JPS6153577A - Partial discharge measuring apparatus - Google Patents

Abstract

PURPOSE:To enable accurate and efficient testing of partial discharge with a reduction in the measuring time, by providing charge segmentation circuits and counting circuits equivalent to the number of steps of charge segment values to perform a specified computation for discrete values. CONSTITUTION:Pulses only in the size exceeding the charge segment values are extracted from discharge pulses which are detected with an input circuit 5 and passed through an amplification circuit 6 with discharge segmentation circuits 11 which are arranged equivalent to the number of steps of charge segment values and have thresholds corresponding to the charge segment values. Then, the discharge pulses exceeding the respective charge segment values are counted with counting circuit 12 provided corresponding to the respective circuits 11. The individual descrete values thus obtained are memorized temporarily into a memory computation circuit 13 and the difference of the descrete values between the adjacent discharge segment values is computed to determine cumulative frequencies of pulse generations for each segment value, which is shown on a display 14 in terms of the segment value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a partial discharge measuring device used for partial discharge testing of high voltage electric equipment insulation or insulating materials used.

[Prior art and its problems]

If defects such as bubbles or cracks are present in the insulation made of solid insulators of positive voltage electrical equipment, when voltage is applied to the electrical equipment, the gas in the defects causes spark discharge, resulting in so-called partial discharge. Therefore, the discharge pulse flowing through the test circuit due to this partial discharge is detected, and the amount of discharge charge, discharge starting voltage, discharge extinction voltage, and number of discharge pulses per unit time (
By measuring pulse generation frequency), it is possible to roughly estimate the size and shape of defects in insulation from these quantities. It is also possible to estimate deterioration over time. For these reasons, partial discharge testing is widely known as a nondestructive analysis method or insulation diagnostic method for high-voltage 1B electrical equipment insulation, and various partial discharge measurement devices are commercially available for use in this partial discharge test. (For example, CD-5/PDC-5 type measuring instrument manufactured by Nippon Kei 611j Instrument Manufacturing Co., Ltd.)
.

FIG. 5 is a conceptual diagram showing the configuration of a conventional partial discharge measuring device connected to a partial discharge test circuit. In the figure, reference numeral 1 denotes a test object, which is connected to an AC high voltage power supply 2 via a blocker 4, and is connected to the test object 1, a coupling capacitor 3, and an input circuit 5 of a partial discharge measuring device @10. By forming a closed circuit of discharge pulses, the discharge pulse current flowing through the input circuit 5 can be detected. In the case of the figure,
The input circuit 5 has a specific center frequency, for example 150 to 400.
It consists of a tuning circuit having a tuning characteristic at kHz, and a specific frequency component of the original discharge pulse waveform is detected and converted into a pulse waveform that is easy to process. The output pulse of the input circuit is, for example, logarithmically amplified by an amplifier 6 and is then amplified by a variable attenuator 7.
is input to a counter 8 having a predetermined threshold value. Calibration of the amount of discharged charge in this measuring device is performed on the test object 1.
This is done by injecting a known discharge load (hereinafter abbreviated as Q) between both terminals of After that, the variable attenuator 7 is set to a predetermined Q division value, for example, 100PC (IPC is lXl0 coulombs).
, 300PC, 100OPC, and 3000PC, the number of discharge pulses corresponding to one division value can be determined. However, in order to measure a series of partial discharge characteristics such as Q division values and pulse generation frequency (hereinafter abbreviated as N/t) for one test object, it is necessary to change the applied voltage to the test object in steps. At the same time, the variable attenuator 7 is adjusted in the above-mentioned step, the count number of the counter 8 is finally recorded, and the difference between adjacent count numbers N is calculated to calculate the value of N/ corresponding to the division value of Q. There is a need. Therefore, it has the disadvantage that it takes a lot of time to measure and organize the data, and applying high voltage to the test object for a long time changes the appearance of discharge from defects in the insulation, making it difficult to obtain measurement data with good reproducibility. It has the disadvantage of being difficult to detect, and there is a need for improvement.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation.

It is an object of the present invention to provide a partial discharge measuring device that can shorten measurement time and is therefore suitable for performing accurate and efficient partial discharge tests without being affected by changes in the aspect of discharge.

[Key points of the invention]

In the present invention, the discharge pulse detected by the input circuit and amplified by the amplifier circuit is transferred to the output side of the amplifier circuit (this is a charge amount provided by the number of steps of the charge amount division value and having a threshold value corresponding to the charge amount division value). Only pulses with a magnitude exceeding the division value are output from the quantity division circuit 1, and each charge division circuit t
The number of discharge pulses exceeding the charge amount classification value is counted by a correspondingly provided counting circuit, and the counted value is temporarily stored in a storage arithmetic circuit commonly provided on the output side of the counting circuit. Calculate the difference in the count values between adjacent charge amount division values to find the cumulative pulse generation frequency for each division value,
By configuring this value to be displayed on a display for each category value, the above-mentioned objective is achieved.

[Embodiments of the invention]

The present invention will be explained below based on one embodiment.

FIG. 1 is a block diagram of a measuring device showing an embodiment of the present invention. In the figure, the input circuit 5 and the amplifier circuit 6 are the same as those already described in the prior art. 11
．． IIA, IIB,...

11N is a charge amount classification circuit provided in parallel on the output side of the amplifier circuit 6, and has a threshold value corresponding to the charge amount classification value of the output discharge pulse of the amplifier circuit 6, for example, 100PC, 100
The voltage values corresponding to OPC and 100OOPC are respectively set, and the plurality of charge amount classification circuits 11, 11A, 11B, etc. that receive the output discharge pulses of the amplifier circuit 6 only receive discharge pulses exceeding their respective thresholds. Output. 12
, 12A.

12B, . . . , 12N, etc. are counting circuits provided on the output side corresponding to each of the charge amount dividing circuits. Count the numbers. 13 is a memory/arithmetic circuit provided in common on the output side of each counting circuit.

In addition to temporarily storing the count values of each counting circuit,
Adjacent charge amount division values, for example, 100pc and 1
00OPC, 100OPC and 100OOPC, 1000
The difference between the count values corresponding to 0 PC or more, that is, (N100-
Nl 000) , (Nl 000-NIO000
) , (N100OO or more) is calculated. By rubbing like this.

Charge classification value e.g. (100~1000PC), (10
00 to 100OOPC) and ()100OOPC), the number of pulses generated per second, that is, the division value of the discharge pulse occurrence frequency (Nll) can be obtained.

The display 14 is for displaying or recording the calculation results by the storage calculation circuit. By repeating the above measurement every time the voltage value applied to the object is changed, the display displays characteristic data or a characteristic diagram of discharge charge tQ versus discharge pulse generation frequency N/ with the applied voltage as a parameter. be able to.

FIG. 2 is a circuit diagram showing an example of the charge amount classification circuit in the first embodiment described above, and shows an example in which a peak value discrimination circuit consisting of a differential amplifier is used.

In the figure, 15 is a differential amplifier, and numeral 15 is an input resistance, R.

is the output resistance, and by keeping R1 and RL at predetermined values and setting the threshold value V to a value corresponding to the charge classification value, the input voltage v1 exceeding the threshold value is input. When this happens, a high-level output signal v,) is output to the output side. Note that J), ,D in the figure are diodes for protection against excessive input, and D, ,D.

is a diode for regulating the output level of the output signal v6.

Figures 3 and 4 are characteristic diagrams showing an example of the partial discharge characteristics of the test object obtained using the measuring device of the above-mentioned embodiment, and Figure 3 is a graph of the output count value of the counting circuit. thing,
Figure 4 is a graph of the display contents.
The figure is a characteristic diagram that can be displayed directly on a display. In FIG. 3, a curve 111 is generated in the insulation of the test object when an applied voltage V is applied to the test object 11, is detected by the input circuit 5, is amplified by the amplifier circuit 6, and is detected by the input circuit 5. The charge amount classification circuit 11 compares the respective threshold values, and when the peak value exceeds the threshold, the frequency of occurrence (Nl) of the discharge pulse signal input to the counting circuit (12) and the discharge pulse signal are determined.
A characteristic curve 112 showing the relationship with the load i'Q is a characteristic curve obtained in the same manner as described above when the applied voltage is increased to vz. In this measuring device, a plurality of charge amount classification circuits 11.11A and I are set so that the threshold value increases stepwise in response to a stepwise increase in the charge amount classification value.
As the discharge pulse signal passes through IB etc., the discharge pulse signal whose peak value is lower than the threshold value is truncated, but
Since all pulse signals exceeding the threshold are counted, the cumulative value of the discharge pulse generation frequency N/l is measured in the counting circuits 12, 12A, 12B, etc., and when the discharge charge amount Q exceeds a certain value, Nll Cumulative distribution curves 111, 112 in which Nll becomes zero as Q begins to decrease and Q increases roughly.
etc. will be obtained.

In the conventional device shown in FIG. 5, in order to obtain the curve 111, the applied voltage is held at V, +, and the attenuation amount of the variable attenuator 7 is sequentially increased in accordance with the increase in the division value. Because the measurement procedure of reading the display of 8 was required,
It takes several minutes just to find one curve, and if there are many voltage steps, one measurement can take up to 10 minutes.
During this time, problems such as changes in the aspect of the discharge occurred, but in the device of the present invention, measurements corresponding to each of the curves 111 and 112 are performed simultaneously and in a short period of about 1 second. This has the advantage that the test time is shortened and the measurement can be completed before the aspect of discharge changes.

FIG. 4 is a characteristic diagram showing display data outputted to the display 14, in which the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit, and the output count value signal of the counting circuit 12 is temporarily stored in the storage section of the storage calculation circuit. By finding the difference between the count signals, the cumulative distribution curve in Figure 3 becomes the frequency distribution curve 141.142 l in Figure 4.
By converting this, it is possible to immediately know in what frequency distribution N/l the discharge pulse of discharge charge i-Q is generated with respect to the applied voltage 'i't, Vt, etc. Therefore, there is an advantage that the characteristic curve shown in FIG. 4, which could not be directly obtained with the conventional device, can be automatically displayed.

〔Effect of the invention〕

As described above, the present invention provides a plurality of charge amount classification circuits and a counting circuit having different threshold values after the input circuit and the amplifier circuit, so that the cumulative frequency of discharge pulses versus discharge charge amount characteristic data can be measured simultaneously. 1.A memory/arithmetic circuit is provided on the output side of the counting circuit to enable simultaneous measurement of discharge pulse frequency vs. discharge charge characteristic data. The time required for measurement can be significantly shortened, and the problem of changing the partial discharge pattern of the test object due to the long time required for conventional measurements is eliminated, allowing efficient partial discharge testing with high accuracy. It is possible to provide a partial discharge measuring device that can perform the following steps.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a measuring device showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of the charge amount division circuit in the first embodiment described above, and FIG. FIG. 4 is a partial discharge characteristic diagram showing the content of output data of the counting circuit in the above-mentioned embodiment; FIG. FIG. 5 is a configuration diagram of a conventional measuring device to which one partial discharge test circuit is connected. 1... Object to be inspected, 2... High voltage power supply, 5... Input circuit. 6... Amplification circuit, 7... Variable attenuator, 11. IIA
. 11B, IIN...Charge amount division circuit, 8, 12゜12
A', 12B, 12N...Counting circuit, 13...Storage calculation circuit, 14...Display device, Q...Discharged charge amount, N
/t...Pulse generation frequency. Figure 1 Figure 2 Discharge charge amount Q (logarithmic value) → Figure 3 Sheet 1! Power index quantity Q (logarithmic value) → Calculation 4 Figure Q Figure 5

Claims (1)

[Claims] 1) A measuring device that simultaneously measures and displays the frequency of pulse occurrence for each predetermined discharge charge classification value by detecting partial discharge pulses generated in an insulated part of a test object to which a high voltage is applied, An input circuit that detects and shapes the waveform, an amplifier circuit that receives the output pulses of the input circuit, and a plurality of charge division circuits each having a different threshold value, which are installed in parallel on the output side of this amplifier circuit. a counting circuit provided respectively corresponding to the charge amount division circuit;
A memory calculation circuit is provided in common on the output side of this counting circuit and temporarily stores the output signal of the counting circuit to calculate the discharge pulse generation frequency for each division value, and a storage calculation circuit that temporarily stores the output signal of the counting circuit and calculates the discharge pulse generation frequency for each division value. 1. A partial discharge measuring device characterized by comprising: a display for displaying.