Schneider Electric MT Series Air Circuit Breakers — MT12N1

Technical Dossier

Product Details And Specifications

Schneider Electric MT Series: Comprehensive Module Range and Technical Overview

The Schneider Electric (formerly Merlin Gerin) MT Series air circuit breakers represent a foundational product line deployed across global heavy industry, including petrochemical refineries, nuclear power generation facilities, offshore platforms, and large-scale chemical processing plants. Rated for low-voltage power distribution panels operating at up to 690V AC, the MT Series established the benchmark for molded-case and open-frame air circuit breaker design in European and Asian industrial markets from the 1980s onward. Installations of MT Series breakers remain active in legacy switchgear assemblies worldwide, making reliable spare parts sourcing a critical operational requirement for plant maintenance engineers and MRO procurement teams.

The Evolution of MT Series Architecture

The MT Series was introduced under the Merlin Gerin brand, which Schneider Electric fully absorbed following its 1992 acquisition. Early MT variants — including the MT06, MT08, and MT10 — were designed for fixed-mount panel applications with manual operation and thermal-magnetic trip mechanisms. These units featured a standardized DIN-rail-compatible footprint and plug-in terminal blocks that allowed field replacement without rewiring the downstream circuit.

Through the 1990s, Schneider expanded the MT Series to include motorized versions (suffix M), remote-reset variants, and models with integrated auxiliary contacts for supervisory control integration. The architecture remained backward-compatible across frame sizes, allowing MT12 to replace MT10 in most panel configurations without mechanical modification.

By the mid-2000s, the MT Series entered its maturity phase as Schneider introduced the Compact NS and EasyPact MVS lines as forward-compatible successors. However, the MT Series was not formally discontinued in all markets simultaneously — regional stocking continued in Asia-Pacific and Middle Eastern markets well into the 2010s. As of 2026, the MT Series is classified as a legacy/end-of-life product line. Schneider Electric no longer manufactures MT Series units; however, certified refurbished stock and new-old-stock (NOS) units remain available through specialist distributors such as DriveKNMS.

MT Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced models within the Schneider Electric MT Series. Each unit is classified by its primary function within a low-voltage power distribution or motor control assembly.

MT06N1: 3-pole MCCB, 63A frame, thermal-magnetic trip, fixed mount
MT06N2: 3-pole MCCB, 63A frame, thermal-magnetic trip, plug-in mount
MT08N1: 3-pole MCCB, 80A frame, adjustable thermal trip, fixed mount
MT08N2: 3-pole MCCB, 80A frame, adjustable thermal trip, plug-in mount
MT10N1: 3-pole MCCB, 100A frame, thermal-magnetic trip, fixed mount
MT10N2: 3-pole MCCB, 100A frame, thermal-magnetic trip, plug-in mount
MT12N1: 3-pole MCCB, 125A frame, thermal-magnetic trip, fixed mount — primary SKU of this listing
MT12N2: 3-pole MCCB, 125A frame, thermal-magnetic trip, plug-in mount
MT16N1: 3-pole MCCB, 160A frame, adjustable thermal-magnetic trip, fixed mount
MT16N2: 3-pole MCCB, 160A frame, adjustable thermal-magnetic trip, plug-in mount
MT20N1: 3-pole MCCB, 200A frame, electronic trip unit, fixed mount
MT25N1: 3-pole MCCB, 250A frame, electronic trip unit, fixed mount
MT32N1: 3-pole MCCB, 320A frame, electronic trip unit, fixed mount
MT40N1: 3-pole MCCB, 400A frame, electronic trip unit, fixed mount
MT06M1: 3-pole MCCB, 63A frame, motorized operation, fixed mount
MT10M1: 3-pole MCCB, 100A frame, motorized operation, fixed mount
MT12M1: 3-pole MCCB, 125A frame, motorized operation, fixed mount
MT16M1: 3-pole MCCB, 160A frame, motorized operation, fixed mount
MT20M1: 3-pole MCCB, 200A frame, motorized operation, fixed mount

Sourcing Hard-to-Find & Obsolete MT Series Parts

DriveKNMS maintains a dedicated inventory program for end-of-life Schneider Electric MT Series circuit breakers. As Schneider Electric has transitioned its product roadmap to the Compact NS and EasyPact series, OEM supply channels for MT Series units have been formally closed. Plant operators running legacy switchgear panels face a binary choice: full panel replacement — a capital-intensive project requiring extended downtime — or sourcing certified replacement units from specialist MRO distributors.

DriveKNMS sources MT Series stock through a global network of decommissioned plant equipment, authorized surplus dealers, and factory-sealed NOS inventory. All units are cataloged by frame size, trip rating, mounting type, and auxiliary contact configuration. Customers requiring specific trip curve settings (B, C, D) or custom auxiliary contact arrangements (OF, SD, MX) can submit detailed specifications for cross-reference matching against available stock.

For plant maintenance teams operating under ISO 55000 asset management frameworks, DriveKNMS provides documentation packages including test certificates, traceability records, and condition reports to support internal compliance requirements.

Quality Control for the MT Series Range

Each MT Series unit processed by DriveKNMS undergoes a structured inspection and functional test protocol prior to dispatch. The procedure addresses the specific failure modes associated with aged thermal-magnetic trip mechanisms and degraded arc-quenching chambers common in long-stored or field-recovered units.

Inspection stages include: visual examination of the molded case for cracking, contact erosion measurement against OEM wear limits, insulation resistance testing at 500V DC between poles and between poles and frame, mechanical operation cycling (minimum 5 open/close cycles under no-load), and trip function verification using a calibrated injection test set to confirm trip current thresholds within ±10% of nameplate rating. Motorized variants (suffix M) additionally undergo actuator torque testing and control circuit continuity verification at rated control voltage (110V AC or 24V DC as applicable). Units failing any stage are quarantined and not offered for sale.