不同介质中MOV小电流特性的对比研究

氧化锌电阻片(MOV)常用于过电压保护,其小电流特性决定了它的工频稳定性。随着电力技术的发展,MOV被应用于变压器绕组内部和超导电力系统中,MOV的工作介质为变压器油和液氮。将MOV在空气和变压器油、空气和液氮(77K)中分别进行对比试验,通过小波变换对原始数据进行去噪,利用各次谐波法提取阻性电流进行对比分析,结果显示:MOV在变压器油中的阻性电流峰值大于空气中的值,MOV在液氮中的晶界电容、阻性电流峰值均小于空气中的值。表明MOV的小电流特性在空气中优于变压器油中,在液氮温区优于常温下。

Study on Electric Characteristics in Low Current Region of MOV in Different Dielectrics

Metal oxide varistor(MOV) is commonly used in the over-voltage protection.The working stability of MOV depends on the electric characteristics in low current region.With the development of electric technology,MOV will be used in inner protection of transformer windings,and superconducting power systems.In this paper,MOV is tested in the dielectrics of air,transformer oil,and liquid nitrogen(77 K),respectively.The origin data is de-noised by taking the wavelet transform.The resistive current is analyzed with the harmonic method.The results indict that the peak value of the resistive current of MOV in the air is greater than that in the liquid nitrogen,but less than that in the transformer oil,and the capacitance of MOV in the liquid nitrogen is less than that in the air.Conclusion is made that the electric characteristics in low current region of MOV in the air is better than that in the transform oil,but worse than that in the liquid nitrogen.