Performance of a circuit configuration with a common bypass circuit for multiple high-pressure mercury discharge lamps

This paper deals with simulations and experiments carried out on a circuit suitable for use on a multiple number of lag-type high-pressure mercury lamps. One common bypass circuit is provided and a resistance is connected to the power source side of each ballast winding. The properties of the proposed circuit include a nearly sinusoidal input current at unity power factor when one or more lamps are in operation. The self-inductance of each ballast winding is made slightly larger than the rated inductance. The tap position of the bypass circuit is placed closer to the power source side of each ballast winding in order to reduce the input current distortion. The value of resistance in series with the power source side of each ballast winding is designed to provide simultaneous ignition of all lamps. The following findings are obtained with four-lamp circuits with a rated lamp power of 200 W: (1) under steady state, the input current distortion factor is as low as 2%, and the power factor is nearly 100%; and (2) the total loss contributed by the ballast windings, L/sub b/ of the bypass circuit and resistance connected to each ballast winding on the power source side, is as low as 11.4% of the total power.