JP2683544B2 - Insulation diagnosis method for windings of rotating electrical machines - Google Patents

Description

The present invention relates to an insulation deterioration diagnosis method for measuring the degree of insulation deterioration of a winding of a rotary electric machine.

[Conventional technology]

Generally, the reliability of rotating electrical machines, such as generators and electric motors,
A major factor affecting the life is deterioration of the insulation of the winding. When renewing insulation for this life, accurate evaluation of the degree of insulation deterioration is desired.

Therefore, various kinds of methods have been considered as this kind of insulation diagnosis method, and a partial discharge test, a tan δ test, etc. are known as methods for diagnosing electrical insulation deterioration.

Methods of measuring the degree of insulation deterioration from the partial discharge test include partial discharge inception voltage / extinguishing voltage measurement and cumulative occurrence frequency-discharge charge characteristics (parameter: voltage).

Further, as a method of measuring the degree of insulation deterioration from the tan δ test, there is tan δ-voltage characteristic. In this case, as insulation deterioration of the winding progresses, the tan δ value below the partial discharge inception voltage is smaller than that in the case where insulation is complete, and it is often said that the tan δ increase initiation voltage also decreases. Some types of insulation do not appear clearly, and the degree of insulation deterioration is estimated by the tan δ value at a voltage higher than the tan δ increase start voltage. In addition, it was necessary to apply a voltage higher than the tan δ increase start voltage to the winding having a good insulation and the winding having deteriorated.

[Problems to be solved by the invention]

However, in the partial discharge test, when measuring the partial discharge inception voltage and extinction voltage, the relationship between the measured value and insulation deterioration may not appear clearly, and there are variations in the reading method by the measurer, and the cumulative occurrence frequency- When measuring the discharge charge characteristics, since a constant voltage is applied and the measurement is performed, there is a risk of dielectric breakdown during measurement if the degree of insulation deterioration of the test winding is advanced.

Further, in the tan δ test, there was a risk of dielectric breakdown during the measurement as described above.

The present invention is a method devised in view of the above-mentioned points, and an object thereof is that the degree of insulation deterioration can be accurately measured in a short time, and the degree of insulation deterioration of the test winding is advanced. It is an object of the present invention to provide a method of diagnosing insulation of windings of a rotating electric machine, in which a voltage that does not cause dielectric breakdown is applied during measurement.

[Means for solving the problem]

In other words, the means for achieving the object is the discharge diagnostic that occurs when a voltage is applied to the winding in the insulation diagnosis method that measures the progress of insulation deterioration of the winding of the rotating electric machine based on the change in the electrical characteristics. When measuring the charge amount, the cumulative occurrence frequency of a certain partial discharge charge amount or more and the voltage applied to the winding are measured at the same time and recorded in the recording device, and the constant partial discharge is generated as the applied voltage rises. The purpose is to measure the degree of insulation deterioration by the degree of increase in the cumulative frequency of occurrence of charges or more. Further, as described in claim (2), when the partial discharge charge amount reaches a certain set cumulative generation frequency of the cumulative frequency, the applied voltage is cut off and a voltage higher than necessary is applied to the winding. There is also a method of making a diagnosis in which no voltage is applied.

[Action]

The effect is that when the test insulator is complete, there are only small voids, that is, voids, inside the insulator, the starting voltage of partial discharge is relatively high, and the number of occurrences is small at the same applied voltage. However, as the insulator under test repeatedly expands and contracts under the influence of heat, cracks occur in the insulating layer and the voids become larger than at the initial stage, and the number of partial discharges increases even at the same voltage. Come on. Therefore, as shown in FIG. 2, the degree of insulation deterioration can be known by the degree of increase in the cumulative occurrence frequency of a certain partial discharge charge or more with respect to the increase in the applied voltage.

The diagnostic method of the present invention is a method utilizing the phenomenon,
Further, as described in claim (2), while measuring the cumulative occurrence frequency of a certain amount of discharge charge or more, a limit of the cumulative occurrence frequency is set, and when the cumulative occurrence frequency is reached, it is applied to the specimen. In some cases, it may try to cut off the voltage being applied.
This makes it possible to prevent application of an unnecessarily high voltage to the test insulator.

An embodiment of the diagnostic method of the present invention will be described in detail below with reference to the drawings.

〔Example〕

FIG. 1 is a measurement circuit diagram showing an embodiment of an insulation deterioration diagnosing method of the present invention. In FIG. 1, 1 is a test insulator for diagnosis of insulation deterioration, 2 is a partial discharge measuring instrument, and 3 is A power supply device 4 is a recording device for simultaneously recording an applied voltage signal a from the power supply device 3 to the test insulator 1 and a cumulative occurrence frequency signal b from the partial discharge measuring instrument 2 which is equal to or higher than a certain set Coulomb value,
Reference numeral 5 is a coupling capacitor, and 6 is a blocking coil.
Further, the partial discharge measuring instrument 2 generates a shutoff signal c for shutting off the power when the cumulative occurrence frequency is equal to or higher than the set cumulative occurrence frequency so that an excessive voltage is applied to the test insulator 1 so as not to cause dielectric breakdown. The power supply device 3 receives the cutoff signal c and cuts off the voltage applied to the sample. Here, 3a is a voltage regulator, and 3b is a test transformer.

Thus, the graph output from the recording device 4 in the measuring device configured as described above is shown in FIG.

That is, the content shown in claim (1) will be described below. In FIG. 2, the set coulomb value of the partial discharge measuring instrument 2 is set to, for example, 1000 PG, and the cumulative part occurrence frequency is 2000 PPS (the number of occurrences per second). The voltage is measured from 0 to 500V for 1 second and the maximum voltage is up to 5KV.

As can be seen from Fig. 2, the slope (PPS / KV) becomes steep up to 2000PPS as the heating deterioration time becomes longer.

FIG. 3 is data showing the tan δ value and the dielectric breakdown voltage residual rate at the time of measurement when voltages of 5 KV, 3 KV, and 1 KV were applied to the same test insulator 1, respectively.

From the figure, the decrease in the dielectric breakdown voltage residual rate and the increase in the tan δ _5KV value are in good agreement, and it is necessary to apply a high voltage to the test insulator 1 having advanced deterioration. On the other hand, when the measured voltage is low and becomes 1 KV, the tan δ _{1 KV} value has a drawback that the residual rate of dielectric breakdown voltage does not change even after the thermal deterioration time, and the degree of deterioration cannot be estimated.

On the other hand, as shown in FIG. 2, the gradient becomes steeper as the degree of insulation deterioration progresses. Here, the discharge starting voltage of the test insulator 1 is E ₁ (V), Accumulation frequency
When the voltage at the time of reaching 2000PPS is E ₂ (V) and the set cumulative part occurrence frequency is n _pps , the deterioration index I becomes I = n / (E ₂ −E ₁ ). Considering this, the dielectric breakdown voltage residual rate The characteristic showing the relationship with is shown in FIG.

From the figure, the relationship between the deterioration index I and the residual rate of dielectric breakdown voltage can be well understood. The set cumulative portion occurrence frequency n may be appropriately converted depending on the type of the insulator 1 under test.

According to the diagnostic measuring method using such a measuring device, the measurement can be performed in a short time, and the lower the voltage, the lower the degree of deterioration of the specimen. Then, the dielectric breakdown voltage residual rate can be estimated by the deterioration index that does not include individual differences.

Next, the contents described in claim (2) will be described with reference to FIGS. 1 and 2.

From Fig. 2, it can be seen that the insulation under test has advanced insulation deterioration, eg 90
After 0 hours, the number of partial discharges was 2000 PPS or more at a voltage of 2 KV, and an applied voltage higher than that would cause dielectric breakdown of the tested insulator. Therefore, in order to prevent such a situation, as described above, when the discharge charge amount reaches a certain set cumulative occurrence frequency, the voltage is applied from the partial discharge measuring instrument 2 to the power supply device 3 to the test insulator 1. This is a method of generating a cutoff signal c in order to quit.

When the test piece is grounded, the measuring circuit can be determined by the coupling capacitor detection method in the same manner as described above.

〔The invention's effect〕

As described above, according to the present invention, the measurement time is as short as 10 seconds at the longest, and if the insulation deterioration progresses, it ends in about 3 seconds, and the applied voltage becomes lower accordingly. In addition, the residual rate of dielectric breakdown voltage can be easily estimated from the deterioration index.

Therefore, the method for diagnosing insulation deterioration of windings of a rotating electric machine according to the present invention is extremely useful in practice.

[Brief description of the drawings]

FIG. 1 is a measurement circuit diagram showing an embodiment of the insulation deterioration diagnosing method of the present invention, FIG. 2 is a graph characteristic diagram output from the recording apparatus of FIG. 1, and FIG. 3 is a graph showing the measurement method of the present invention. Data characteristic diagram that measured the degree of insulation deterioration by other electrical methods,
FIG. 4 is a characteristic diagram showing the relation between the deterioration index derived from FIG. 2 and the dielectric breakdown voltage residual rate. 1 ... Test insulator, 2 ... Partial discharge measuring device, 3 ... Power supply device, 4 ... Recording device, 5 ... Coupling capacitor, 6 ...
Blocking coil.

Claims (2)

(57) [Claims] 1. An insulation diagnosis method for measuring progress of insulation deterioration of windings of a rotary electric machine based on a change in electrical characteristics,
When measuring the discharge charge amount generated when a voltage is applied to the winding, the cumulative occurrence frequency of a certain partial discharge charge amount or more and the voltage applied to the winding are simultaneously measured and recorded in a recording device. A method for diagnosing insulation of windings of a rotating electric machine, characterized in that the degree of insulation deterioration is measured by the degree of increase in cumulative occurrence frequency of a certain partial discharge charge amount or more with respect to increase in applied voltage. 2. With respect to the cumulative occurrence frequency, when the partial discharge charge amount reaches a certain set cumulative occurrence frequency, the applied voltage is cut off so that an excessive voltage is not applied to the winding. A method of diagnosing insulation of windings of a rotating electric machine according to claim 1.