Patent ID: 7660083

Claim:
An electromechanical/solid-state alternating-current (AC) relay comprising: an AC input that receives a continuous alternating-current signal; a control input that indicates a turn-on state and a turn-off state; an AC output that outputs an AC signal in response to the control input being in the turn-on state; mechanical contacts coupled between the AC input and the AC output; a movable arm that moves the mechanical contacts into a closed position that connects the AC input to the AC output, and that moves the mechanical contacts into an open position that disconnects the AC input from the AC output an AC common line; a winding coil that generates an electromagnetic force that moves the movable arm; a driver circuit, receiving a relay signal, that drives current through the winding coil in response to the relay signal; a triac coupled between the AC input and the AC output in parallel with the mechanical contacts, the triac having a gate input; a zero-sampling circuit coupled to the AC input, for generating a zero-crossing signal when the AC input switches direction of current flow; and a control circuit, responsive to the control input and receiving the zero-crossing signal, for driving an activating signal onto the gate input of the triac when the zero-crossing signal indicates detection of the AC input switching direction of current flow after the control input switches into the turn-on state, and for activating the relay signal to the driver circuit so that the mechanical contacts move into the closed position after the triac is activated to conduct current to the AC output wherein the zero-sampling circuit comprises: a zero-detect capacitor coupled between the AC input and a zero-crossing signal input to the control circuit; and a zero-detect resistor coupled between the zero-crossing signal input to the control circuit and the AC common line; wherein the control circuit drives a de-activating signal onto the gate input of the triac after the mechanical contacts have moved into the closed position, whereby arcing across the mechanical contacts when moving into the closed position is prevented by first activating the triac when the AC input switches direction of current flow.