Gas discharge device power supply with ground fault protection

摘要

A gas discharge device, such as a neon tube, is connected to a pair of output terminals of a power supply. The power supply has a transformer with a secondary winding that has first and second sub-windings. Each of the sub-winding is connected to a different output terminal and two conductors connect the first and second sub-windings to earth ground. A current sensor detects whether unequal magnitudes of current flow through in the two conductors. A resonant control circuit applies an excitation current to the primary winding of the transformer unless an imbalance of current flows. Thus excitation of the transformer is terminated when a high voltage ground fault occurs.