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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.

SEL-501 Dual Universal Overcurrent Relay

The SEL-501 Dual Universal Overcurrent Relay provides two complete and independent groups of protection functions in one compact unit. The unit contains Relay X and Relay Y, each having separate optoisolated inputs, output contacts, and three-phase current inputs.