground insulating layer). The soundness of the inter-turn insulating layer can be evaluated with high sensitivity, and the destruction of the inter-turn insulating layer of the rotating electric machine can be prevented beforehand, and the reliability of the rotating electric machine device can be improved.

[Brief description of the drawings]

FIG. 1 is an embodiment of a device for evaluating insulation integrity between coil turns according to the present invention.

FIG. 2 is a diagram showing a relationship between a surge voltage and a partial discharge amount.

FIG. 3 is a diagram illustrating a method for evaluating insulation integrity between coil turns according to the present invention.

FIG. 4 is a diagram for explaining a method for distinguishing partial discharges of a coil-to-ground insulating layer by the method of evaluating insulation integrity between coil turns according to the present invention.

FIG. 5 shows another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power supply device, 2 ... Partial discharge detection part, 3 ... Measurement judgment circuit, 4 ... Surge voltage for measurement, 6 ... Rotating electric machine, 11 ... Inverter drive device, 12 ... Through-type high frequency current transformer, 13 ... Drive cable, 23 ... drive cable sheath ground wire, 24 ...
Coupling capacitor, 25 ... Connection for applying surge voltage for measurement

Claims (9)

[Claims] In a rotating electrical machine having a winding composed of coils having a plurality of turns, a power supply for generating a surge voltage, a partial discharge detecting means for detecting a partial discharge of an insulating layer between turns, Insulation between coil turns, comprising: a measuring and judging means for evaluating a partial discharge amount, and arranging the partial discharge detecting means on a connection line between a winding of a rotating electrical machine to be measured and the power supply device. Soundness evaluation device. 2. The device according to claim 1, wherein the partial discharge detecting means has a function of canceling a charging current of a capacitance formed by a coil insulating layer of the winding of the rotating electrical machine caused by a surge voltage generated in the power supply device. An insulation integrity evaluation device between coil turns. 3. The partial discharge detection means according to claim 2, wherein said partial discharge detection means comprises a through-type high-frequency current transformer, and simultaneously applies a surge voltage from said power supply device to an arbitrary selected two-phase winding of said rotating electric machine. An insulation soundness evaluation between coil turns, which is applied in the opposite polarity and penetrates a connection line to each phase winding in the same direction through the penetration type high-frequency current transformer. 4. The power supply device according to claim 3, wherein the power supply device that generates the surge voltage also serves as an inverter drive power supply that controls rotation of the rotating electric machine, and the wiring is kept at a predetermined or arbitrary timing during normal operation. An insulation integrity evaluation device between coil turns, wherein a surge voltage for measurement is generated by driving an inverter. 5. The partial discharge detection means according to claim 2, wherein said partial discharge detection means comprises a through-type high-frequency current transformer, and simultaneously applies a surge voltage from said power supply device to an arbitrary selected two-phase winding of said rotating electric machine. An insulation soundness evaluation device between coil turns, wherein the voltage is applied and connection wires to the respective phase windings are passed through the high-frequency current transformer of the penetration type in mutually opposite directions. 6. The insulation sound between coil turns according to claim 1, wherein the power supply device that generates the surge voltage is a power supply device that changes the magnitude of the surge voltage and the steepness of a rising portion thereof. Sex evaluation device. 7. The partial discharge current pulse according to claim 1, wherein the measurement determination unit receives an output of the partial discharge detection unit, and cancels and detects a charge current of a capacitance formed by the coil insulating layer. Characterized in that the relationship between the detected partial discharge amount and the magnitude of the surge voltage and the steepness of the rising portion thereof is measured. 8. The inter-turn insulating layer according to claim 7, wherein the measuring and judging means determines a relationship between a magnitude of the surge voltage exceeding a threshold value of a fixed partial discharge amount and a steepness of a rising portion thereof. An apparatus for evaluating insulation integrity between coil turns, wherein a partial discharge between a coil and a ground insulating layer is distinguished and determined. 9. A turn-to-turn insulation by applying a surge voltage to a line side terminal of a winding composed of a coil having a plurality of turns to generate a high voltage between turns of the coil close to the line side of the winding. A partial discharge is generated in the layer, and the relationship between the detected partial discharge amount and the magnitude of the surge voltage and the steepness of the rising portion thereof is measured. A method for evaluating insulation integrity between coil turns, characterized by making a distinction from partial discharge.