ABB SACE PR121/P-LSI PR121/P Electronic Trip Unit, LSI Three-stage Protection

Overview

The ABB SACE PR121/P-LSI is a basic electronic overcurrent release for SACE Emax air circuit breakers. It provides LSI three-stage protection: long-time overload, short-time selective short-circuit and instantaneous short-circuit trip, widely stocked as spare for main power distribution switchgear.

Features This PR121/P release has adjustable current thresholds and time delay curves for coordination. The PR121/P-LSI is equipped with LED fault indication, can be installed inside E1/E2/E3/E4 Emax ACB frames and replaced individually. It supports basic local protection without communication function.

Specs

Model: PR121/P-LSI Series: SACE Emax trip unit Type: electronic LSI overcurrent release Protection: L (overload), S (short-time), I (instantaneous) Applicable breaker: Emax E1, E2, E3, E4 Mounting: internal fit inside ACB Protection class: IP20 Certifications: CE, IEC 60947-2 Product status: switchgear spare

Principle

The trip unit samples three-phase current signals continuously. It triggers long-time delay trip for sustained overload, short-time delay for selective short-circuit and instant trip for severe short-circuit fault. It shows trip type via front LEDs.

Applications

The PR121/P-LSI is widely deployed in industrial substations, power plants and refinery main switchrooms. It is used for selective protection of ABB SACE Emax air circuit breakers.