Patent ID: 8547673

Claim:
An electrical switching apparatus comprising: a first terminal; a second terminal; a neutral conductor; separable contacts electrically connected between said first terminal and said second terminal; an operating mechanism structured to open and close said separable contacts; a first fused varistor electrically connected between said first terminal and said neutral conductor; a trip mechanism cooperating with said operating mechanism to trip open said separable contacts, said trip mechanism comprising a trip coil; a second varistor electrically connected in series with the trip coil between said first terminal and said neutral conductor; a thyristor electrically connected in parallel with said second varistor; and an overvoltage detection circuit electrically interconnected with said thyristor, said overvoltage detection circuit being structured to cause said thyristor to energize said trip coil and cause said trip mechanism to trip open said separable contacts responsive to overvoltage between said first terminal and said neutral conductor, wherein said first fused varistor comprises a fuse electrically connected in series with a varistor between said first terminal and said neutral conductor; wherein an overvoltage exists between said first terminal and said neutral conductor; wherein prior to said fuse being opened, said overvoltage detection circuit begins to conduct current; wherein said trip coil comprises a first node and a second node electrically connected to said neutral conductor; wherein said thyristor comprises a gate; and wherein said overvoltage detection circuit comprises a first resistor electrically connected between said first terminal and said gate, and a series combination of a resistor, a diode and a zener diode electrically connected between said gate and the first node of said trip coil.