Patent ID: 7633737

Claim:
A fault-tolerant protection device for protecting electrical equipment, the fault-tolerant protection device comprising: a surge arrester connected in parallel to electrical equipment that has an impedance higher than an impedance of the electrical equipment at normal operating voltages and an impedance lower than an impedance of the electrical equipment at abnormally high voltages; a surge durable fuse element connected in series with the surge arrester, the surge durable fuse element being configured to melt and separate when exposed to excessive power frequency current flowing through the surge arrester; and arc shortening tabs coupled to the surge durable fuse element and forming a gap that is shorter than a distance between ends of the surge durable fuse element; wherein the surge durable fuse element and the surge arrester are immersed within a tank that is filled with fluid and that houses the electrical equipment, and the surge durable fuse element melts after approximately one cycle of exposure to an approximately 1250 Amp power frequency current.