SWITCHING CIRCUIT HAVING DELAY FOR INRUSH CURRENT PROTECTION

摘要

A two-wire switching circuit can handle a large inrush current, but does not require a neutral connection or a heavy-duty mechanical switch or relay. The switching circuit comprises a mechanical air-gap switch and a controllably conductive device, which are coupled in series and are adapted to be coupled between an AC power source and an electrical load when the mechanical switch is in a first position. A first delay circuit is coupled in parallel with the controllably conductive device and in series with the mechanical air-gap switch. A latching circuit, which is responsive to the first delay circuit, is coupled to the controllably conductive device for controlling the controllably conductive device. The first delay circuit causes the latching circuit to control the controllably conductive device to be conductive after a first predetermined time after the mechanical air-gap switch changes to the first position.