Influence of Stray Capacitance on Attenuation Characteristics of Second-order Filter in Cable Resonance Test
The partial discharge needs to be measured during the cable resonance test. To reduce the interference of the partial discharge of the resonant reactor,a second-order filter is required for strict occasions.In this test,80%of the ra-ted voltage is applied to the no-load test equipment,and the partial discharge after filtering is 3 pC,which cannot meet the requirement of less than 1 pC.Through simulation calculations,it is found that the stray capacitance between the filter tail and the voltage divider has great impact on the filtering effect,as smaller stray capacitances correspond to better filter effect. Moreover,with the increase of frequency(20～300 kHz),the attenuation first increases to the maximum,then after a steady minimizing the attenuation rises gradually and tends to be stable.For the results above,the layout of the filter and voltage divider is changed to reduce the stray capacitance between them.It can be found that when the filter and voltage divider are arranged at right angles on the test site,the stray capacitance between them is 50.9 pF,and the partial discharge of the resonant reactor is 3 pC.However,when the filter and voltage divider are arranged in a straight line,the stray capacitance is 36.5 pF,and the partial discharge of the reactor is reduced to 0.8 pC which is less than 1 pC.This re-sult is consistent with the simulation analysis conclusions.
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万方数据
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