Characterization and Experiment of attenuators used in lightning impulse measurement
Wenting Li, Zhaozhi Long,Jiawei Fan, Kangmin Hu , Shaobo Liu,Feng Zhou
Measurement Research Institute, China Electric Power Research Institute, Wuhan，China
*363656472@qq.com
Purpose
In the past, much research work has been carried out on the performance of lightning impulse divider and lightning impulse current shunt but less work has been done for the attenuator. It is found that the measurement error between measurement systems with different attenuators was large, which affects the accurate evaluation of the tested voltage value and the current value. It is necessary to analyze and test the attenuators with different type.
Experimental
The transfer functions of resistive attenuators and low-damped capacitive attenuators were analyzed and the scale factor, linearity and time parameter error have been tested by standard lightning impulse voltage calibrator under 1000V with 0.84-60 μs,1.2/50 μs and1.56/60 μs. Based on the step response waveforms of the attenuator ,the convolution integral calculation were also done to evaluate time measurement error of the attenuators.
Results
The attenuator of low-damped capacitive type has better frequency response characteristics. Under three typical lightning impulse voltages, the scale factor consistency was better and the time error is smaller than the resistive type attenuator. Under different tested voltage, the variation of scale factor is less than 0.2%, and the variation of time parameter error is less than 0.5% for the low-damped capacitive attenuator. The variation of scale factor is about 2.0%, and the variation of time parameter error is about 2.0% for the resistive attenuator. Compared with the experimental results, the convolution integral results are very close to the experimental values. The test results will be helpful for the users of impulse voltage measurement system to choose the appropriate type attenuator according to the actual needs.
 

attenuator,lightning impulse,step response,convolution