The Output Characteristic Analysis Of New Short Circuit Test Device Based On The Electronic Switch

Short circuit test is one of the most important tests for the low voltage switching equipment. This paper researched a new type of short-circuit test equipment based on electronic switch, the choice of phase switch of this short-circuit test equipment has the characteristics of high accuracy choose phase switching angle, high accuracy on time control precision,small switching dispersion。In this paper, the principle and technical parameters of each part of the short circuit test equipment are studied, compared the influence of output caused by electronic switch and mechanical switch, and the phase selection switch module based on the IGBT device is the key researches,analyzed the influence of the short circuit current amplitude caused by the switching angle,found the reason of the current imbalance situation caused by parallel IGBT module and puts forward the solutions, we also made the simulation and experimental validation.The power factor of the test circuit affects the crest factor of short circuit output current waveform,GB 10963.1-2005 clearly define the different test current of the corresponding power factor size, after analyzed the three methods(ratio method, dc attenuation method and phase relations method) proposed in the IEEE Std C37.26-1972 and the five methods(dc component method, impact coefficient method, phase Angle difference method, measuring the whole impedance method and direct reading method) proposed in GB 998-1982,this paper proposed a new power factor measurement method suitable for the short duration short current,This method is suitable for the calculation of short shortcircuit test circuit’s power factor, not limited by the power factor size, has the advantages of good stability, and we analyzed the error of this method,did the Simulation calculation and the actual calculation.In order to make the actual power factor of test circuit to meet the requirements of the standard, GB14048.1-2006 and other standards provision that it should do expect test before the test,make the test circuit output current and power factor to achieve the requirements of the standard, but we generally adjust the impedance of the circuit by experience in practice, it often need many tests to meet the requirements,so this paper introduced impedance calculation method of the each part of the test loop,gave a technical advice for how to fast setting the parameters of the test loop,also introduced the calculation of the maximum test current and the voltage fluctuation.