Research on Ultra-Wide-Band High Voltage Measuring System Utilizing Electric Field Sensing

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The divider ratio and the response characteristics of the high voltage impulse measuring system, which incorporates the ultra-wide-band high voltage divider designed and manufactured in the previous fiscal year, have been measured experimentally. In general, it is difficult to precisely know the divider ratio by measuring the impedance of individual parts of a high voltage divider at a low frequency. It will be possible to determine the divider ratio without performing the comparison test through the accurate three-dimensional electrostatic field analysis and the measurement of the impedance of the low voltage arm. This time, the divider ratio was determined by the comparison measurement with a low impedance divider.The measured step response of the system with the damping resistor of 200 Ohms achieved 5.5ns of the response time, and 75ns of the settling time. These numbers are comparable to those of the best high voltage dividers ever reported, and are not foreseen for dividers having … More high impedance. Thus it has been demonstrated that the developed high voltage measuring system has an ultra-wide-band characteristic. These numbers well clear the requirements for the fastest reference measuring system, demanded by the relevant IEC Standard totally revised in November 1994.The drawback of this type of a high voltage measuring system is that the divider ratio is susceptible to the distortion of surrounding electrostatic field due to the presence of other objects in the vicinity. This effect has been evaluated through a three-dimensional electrostatic field analysis and experiments. The accuracy of plus minus 0.5% is demanded for a reference measuring system according to the revised IEC Standard. As a result of the present study, the height of the lead wire connecting the high voltage divider and the impulse generator or the object under test is known to have little influence on the accuracy of the measurement. The manufactured 1MV-class high voltage measuring system kept its accuracy when the divider was more than 7m away from the impulse generator or the object under test, and was more than 4m apart from grounded objects or the walls of the laboratory. As these limitations can easily be overcome at a large high voltage laboratory, so the usefulness of the high voltage measuring system designed and manufactured in the present study has been confirmed. Less