High-Impulse Current and Voltage Measurement

This paper is a survey of methods of high-impulse current and voltage measurement. Typically, such measurement techniques must now include capabilities for measuring high-energy impulses having peak powers as high as many megawatts, currents as high as many mega-amperes, or voltages as high as several megavolts, with rise times as short as a fraction of a microsecond (even as short as the subnanosecond range for moderately high-energy impulses). These capabilities had to be attained in recent years to meet the needs of various areas of scientific research employing such high-energy impulses. This represents a significant extension in the state of the art of such measurement techniques beyond their more traditional role in development and testing of high-voltage bulk power system equipment. The three most commonly used methods of high-impulse current measurement are the magnetic probe, current transformer, and "pure" resistive shunt methods. These methods are treated in considerable detail. High-voltage capacitive dividers, resistive dividers, and reflection-type attenuators are covered as the principal methods of high-impulse voltage measurement, with some added discussion of the means of insulating such devices. A brief description is given of schemes involving use of laser light sources to measure high-impulse currents and voltages by means of magnetooptic and electrooptic effects. Diagnosis of the complete properties of high-power pulses is also discussed. The emphasis throughout the paper is on a review directed toward practical measurement considerations and techniques.