| | | Improves operational and personnel safety Supports your target of supplying high-quality power Enables preventive maintenance and shorter outage times, adding value to your asset management Large display for comfortable local operations Selectable IEC and ANSI symbols Flexible connectivity and IEC 61850 support | | |
| | | The REX 521 is the ultimate feeder protection relay for your distribution network. The relay is also a multifunction motor protection relay, a transformer protection relay and a constituent of your substation's busbar protection system. The smoothly communicating REX 521 relay integrates smoothly with the control and management system of your distribution network. | | Enhanced feeder protection The REX 521 relay is primarily employed in distribution substations to provide short-circuit, overcurrent and earth-fault protection as well as auto-reclosing of substation feeders. The relay can be used in isolated neutral, resonant earthed, solidly earthed and resis-tively earthed distribution networks. The sophisticated thermal overload function, the start-up supervision function and the und-ervoltage function also make the relay an ideal choice forthe protection of medium-sized and large circuit-breaker controlled AC motors. Further, the inrush current stabilization function allows the relay to be used for back-up protection of power transformers and for main protection of distribution transformers. The REX 521 relay has also been further developed to provide cost-effective busbar protection. Complete solution REX 521 complements ABB's solution for power system protection, control, measurement and supervision, now ranging from basic protection relays to advanced feeder | | protection and bay control terminals. The REX 521 relay offers a comprehensive set of feeder protection functions enhanced with supervision functions such as, for instance, power quality supervision. Support for current sensors type Rogowski coils and voltage dividers are also available. Advanced data collection and analysis functions contribute to improving the efficiency ofyour network control, maintenance and management operations. Improved system availability and safety The REX 521 relay features condition monitoring of both primary and secondary systems of the substation as well as of the device itself. The monitoring adds to the operational reliability ofthe protection, which considerably improves personnel safety. Personnel safety has also been improved by enabling delayed circuit breaker closing when the circuit breaker is controlled locally via the HMI. The CB closing delay is adjustable but can also be set to zero for immediate CB control response. | | |