Circuit analysis of metal-halide lamp with inductive-capacitive ballast

An idealised characteristic for the dynamic behaviour of the metal-halide lamp at 50 Hz is used in the circuit analysis for the series inductive-capacitive ballast. Distortion of the current waveform is shown to increase when the capacitor-impedance/inductor-impedance ratio is increased, or when the supply-voltage/lamp-voltage ratio is decreased. The voltage developed across the inductor at the end of each halfcycle determines the condition for commutation. This voltageis evaluated as a function of supply and lamp voltage and the commutation of the series inductive-capacitive ballast is compared with an inductive ballast.