The Type SC line of relays are adjustable over a wide range of current. Each relay is provided with a mechanical operation indicator and a calibrated scale to indicate the pick-up setting.
The high drop-out to pick-up ratio (85-98%) of the Type SC relays make them particularly suitable for use as fault detectors to supervise main protective relays.
The Type SC-1 has a lower ration of drop-out to pick-up. This lower ratio makes possible a plunger pull characteristic which permits operation of a latching device.
These relays must not be used in critical applications where they may be pick-up for prolonged periods of time.