Experimental Research on Aging Characteristics of MOV Under 8/20 μs Impulse Currents with Different Source Impedances
With a view to studying the impacts of 8/20μs impulse currents with different source impedances on the characteristics of MOV (metal oxide varistors) typed SPD (surge protective device),the SPD was tested with two types of measured pulse generators with different source impedances-Haefely psurge 30.2 and ICGS according to the IEC 61643-1:2005.As indicated in the experimental analysis,firstly,the MOV static,dynamic and dielectric characteristics were closely related to the source impedance.The leakage current,the U1 mA,and the dielectric characteristics are positively related to the source impedance and output residual voltage.Secondly,during the MOV motion under the impacts of impulse current,the residual voltage was less related to the impulse current and the error of the impulse current rise time,but it was largely affected by the steepness of the step voltage waves.In the aging process under large-scale impacts,the current capacity of Im1,Im2/Im1,T2/T1 was small,which could not reflect the aging degree of MOV.Thirdly,the tanθ would represent a dispersive region,which would disappear with the more testing.And the variation tread ofIleakage could be forecast by the Gauss equation,the b1/(c1) 2,b2/(c2) 2 may represent the regularity between Ileakage and source impedance of impulse generators.
source impedanceimpulse testingstep voltage wavestatic parameterdielectric characteristicsGauss fitting
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