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SEL-487B Bus Differential and Breaker Failure Relay

The SEL-487B provides optimized bus differential fault detection by using high-speed, subcycle protection coupled with high-security operation for external faults. Superior protection performance is combined with integrated station automation features for seamless transition into new and retrofit applications.

Breaker-Failure Protection Products

These breaker-failure schemes were designed within the limits of the prevailing technology, such as inaccurate timers with overtravel and slow-reset overcurrent elements. The development of microprocessor-based relaying, digital input filtering, and low-burden CT secondary circuits allows easier breaker-failure protection application with measurable gains in performance.