Technique for calibrating V probes

V probes designed by Maxwell Laboratories, Inc. (MLI) have been extensively used at the Air Force Weapons Laboratory to measure the voltage of fast capacitor banks. The straightforward calibration method of pulsing a high voltage across the voltage probe typically produces only millivolts of output signal. Based on a suggestion by MLI, a new method to calibrate the probes has been devised. This technique, which uses a capacitive discharge and measures the dV/dt directly, has the advantage of producing an output signal of nearly a volt. A circuit has been designed and constructed to provide an appropriate ringing discharge which can be used to calibrate V probes. The theory of V probes and their calibration is discussed, and the construction and operation of the discharge circuit is presented. Finally, as an example of the calibration technique, details of how to calibrate a V probe are presented. A precision of 4% is readily attainable in the V probe calibration. Such accuracy should make possible routine 5% voltage measurements on pulsed power systems