The Type CEX57 is a family of high-speed induction cup relays with angle impedance characteristics that can be set parallel to the impedance characteristic of a protected line. Generally, these relays are meant to be used with other pro-tective relays in blinder applications restrict the tripping zone of a scheme they may be used in applications that require tripping for out-of-step conditions. These are a single-phase relays that includes two ohm units with opposite polarity and may also include an auxiliary telephone type unit.
The Type GSY51 relay includes a mho distance unit with reverse offset, six auxiliary telephone units and a target-seal in unit all mounted in one drawout case. This relay is intended for use with the CEX57E angle impedance relay to provide out-of-step protection for a generator.