Lightning impulse neutral point current waveform high frequency oscillation suppressor and test circuit

Abstract

The application discloses a lightning impulse neutral point current waveform high-frequency oscillation suppressor and a test circuit. The high-frequency oscillation suppressor comprises a shielding shell, a high-voltage high-frequency filter assembly is arranged in the shielding shell, the shielding shell is grounded through a grounding wire, and a wiring terminal is arranged on the shielding shell. The test circuit comprises a damage indicating resistor, the high-frequency oscillation suppressor and a waveform recorder which are connected in parallel. The application can effectively suppress the high-frequency oscillation interference signal superimposed in the neutral point current waveform during the lightning impulse test of a transformer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of transformer high voltage test equipment, in particular to a lightning impulse neutral point current waveform high frequency oscillation suppressor and test circuit. BACKGROUND

[0002] The lightning impulse test is a routine test that must be performed for each transformer product as a high voltage insulation test. The purpose of the lightning impulse test is to ensure that the power transformer can withstand the corresponding voltage level lightning impulse overvoltage in the safe operation of the power system.

[0003] Currently, the neutral point injury current method is generally used to obtain the judgment basis for the lightning impulse test of the transformer. The neutral point injury current method is to collect and record the current waveform flowing through the neutral point terminal of the test winding and the injury resistance by means of the injury resistance connected between the neutral point terminal of the test winding and the ground, and to compare the current waveform changes under the reduced voltage and the full voltage, so as to judge whether the transformer test product has a fault.

[0004] In actual testing, since the neutral point injury current method is a fault detection method with high sensitivity, high frequency interference signals may be introduced into the waveform due to the high sensitivity in actual testing, thereby affecting the normal judgment of whether the transformer is faulty. SUMMARY

[0005] The purpose of the present application is to provide a lightning impulse neutral point current waveform high frequency oscillation suppressor and test circuit to solve the problem of introducing high frequency interference signals in the neutral point injury current method of the prior art transformer test.

[0006] In order to achieve the above purpose, the technical solution adopted by the present application is:

[0007] The principle of inverted LC filter is used, wherein the long return lead from the test product to the connection point is an inductor L, and the suppressor is mainly matched with the capacitor. The characteristic is that it includes a stainless steel shielding shell, a high voltage (2000V) high frequency filter component capacitor is arranged in the shielding shell, the shielding shell is grounded through a grounding wire, a high voltage insulated lead-out terminal is arranged on the shielding shell, and the high voltage high frequency filter component capacitor is connected with the external circuit through the lead-out terminal.

[0008] A lightning impulse test circuit includes an injury resistance, a waveform recorder, the injury resistance is connected between the neutral point of the transformer to be tested and the ground, the injury resistance and the ground are connected with the waveform recorder through a wire, and the high frequency oscillation suppressor is also included, and the high frequency oscillation suppressor is connected to the injury resistance.

[0009] The lightning impulse neutral point current waveform high-frequency oscillation suppressor can effectively suppress the high-frequency oscillation interference signals superimposed on the neutral point current waveform when the transformer adopts the neutral point injury current method to perform lightning impulse test.

[0010] The lightning impulse neutral point current waveform high-frequency oscillation suppressor is connected in parallel with the injury resistance in the test circuit, so that the purpose of effectively suppressing the high-frequency oscillation interference signals superimposed on the neutral point current waveform can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is the structure diagram of the high-frequency oscillation suppressor of the embodiment.

[0012] Figure 2 is the principle diagram of the lightning impulse test circuit of the embodiment. DETAILED DESCRIPTION

[0013] The application will be further described below in combination with the drawings and embodiments.

[0014] As shown in the figure, the embodiment discloses a test circuit applying the high-frequency oscillation suppressor of the embodiment one, which comprises an injury resistance R, a digital waveform recorder RE, and the high-frequency oscillation suppressor HY disclosed by the embodiment one. Figure 2

[0015] The high-voltage winding T1 of the transformer to be tested used in the application adopts star connection, and the low-voltage winding T2 adopts triangle connection. The A-phase terminal of the high-voltage winding T1 is loaded with an impulse voltage U, and the C-phase terminal and the D-phase terminal of the high-voltage winding T1 are grounded. The A-phase terminal, the B-phase terminal, and the C-phase terminal of the low-voltage winding T2 are grounded.

[0016] One end of the injury resistance R is connected to the high-voltage neutral point O of the transformer to be tested, and the other end of the injury resistance R is grounded. The high-frequency oscillation suppressor HY is connected in parallel with the injury resistance R. The voltage is divided between the impedance of the tested product and the injury resistance, and the digital waveform recorder is connected to the first end of the injury resistance through a coaxial cable. The resistance value of the matching resistance R' is equal to the resistance value of the coaxial cable Z. Thus, the voltage of the high-voltage neutral point O is transmitted to the digital waveform recorder RE through the injury resistance R, the coaxial cable Z, and the matching resistance R', and the current waveform of the high-voltage neutral point O is collected by the digital waveform recorder RE.

[0017] The embodiments described in the application only describe the preferred embodiments of the application, and do not limit the concept and scope of the application. Without departing from the design idea of the application, various modifications and improvements of the technical solutions of the application made by the engineering technicians in the field shall fall within the protection scope of the application. The technical content of the application claimed for protection has been fully recorded in the claims.​

Claims

1. A high-frequency oscillation suppressor for lightning impulse neutral point current waveform, which utilizes the principle of inverse LC filter, the high-frequency oscillation suppressor is arranged in matching with the capacitor, characterized in that, It comprises high-voltage access terminal (1), terminal (2) for measuring lead-out, terminal (3) for ground connection, metal shell (4) for shielding, inductor (5), high-voltage high-frequency filter assembly capacitor (6); the shell of metal shell (4) for shielding is provided with high-voltage high-frequency filter assembly capacitor (6), the surface of shell of metal shell (4) for shielding is grounded through terminal (3) for ground connection, high-voltage access terminal (1) is arranged on the shell of metal shell (4) for shielding, and high-voltage high-frequency filter assembly capacitor is connected with external loop through terminal (2) for measuring lead-out.

2. A lightning impulse test circuit comprising a damage indicating resistor, a wave recorder, the damage indicating resistor being connected between the neutral point of a transformer to be tested and ground, the damage indicating resistor and ground being connected to the wave recorder by a conductor, characterized in that: It also comprises the high-frequency oscillation suppressor as claimed in claim 1, which is connected in parallel with the indication resistance.

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