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.
The protection relay is provided with energizing inputs for conventional current and voltage transformers. Also a hardware version with inputs for current and voltage sensors is available.
The REX 521 Feeder Protection Relay has been further enriched with additional features to provide your electrical network with even more efficient protection, extended measuring functions, supervision, control functions and connectivity. The REX 521 is mainly used in single busbar solutions, using one circuit breaker for various protections.
With pre-made, standard configurations the unit can be used in different types of networks and the typical applications include incoming and outgoing feeders in radial isolated neutral, resonant earthed, solidly earthed and resistively earthed systems.