An electronic electrometer as a versatile corona detector

A new technique is described for the detection and estimation of magnitudes of corona discharges in electric devices during high-voltage testing. This technique employs the electronic electrometer as all instrument to measure the residual charge left in high-voltage structures by both impulse and low-frequency corona or breakdown discharges. For impulse testing, the method can be used with any shape or duration of voltage wave, and for coil sticks it has permitted the prediction of permanent damage and breakdown in many cases. The method is applicable in the testing of high-voltage structures involving at least some solid insulation.