PROTECTIVE CIRCUIT OF STABILIZER EQUIPMENT TO DETECT RECTIFICATION OF ARC DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To protect a lamp and installation parts from overheating by detecting a DC voltage caused at both ends of the lamp when the lamp approaches the end of its life. SOLUTION: A ballast contains a circuit to observe the state of each cathode by measuring a DC component. An inverter is put out of action to prevent excessive overheating in the cathode after an expected increase of the DC component. The inverter is also put out of action as a result of the state of the resonance mode or near-resonance mode of a tank circuit caused by open circuit conditions or a leakage current.