ABB PR121/P LSIG Electronic Overcurrent Release

Overview

The ABB PR121/P LSIG is an electronic overcurrent protection release designed for ABB SACE Emax E1 to E6 series air circuit breakers. The ABB PR121/P LSIG integrates four protection functions including long time delay overload protection, short time delay short circuit protection, instantaneous short circuit protection and ground fault protection. It provides adjustable current and time setting parameters for low voltage main distribution protection and can be matched with fixed or withdrawable Emax circuit breakers. The ABB PR121/P LSIG is widely used as spare replacement for power distribution cabinets in industrial plants, buildings and power stations.

Features

The ABB PR121/P LSIG supports independent setting of L, S, I and G protection thresholds and time delays to coordinate selective protection in multi-level distribution systems. It has built-in current measurement and fault memory function to record trip cause and fault current value for troubleshooting. The ABB PR121/P LSIG adopts front panel dip switches and adjustment knobs for on-site parameter setting without extra configuration software. It carries IEC and UL standard approvals and supports self-diagnosis for internal hardware failure and current transformer abnormality. The ABB PR121/P LSIG uses plug-in installation structure and matches the original breaker interface for direct replacement.

Specs

Device Type: Electronic overcurrent release Model: ABB PR121/P LSIG Protection Functions: L long time overload, S short time short circuit, I instantaneous short circuit, G ground fault Applicable Breaker: SACE Emax E1, E2, E3, E4, E5, E6 Setting Method: Front panel adjustable switches and potentiometers Diagnosis: Self-test, fault trip memory Power Supply: Powered by built-in current transformer Mounting: Front plug-in on Emax breaker Application: Low voltage main switch, distribution protection, MCC main incoming feeder

Principle

The ABB PR121/P LSIG samples three-phase current and neutral current signals from the current transformers inside the circuit breaker. The internal electronic circuit calculates the measured current value and compares it with preset protection thresholds. When overload, short circuit or ground fault occurs, the ABB PR121/P LSIG outputs trip signal to the breaker opening mechanism according to the selected time delay curve. The release keeps fault data stored after tripping and triggers self-fault alarm when internal circuit abnormality is detected.

Applications

The ABB PR121/P LSIG is used for main incoming and bus tie protection of low voltage distribution cabinets in factory power rooms and commercial buildings. It serves selective protection for large motor feeders and heavy load distribution loops. The ABB PR121/P LSIG applies to spare stock and field replacement of existing Emax air circuit breaker protection units. It also supports renovation and protection coordination adjustment of old low voltage power distribution systems.