SCHNEIDER ELECTRIC S141A

Overview

SCHNEIDER ELECTRIC S141A is the Micrologic 3.0A electronic trip unit (UL/ANSI version) for Square D PowerPacT P/R frame and Masterpact NT/NW air circuit breakers. SCHNEIDER ELECTRIC S141A provides LI protection function plus built-in ammeter reading capability, it is a field-replaceable spare release assembly for low voltage power distribution breakers. SCHNEIDER ELECTRIC S141A is widely supplied as exchange spare for North American specification switchgear overhaul and breaker upgrade projects.

Features

SCHNEIDER ELECTRIC S141A supports L long-time overload protection and I instantaneous short-circuit protection, without short-time delay (S) and ground fault (G) function. It integrates current sensing and measurement circuit for local ammeter display of phase current values. SCHNEIDER ELECTRIC S141A uses interchangeable rating plug to set the long-time pickup current, convenient for on-site current range adjustment and breaker upgrade. It is self-powered from breaker CTs, no external auxiliary power supply required for normal protection action. SCHNEIDER ELECTRIC S141A includes internal hardware self-diagnosis; it will flag CT circuit failure or internal electronic anomaly to avoid missing faults or unwanted mis-trip. Compared with higher models S143A (5.0A LSI) and S144A (6.0A LSIG), this unit is for simpler LI protection applications. It complies with UL and CSA standards for North American market distribution equipment.

Specs

SCHNEIDER ELECTRIC S141A Trip unit type: Micrologic 3.0A. Protection function: LI (Long-time + Instantaneous). Extra function: integrated ammeter. Compatibility: PowerPacT P-frame, R-frame; Masterpact NT / NW. Standard: UL/ANSI. Setting method: matching rating plug. It is not a complete breaker; it must be installed into the matched breaker frame with current sensors. SCHNEIDER ELECTRIC S141A is widely supplied as service replacement spare for MCC and main distribution switchgear maintenanceSchneider ....

Principle

SCHNEIDER ELECTRIC S141A continuously samples phase current signals from the breaker CTs. The internal microprocessor calculates load current and compares it against the long-time and instantaneous thresholds set by the rating plug. When overload or short-circuit exceeds the limit, the trip unit triggers the breaker mechanical release mechanism to open contacts and isolate the fault circuit. The current measurement value of SCHNEIDER ELECTRIC S141A can be read locally via the trip unit display. If CT loss or internal electronics fault is detected, the unit raises a hardware alarm without unnecessary tripping.

Applications

SCHNEIDER ELECTRIC S141A is deployed for pumps, fans, general feeder and branch circuit protection in North American spec industrial plants, commercial facilities and data center low voltage distribution switchgear. It is selected for spare inventory and breaker retrofit projects where only LI overload and instantaneous short-circuit protection plus local current indication are required. It is the basic electronic release for Square D PowerPacT and Masterpact series breakers under ANSI system.