Corona Measurement on High-Voltage Apparatus Using the Bushing Capacitance Tap

A method of corona measurement on high-voltage apparatus which uses the capacitance tap of the entrance bushing as a coupling element is described. The advantage of this method is that it produces a 1-to-1 calibration ratio for most cases by the use of compensating elements at the measuring frequency. Since the high-voltage coupling capacitor is eliminated, the test circuitry is simplified, and the time and effort normally required for this type of measurement is reduced. Theoretical and factual data are given to support the use of this method as an alternative to NEMA Standard Publication 107, 1940 and 1964.