Corona Discharge, Flashover (ARC) Detection and Breakdown
All hipot and dielectric test equipment have the ability to detect a breakdown, and some have the ability to detect Flashover (ARC), but only a few like ours have the added ability to detect CORONA DISCHARGE. Although safety agencies have not included any requirement to measure the corona discharge, by accurately measuring the leakage current dynamically in very small levels, it is possible to determine if the unit is in one of the following conditions:
Corona Discharge: an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient (the strength of the electric field) exceeds a certain value, but conditions are insufficient to cause complete electrical breakdown or arcing. Corona discharge may be an early symptom of an impending breakdown.
Flashover: an electrical breakdown of a gas that produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. Vasily V. Petrov, a Russian scientist who discovered it in 1802, first described the phenomenon.
Breakdown: a rapid reduction in the resistance of an electrical insulator that can lead to a spark jumping around or through the insulator. This may be a momentary event (as in an electrostatic discharge), or may lead to a continuous arc discharge if protective devices fail to interrupt the current in a high power circuit.
The graph below shows the association of these three conditions: