Ground fault current is sensed by passing all lines carrying current to and from a motor through the window of a special current transformer called a ground fault sensor. If all of the current to the motor returns through the lines in the sensor window, no significant current will be induced in the sensor secondary. However, if ground fault current returns via a path external to the sensor, such as via the conduit walls, a current will be induced in the sensor secondary. This current will be sensed and amplified by solid state circuits. If the ground fault current is larger than the selected ground fault trip level of the overload relay, the overload relay will trip.
Typical applications of ground fault detection (protection) include dirty water or clean water treatment plants, wash down areas of industrial plants, pumping applications, and of course marine as well as mining applications.
For additional information please contact your nearest authorized distributor, sales representative, or call our customer service or technical support lines.