Frequency Protection Relays

Frequency protection relays continuously monitor the frequency of AC supplies, tripping upon fault condition. The output relay trips when the monitored frequency is outside of the user adjustable limit and the LED illuminates indicating a fault condition. The trip point on all models (except the B851C) is adjustable from 1Hz to 5Hz through the front control knob. The output relay is set to de-energise in the under frequency condition ensuring the protection relays are failsafe. The relays are self powered, requiring no auxiliary power supply and are available with either a single or double pole changeover relay output and optional built-in time delay.

Key Terms: B851 - B851A - B851B - B851C - TA851 - Frequency - Protection Relay