Takayuki Wakimoto

High-Accuracy Comparison of Lightning and Switching Impulse Calibrators

This paper summarizes the results of a comparison on two calculable impulse voltage calibrators and one commercial calibrator between Helsinki University of Technology, Finland (MIKES-TKK), Nippon Institute of Technology, Japan (NIT), and Physikalisch-Technische Bundesanstalt, Germany (PTB). The peak voltage levels of the comparison ranged from 10 to 300 V. Both lightning and switching impulse voltage calibrators were studied using both positive and negative polarity impulses. The comparison was performed by applying impulses from the calibrators to a 12-b digitizer and then comparing the reported digitizer errors. For the switching impulse peak value, the agreement between the two calculable calibrators was better than 0.02% for all the measured voltages and better than 0.4% for the time parameters. For the lightning impulse peak value, the disagreement between the same two calibrators was smaller than 0.05% for all voltages examined and smaller than 1% for the time parameters

Development of Japan's National Standard Class 500 kV lightning impulse voltage divider

This paper describes the details of the Japans 500 kV National Standard Class Divider whose unit response parameters are measured to be better than the already developed 700 kV Reference Divider, which fulfils IEC-60060 requirements. The 500 kV divider has a specially tuned compensating circuit in the low voltage arm, making its unit step response quite close to an ideal. Also in the paper, the tuning technique, which makes the experimental response time almost zero, is discussed.