Measurement method of high-frequency transformer factory insulation test voltage based on material insulation life
A high-frequency transformer, insulation test technology, applied in the direction of testing dielectric strength, etc., can solve the problems of reducing the electrical strength of insulating materials, reducing the insulation performance, and the probability of thermal instability of the medium, achieving reliable test results, eliminating influence, The effect of good engineering application and promotion value
Inactive Publication Date: 2020-09-15
INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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"However, for high-frequency transformers, the insulation performance of insulating materials will decrease rapidly when the frequency increases. According to the standard IEC 60664-1, increasing the test frequency will lead to a significant increase in the probability of dielectric heating and thermal instability, reducing insulation. The electric strength of the material, the change of the frequency at this time will have a great impact on the results of the induction withstand voltage test, so the original power frequency transformer induction withstand voltage test method is no longer applicable to high frequency transformers
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[0044] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0045] Step 1: Select the insulation material according to the type, model and actual insulation thickness of the insulation material used in the high-frequency transformer winding, and use the power frequency and high-frequency insulation test platforms to test the performance of each insulation material under the 0.5kV / s constant speed boost method. Breakdown voltage, get the breakdown voltage value U at power frequency s ’ and a series of breakdown voltage values U under j frequency in the range of 1~20kHz si , where i indicates that the frequency points in the range of 1~20kHz are sorted from low to high, that is, [i=1,2,3...j];
[0046] Step 2: Select 95% U respectively s , 90%U s , 85%U s , 80%U s , 75%U s , 70%U s As the test pressure value, the breakdown time data set of the selected insulating material at different frequencies...
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The invention relates to a material insulation life-based high-frequency transformer pre-delivery insulation test voltage measuring method. According to the method, a test platform is adopted to carryout a withstand voltage test on a winding insulation material; 1 min breakdown voltages are calculated based on a V-t characteristic; a ratio of a 1 min breakdown voltage corresponding to the material under a condition of a fastest electric aging rate and a breakdown voltage corresponding to the expected life of a transformer is extracted; the recommended values U1 and U1' of external applied withstand voltage test voltages under high-frequency and power-frequency test conditions are obtained according to a power frequency-high-frequency breakdown voltage conversion factor p; a breakdown voltage-frequency (V-f) characteristic is obtained based on Weibull distribution; the ratio k2 of a characteristic breakdown voltage under a rated frequency to a characteristic breakdown voltage under a b-times frequency is calculated; and induced overvoltage withstand test voltage recommended values U2 and U2' of the high-frequency transformer under a high-frequency and power-frequency test system are determined separately. The test voltage recommended values obtained by the method are applicable to the pre-delivery test of the high-frequency transformer under the power-frequency and high-frequency test conditions, and therefore, the method has a high engineering application value.
Description
technical field [0001] The invention relates to a method for measuring the voltage of a high-frequency transformer ex-factory insulation test. Background technique [0002] High-frequency transformers are essential core devices in new power equipment such as power electronic transformers and high-voltage DC converters. The insulation performance of transformers determines the operational reliability of power electronic equipment. The port voltage of a high-frequency transformer is usually a non-sinusoidal excitation signal with a short rise time, a large amplitude, and a high frequency. The electro-thermal coupling effect causes the aging of the solid insulating material to aggravate. In long-term operation, the breakdown of the insulating material of the high-frequency transformer The probability is greatly improved compared with power frequency conditions. Therefore, the insulation life of solid insulating materials at high frequencies has become the main determinant of t...
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IPC IPC(8): G01R31/12
Inventor 赵义焜张国强李康
Owner INST OF ELECTRICAL ENG CHINESE ACAD OF SCI