SU1404986A1 - Method of inspecting winding insulation quality - Google Patents

Abstract

The invention relates to electrical measuring equipment and can be used in devices for testing the insulation of electrical products. The aim of the invention is to increase the sensitivity in monitoring the coil insulation, which is achieved by selecting the frequency of the test pulse carrier close to the first resonant frequency of the winding. For this purpose, a high-voltage rectangular radio pulse is applied to the input terminals of the two phases of the test winding in the opposite phase. A device implementing the method comprises a generator 1 of high-voltage radio pulses, a control object 2, a matching cascade 3, a generator of sinusoidal oscillations 4, a circuit 5 for indicating a monitored signal. The increase in sensitivity when monitoring coil insulation is provided by using a high-voltage radio pulse as a control signal. With a slight deviation of the carrier frequency from its own resonant frequency of the winding in the latter, the inter-turn voltages reach a maximum and are evenly distributed along the length of the winding. 1 il. (/) С о о licb QO 00 a

Description

This invention relates to an electrical measuring technique for testing the insulation of electrical products,

The purpose of the invention is to increase the sensitivity in monitoring the turn-through operation due to the choice of the carrier frequency of a test pulse close to the first resonant winding frequency.

The drawing shows a functional diagram of the device that implements the proposed method, I

The circuit contains a generator of 1 high-voltage radio pulses, a control object 2, a matching stage 3, a generator of 4 sinusoidal oscillations, a circuit 5 for indicating a monitored signal.

The method is carried out as follows.

A high-voltage square-shaped radio pulse is applied to the input terminals of the two phases of the test winding in antiphase. The output monitored signal, which is a sinusoidal oscillation of a fixed frequency, is removed between the output of the third phase and the body of the machine. The frequency of the radio pulse carrier f d is set close to the first resonance frequency of the voltage in the phases of the test winding, by varying the duration of the radio pulse, the minimum signal level of the controlled frequency is obtained. The required condition is satisfied when the frequency of the monitored signal coincides with the frequency of one of the spectral density minima of the radio pulse. After that, the input from the second generator of the sinusoidal oscillations, which frequency is equal to the carrier difference, is additionally supplied to the input terminals of the same two winding phases. radio pulse and fixed frequency controlled signal f

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The magnitude of the monitored signal after switching on the second generator into the circuit estimates the intensity of the discharges in the damaged areas of the insulation of the tested phases. A useful signal is generated by multiplying the radio pulse spectra and the signal of the second generator at the ionization sites of the damaged insulation, as on nonlinear circuit elements. Level

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the signal of a controlled frequency is determined by the intensity of the ionization processes in the places of insulation damage and the signal level of the second generator. The correlation between the levels of these signals increases the efficiency of the proposed control method, since it allows detecting the useful signal against the background of interference.

Matching cascade 3 can be made in the form of a pulse transformer. The frequency of the monitored signal f, g differs from the frequency of the generator signal f and the frequencies of the harmonic components of the spectrum of the test pulse of the generator 1. If there are no ionization places in the winding insulation, the control object can be considered a linear system that does not change the spectral characteristics of the signals passing through and, therefore, the signal level at the output of the display circuit 5 is zero

5 those damage to the insulation at a sufficiently high level of test voltage, partial discharges occur, leading to a change in the parameters of the equivalent replacement circuit

0 winding 2 (control object) with the frequency of the carrier pulse. In this part of the circuit, the multiplication of the spectra of signals passing through the winding occurs with the formation of combination frequencies, one of which is isolated and fixed.

An increase in sensitivity in monitoring coil insulation is provided by using a high-voltage radio pulse as a test signal. With an insignificant (2-3%) deviation of the frequency by the non-resonance from its own resonant frequency of the winding in the last, the inter-turn voltages reach a maximum and are evenly distributed along the length of the entire winding.

Claims (1)

Invention Formula The method of controlling the quality of winding insulation, which consists in the fact that the control object is affected by two signals of different frequency and shape, differently with the C aim of increasing the sensitivity in controlling the coil insulation, select the duration of the test signal having the form of a high-voltage signal. a radio pulse machine with a carrier 31404986 frequency close to resonance, whose frequency is equal to the difference the frequency of the test winding, up to the half-carrier frequency and the frequency of control of the minimum signal level, and by the level of the signal controlled frequency, and then controlled frequency is judged on the winding of a sinusoidal signal isolation of the test winding.