Experimental Investigation on Corona Charge-Voltage Characteristics in the Coaxial Configuration under Lightning Impulse Voltages

Surge corona losses are of great importance in insulation coordination studies for high voltage transmission systems; corona losses are most often calculated based on charge-voltage curves, which follow a hysteresis loop. The enclosed area of the charge-voltage curves relates to the associated energy dissipation by corona for the full duration of the overvoltage surge. This study presents an experimental investigation on the charge-voltage characteristics of the lightning impulse corona in the coaxial cylindrical electrode arrangement. Corona inception characteristics namely time, voltage and charge were measured and the associated energy losses were estimated. To investigate the dependence of corona characteristics on the amplitude of the applied impulse voltage, the gap was overstressed. As the applied voltage increases, a transition from the glow to streamer mode of corona inception occurs. Where stable streamer corona is established, the corona charge and the associated energy losses are approximately two times lower for negative than positive corona.