On the development of an impulse current generator

Lightning is known to be the single largest cause of outages on power systems. Protection against lightning invariably consists in employing surge arresters. An important performance criterion for an arrester is the residual voltage. The measurement of residual voltage employs an impulse current generator. This work deals with design and development of 10 kA, 50 kV, 5 kJ impulse current generator. The generator consists of a capacitor bank (3.6 /spl mu/F, 50 kV) capable of being charged from a charging set rated 50 kV DC based on a half-wave rectifier, noninductively wound waveshaping resistors and an air cored coil (waveshaping inductor). A triggered hemispherical gap is used as a switch to initiate the current impulse. Triggering is done by distorting the field of the sphere gap using a third electrode to which an electrical pulse is given from a trigger circuit based on ignition coil. Impulse current is monitored using the noninductive resistive shunt of the radial type built using a double sided copper clad PCB. Residual voltage measurements are performed using a high voltage resistive potential divider.