ABB PR122/P-LSIG

Overview

ABB PR122/P-LSIG is a digital overcurrent release for the ABB SACE Emax E1 to E6 series air circuit breaker (ACB). LSIG stands for Long-time, Short-time, Instantaneous and Ground-fault protection functions. This release is still widely used in low-voltage main switchboards and power distribution systems, and it is commonly supplied as exchange spare for Emax cabinet maintenance and breaker retrofit.

Features

ABB PR122/P-LSIG provides fully adjustable protection curves for long-time overload, short-time delayed short circuit, instantaneous short circuit and ground fault. Each protection parameter can be configured locally via the front LCD keypad or remotely through communication. It supports selective coordination planning between upstream and downstream protective devices to limit unnecessary blackouts during faults. ABB PR122/P-LSIG integrates built-in metering functions for phase current, voltage, power, energy and demand values, eliminating separate power meter hardware in many distribution panels. It records timestamped fault logs, trip waveforms and event history for post-fault analysis. ABB PR122/P-LSIG supports Modbus-RTU communication for connection to PLC, SCADA and power monitoring systems. The front panel LCD and LED indicators show real-time readings, alarm status and trip cause for quick on-site troubleshooting. It is powered by the built-in current transformers of the breaker, so basic protection remains functional even when control auxiliary power is lost. It complies with IEC 60947-2 and relevant low-voltage standards.

Specs

ABB PR122/P-LSIG Platform: SACE Emax E1 / E2 / E3 / E4 / E5 / E6 air circuit breaker. Type: digital LSIG trip unit. Protection: L (overload), S (short-time), I (instantaneous), G (ground fault). Communication: Modbus RTU. Display: LCD with keypad. Power source: self-powered from breaker CTs. This is not a complete circuit breaker; it is the electronic trip release assembly for Emax ACB. ABB PR122/P-LSIG is widely supplied as service replacement spare for failed trip units.

Principle

ABB PR122/P-LSIG samples current signals from the breaker’s internal CTs continuously. The internal microcontroller compares measured current against the preset protection thresholds. When overload persists beyond the long-time curve setting, the release sends a trip signal to open the ACB. Short-time and instantaneous functions respond faster for high-magnitude short-circuit events, while ground fault protection detects residual current from earth leakage. The metering and logging functions of ABB PR122/P-LSIG store fault snapshots and transmit operating data over Modbus for remote power management and alarm logging.

Applications

ABB PR122/P-LSIG is deployed on main incoming breakers, bus tie breakers and large motor feeder breakers in industrial plants, data centers, commercial buildings, hospitals and marine low-voltage switchrooms. It is selected for spare inventory and panel upgrade projects for existing Emax E1-E6 air circuit breakers.