METHOD AND CIRCUIT ARRANGEMENT FOR OPERATING A SODIUM HIGH-PRESSURE LAMP

摘要

Sodium high-pressure lamps can be operated using a circuit, which rectifies the a.c. supply voltage and which, while eliminating smoothing, feeds the supply voltage directly to a power inverter for generating a frequency great er than 1 kHz. The voltage that is modulated to double the power-line frequency is supplied via an HF inductive resistor and via an ignition transmitter to the lamp, which is preferably filled with xenon to a pressure exceeding 1 ba r. The savings in electric energy for the system lamp ballast is equal to 30 % compared to a choke-operated Hg-free standard lamp having the same luminous flux. The use of a microprocessor for controlling the half bridge enables an externally controlled or automatic power reduction with an additional potential of savings in electric energy equal to an annual mean of 35 % and enables an end of life shutdown of the system in order to prevent cycling.