ABB SPAU 121 C OVERVOLTAGE AND UNDERVOLTAGE PROTECTION RELAY

ABB SPAU 121 C is a single-phase combined overvoltage & undervoltage numerical protection relay from ABB legacy SPACOM series, discontinued since 2009ABB Group。This voltage monitoring relay is connected to voltage transformers, measuring phase-to-phase voltage for medium/low voltage distribution networks. This protection relay has independent overvoltage stage and undervoltage stage, both configurable for definite time or inverse time characteristic. It supports external blocking input for undervoltage function, and auto-blocking undervoltage stage when energizing supply is losteero. It is equipped with local display, serial communication and fibre-optic substation bus interface, with built-in hardware self-monitoring and fault diagnosis function.

This unit is a vital power distribution spare part for industrial, marine and substation switchgear overhaul. The power protection spare part monitors system voltage continuously. When voltage exceeds overvoltage threshold or drops below undervoltage setting, it triggers relay output for alarm, circuit breaker tripping or load shedding. The power protection spare part supports flexible parameter setting and fault event recording. It can replace old relay to restore voltage supervision and protection logic.

It delivers reliable system voltage monitoring & protective tripping control for power distribution systems. The system voltage monitoring & protective tripping control detects abnormal voltage deviation and executes time-delayed protection action. The system voltage monitoring & protective tripping control prevents equipment damage caused by overvoltage or undervoltage for transformers, generators and motor loads. The system voltage monitoring & protective tripping control sends fault records to SCADA for troubleshooting.

SPAU121C is panel-mounted inside substation or marine switchboard compartment. It is original ABB SPACOM voltage protection relay for legacy power network supervision.