Abstract: An abnormality detection circuit detects abnormality relating to ground fault in secondary winding circuitry of transformer, non-grounding fault of transformer assembly casing or false connection of the AC power source to the transformer assembly in reverse polarity. An interrupter circuit turns a switch off in response to detection of the abnormality by the abnormality detection circuit to interrupt the supply of the AC power to the transformer. When the supply of the AC power is interrupted, the switch is connected to a restart circuit, whereupon the circuit is activated to allow a charging current to flow to a capacitor, which is connected in series in a drive current path of a drive circuit with a time delay on the order of 0.5 to 1.0 second which is determined by a delay circuit thereof. The charging current drives a restoring circuit, which controls the interrupter circuit to its restoring condition temporally so that the switch is turned to its “on” condition only once.

Abstract: A step-up transformer is disposed on a wiring substrate 51 on which an inverter which converts a commercial a.c. power into a high frequency power and a ground fault detection circuit are mounted and within a casing 52. Lead wires 53, 54 which extend from the opposite ends of the secondary winding of the step-up transformer to the outside thereof are mounted upright on the wiring substrate 51. Coils 57, 58 are disposed on air-core bobbins 55, 56, which are threaded by the lead wires 53, 54. Outputs from the coils 57, 58 are fed to a ground fault detection circuit.

Abstract: An abnormality detection circuit 22 delivers a detected abnormality relating to a transformer 11. An interrupter circuit 23 turns a switch 16 off to interrupt the supply of the power to the transformer 11. When the supply of the power is interrupted, the switch 16 is connected to a restart circuit 31, whereupon the circuit 31 is activated to allow a charging current to flow to a capacitor, which is connected in series in a drive current path of a drive circuit 32 with a time delay on the order of 0.5 to 1.0 second which is determined by a delay circuit thereof. The charging current drives a restoring circuit 33, which controls the interrupter circuit 23 so that the switch 16 is turned on.

Abstract: A step-up transformer is disposed on a wiring substrate 51 on which an inverter which converts a commercial a.c. power into a high frequency power and a ground fault detection circuit are mounted and within a casing 52. Lead wires 53, 54 which extend from the opposite ends of the secondary winding of the step-up transformer to the outside thereof are mounted upright on the wiring substrate 51. Coils 57, 58 are disposed on air-core bobbins 55, 56, which are threaded by the lead wires 53, 54. Outputs from the coils 57, 58 are fed to a ground fault detection circuit.

Abstract: DC power is converted by an inverter to high-frequency power, which is supplied to the primary winding of a neon transformer. One or more neon tubes are connected in series across the secondary winding of the neon transformer. A saturable reactor is connected across the secondary winding or the neon transformer. The saturable reactor has a characteristic that its magnetic flux is saturated when the output voltage from the secondary winding of the neon transformer increases 1.1 to 2.0 times the rated voltage.