The feeder protection relay REX 521 is designed for protection, control, measuring and supervision in medium voltage networks and for protection of large or medium-size three-phase a.c. motors in circuit breaker controlled motor drives. Typical applications include incoming, outgoing feeders and motor feeders as well as substation protection. Further, the relay can, e.g., be applied as back-up protection of power transformers and back up for high-voltage line-protection relays.
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