Schneider MICROLOGIC Electronic Trip Unit

Module Feature

MICROLOGIC is a series of replaceable electronic trip units developed by Schneider Electric for ComPacT NSX and Masterpact MTZ circuit breakers.

Multiple variants are available, including basic models without display and advanced versions with LCD screen. It supports long-time overload, short-time delay, instantaneous short-circuit and optional earth leakage protection. High-end versions integrate power measurement, energy metering, event recording and network communication functions. It can be configured locally via front knobs or PC software. Widely stocked as spare for industrial low voltage power distribution cabinet.

Working principle

Current sensors inside the breaker feed three-phase current signals to the trip unit.

The built-in microprocessor compares measured current with preset protection thresholds. When abnormal current exceeds setting, the unit sends trigger signal to the breaker trip mechanism to cut off the circuit. It continuously records electrical parameters and fault events for power monitoring and selective coordination.

Onboard components

Signal acquisition circuit, microprocessor, setting knob or LCD panel, status LED array, trip trigger output, communication interface and plastic housing.

LED indicators

Front LEDs indicate power ready, overload pre-alarm, fault trip and earth leakage alarm status.

Hardware self‑diagnosis

Internal self-check monitors sensor signal, power supply and trip circuit health. Protection parameters can be adjusted on panel or via software.

Programming software

EcoStruxure Power Commission / Ecoreach, used for protection setting, metering configuration, fault log reading and firmware upgrade.

Electrical & Process Parameters

Model: MICROLOGIC Brand: Schneider Electric Device type: Electronic trip control unit Function: Overload, short-circuit and earth fault protection, power measurement for low voltage distribution circuit

Mechanical & Structure

Mounting: Insert mounting inside NSX / MTZ MCCB Protection class: IP40 (front panel) Housing: Flame retardant reinforced plastic

Environmental

Operating temperature: -25℃ ~ +70℃ Storage temperature: -40℃ ~ +85℃ Ambient humidity: 5~95% non‑condensing

Certification: CE Status: Original Schneider electrical spare

Installation

Cut off upstream power supply before replacement.

Insert trip unit into the breaker base, lock the fixing buckle, set protection parameters, test trip function and communication after commissioning.

Interface

Current sensor connector, trip drive output, auxiliary communication port, test button.

Diagnostic

Overload trip: Load current exceeds Ir setting, poor heat dissipation. Short-time trip: Fault current exceeds Isd setting, coordination mismatch. No communication: Wiring loose, address or protocol setting error.

Product Brief

MICROLOGIC unit, Schneider replaceable electronic trip control unit spare for NSX and MTZ moulded case circuit breaker protection and metering replacement.