Abb manufactures and supplies directional earth fault relay and feeder protection relays. The spas 348 c, a feeder protection relay is used for application requiring directional phase over current, directional short-circuit and directional earth-fault protection of infeeders and busbars in distribution substations provided with multiple infeeders supplied via power transformers from the same high-voltage busbar system. Salient features are as follows: 1 the relays are also applied for the selective short-circuit and earth-fault protection of parallel multiple feeders between substations and for feeder protection in ring-type and meshed distribution networks. 2 the directional relays are used for the protection of radial feeders supplied with a small back-feed of energy from a generator in the consumer-end of the feeder.
