Patent ID: 6504691
Filing Date: 2003-01-07
Classification: H02H,H05B

Abstract:
A ground fault protective circuit for detecting a ground connection of a wiring or a load in circuits of secondary windings of a neon transformer, comprising;a first and a second input terminal to which an AC power supply is connected; a ground fault voltage detection circuit connected between a neutral point of the secondary windings and a ground terminal of the transformer which is non-responsive to a normal voltage appearing at the neutral point with respect to a ground potential at the ground terminal when the transformer is operated in a normal condition but is responsive to a fault voltage appearing at the neutral point and exceeding the normal voltage when the transformer is operated in an abnormal condition due to occurrence of said ground connection for generating a fault detection output indicating the occurrence of the ground connection in response to the fault voltage; and a power supply interrupter connected between the first and second input terminals and opposite ends of a primary winding of the transformer and controlled by the fault detection output from the ground fault voltage detection circuit to interrupt the supply of the AC power from the AC power supply to the primary winding, wherein said normal voltage appearing at the neutral point when the transformer is operated in the normal condition is close to the ground potential.