ELECTRIC MOTOR SHORT CIRCUIT PROTECTION OVERVIEW How are electric motors protcted from short circuits? A short circuit is a direct contact between two points of different electric potential: 1. Alternating current: phase-to-phase contact, phase-to-neutral contact, phase-to-ground contact or contact between windings in a phase. 2. Direct current: contact between two poles or between the ground and the pole insulated from it. This can have a number of causes: damage to the varnish insulating the conductors, loose, broken or stripped wires or cables, metal foreign bodies, conducting deposits (dust, moisture, etc.), seepage of water or other conducting fluids, wrong wiring in assembly or maintenance. A short circuit results in a sudden surge of current which can reach several hundred times the working current within milliseconds. A short circuit can have devastating effects and severely damage equipment. It is typified by two phenomena. A thermal phenomenon A thermal phenomenon co...