Switching circuit, typically for lighting relay, with first and second switches actuated by respective actuating signals and periodic gating signals

摘要

switching circuit 10 comprises: a) an electrically actuatable first switching device 17 which is arranged to be connected in series with an active conductor 14, 15 and a load 11 in a single phase ac circuit; b) a solid state second switching device 18 connected in series with the first switching device; and c) a control circuit 19 including an energy storage device (capacitors 22, 23) connected across the second switching device 18 and, also, across both the first and the second switching devices. The control circuit 19 is arranged to apply actuating signals to the first switching device 17 and to apply periodic gating signals to the second switching device 18 in a manner to cause a predetermined voltage rise across the second switching device 18 sufficient to effect charge replenishment in the energy storage device when the first switching device 17 is in a conducting state. The first switching device may comprise an electromagnetic relay having a coil 21 to which actuating/latching current is fed by way of the energy storage device. The second switching device may comprise a low impedance solid state switching device.