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➤ Breaker failure protection for each terminal integrates bus ➤ Differential protection is secure for external faults with ➤ Differential protection accommodates as high as 10:1 CT ratio Shorted CTs for alarming and/or blocking. ➤ Failed CT detection elements reliably indicate open and

Protection for multiple busbar applications. ➤ Flexible zone selection and six differential zones provide To increase system stability margins andreduce equipment ➤ Busbar differential protection operates in less than one cycle SELResearch and Development for methods on protecting larger Six independent and adaptable zones of protection. Terminals, use three SEL-487Brelays each relay provides as many as Forbuses with no more than seven terminals, use one The relay has 21 analog current inputs and three analog The SEL-487B Relay provides bus current differential protection,Ĭircuit breaker failure protection, andbackup overcurrent SEL-487B Dataīusbar and Breaker Failure Protection,Automation, and Control Schweitzer Engineering Laboratories, Inc. ➤ Interconnection with automation systems uses IEC 61850 or DNP3 protocols directly or DNP3 through a Communications Processor. ➤ Three dedicated check zones are available in each relay to supervise complex bus differential schemes.

➤ Negative- and zero-sequence over- and undervoltage elements provide for differential element supervi- sion. ➤ Instantaneous and inverse time-overcurrent elements provide backup protection for each terminal. ➤ Breaker failure protection for each terminal integrates bus and breaker failure protection. ➤ Differential protection is secure for external faults with minimal CT requirements. ➤ Differential protection accommodates as high as 10:1 CT ratio mismatch without auxiliary CTs. ➤ Failed CT detection elements reliably indicate open and shorted CTs for alarming and/or blocking. ➤ Flexible zone selection and six differential zones provide protection for multiple busbar applications. ➤ Busbar differential protection operates in less than one cycle to increase system stability margins and reduce equipment damage. Contact SEL Research and Development for methods on protecting larger systems. For buses with as many as 21 terminals, use three SEL-487B relays each relay provides as many as six independent and adaptable zones of protection. For buses with eight to ten terminals, use two SEL-487B relays.

For buses with no more than seven terminals, use one SEL-487B in a single-relay application. The relay has 21 analog current inputs and three analog voltage inputs. SEL-487B Data Sheet Busbar and Breaker Failure Protection, Automation, and Control System Major Features and Benefits The SEL-487B Relay provides bus current differential protection, circuit breaker failure protection, and backup overcurrent protection.