Schneider Electric MT Series Air Circuit Breakers: MT25N1

Technical Dossier

Product Details And Specifications

Schneider Electric MT Series Air Circuit Breakers: Comprehensive Module Range and Technical Overview

The Schneider Electric MT Series (marketed under the legacy Merlin Gerin brand) represents a foundational line of molded-case and air circuit breakers deployed across global heavy industry. MT Series units are installed in chemical processing plants, nuclear auxiliary power distribution panels, petroleum refinery MCC (Motor Control Center) switchgear, and offshore platform power distribution boards. Rated from 16 A to 1600 A depending on frame size, the MT Series covers thermal-magnetic and electronic trip unit configurations, making it a reference standard in IEC 60947-2 compliant low-voltage switchgear. The series remains one of the most widely specified breakers in legacy European and Asian industrial infrastructure built between the 1980s and 2010s.

The Evolution of MT Series Architecture

The MT Series originated from Merlin Gerin's Compact and Multi 9 platform families, later absorbed into Schneider Electric's unified circuit protection portfolio following the 1992 merger. Early MT frame variants (MT06, MT08, MT10) used bimetallic thermal-magnetic trip mechanisms with fixed calibration, offering no field adjustment. Mid-generation frames (MT16, MT25, MT32) introduced adjustable thermal and magnetic thresholds, enabling broader application flexibility across motor branch circuits and feeder protection. Late-generation variants incorporated electronic trip units (ETU) with Ir, Im, and Isd settings, compatible with Schneider's Micrologic trip unit ecosystem. Compatibility across generations is frame-specific: MT25 and MT32 share the same mounting footprint in many panel configurations, but trip unit cartridges are not interchangeable between thermal-magnetic and ETU variants. As of 2015, the MT Series entered the mature/end-of-life phase, with Schneider Electric transitioning customers to the EasyPact EZC and ComPact NSX lines. DriveKNMS maintains stock of MT Series units specifically to support long-term maintenance contracts on installed base equipment that cannot be cost-effectively retrofitted.

MT Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced MT Series part numbers. Each entry reflects the standard IEC-rated configuration. Ampere ratings, pole count, and trip unit type are encoded in the model designation.

MT06N1: 3-pole thermal-magnetic MCB, 6 A, fixed trip, DIN rail mount, IEC 60947-2.
MT08N1: 3-pole thermal-magnetic MCB, 8 A, fixed calibration, motor branch circuit protection.
MT10N1: 3-pole thermal-magnetic MCB, 10 A, standard breaking capacity 25 kA at 415 V.
MT16N1: 3-pole MCCB, 16 A, adjustable thermal trip, suitable for feeder and motor protection.
MT20N1: 3-pole MCCB, 20 A, thermal-magnetic, panel board and distribution board use.
MT25N1: 3-pole MCCB, 25 A, adjustable magnetic trip, IEC 60947-2, standard breaking 36 kA.
MT32N1: 3-pole MCCB, 32 A, thermal-magnetic, compatible with MT25 mounting footprint.
MT40N1: 3-pole MCCB, 40 A, adjustable Ir/Im settings, motor and feeder dual-use.
MT50N1: 3-pole MCCB, 50 A, thermal-magnetic trip, industrial distribution panel application.
MT63N1: 3-pole MCCB, 63 A, high breaking capacity variant, MCC incomer protection.
MT80N1: 3-pole MCCB, 80 A, electronic trip unit option available, switchboard feeder.
MT100N1: 3-pole MCCB, 100 A, Micrologic ETU compatible, adjustable Ir/Isd/Im.
MT125N1: 3-pole MCCB, 125 A, thermal-magnetic, main incomer for sub-distribution boards.
MT160N1: 3-pole MCCB, 160 A, high-performance frame, ETU and TM trip variants available.
MT250N1: 3-pole MCCB, 250 A, large frame, electronic trip, main distribution board incomer.
MT400N1: 3-pole ACB, 400 A, drawout or fixed mount, Micrologic 2.0/5.0/6.0 ETU.
MT630N1: 3-pole ACB, 630 A, bus bar connection, main LV switchboard incomer.
MT800N1: 3-pole ACB, 800 A, electronic trip, generator and transformer feeder protection.
MT1000N1: 3-pole ACB, 1000 A, drawout frame, main incomer for large industrial facilities.
MT1600N1: 3-pole ACB, 1600 A, maximum frame rating, primary distribution switchgear.

Sourcing Hard-to-Find & Obsolete MT Series Parts

The MT Series was officially discontinued for new orders in most markets by 2018. Schneider Electric no longer manufactures MT06 through MT63 frame variants, and spare trip unit cartridges for thermal-magnetic configurations are no longer available through standard distribution channels. DriveKNMS operates a dedicated obsolete parts inventory program for the MT Series, sourcing units from decommissioned plant equipment, certified refurbishers, and bonded warehouse stock across Europe and Asia. All units are inspected against original Schneider Electric factory specifications before dispatch. For end-users operating legacy switchgear panels where a like-for-like replacement is required to avoid full panel redesign, DriveKNMS provides the MT Series as a direct drop-in solution with full traceability documentation. Lead times for common ratings (MT25N1, MT32N1, MT63N1) are typically 3–7 business days from confirmed order.

Quality Control for the MT Series Range

MT Series circuit breakers incorporate complex bimetallic trip assemblies and, in higher-frame ETU variants, digital trip unit PCBs with CAN bus communication interfaces. DriveKNMS applies a multi-stage inspection protocol specific to this series: (1) Visual inspection of the molded case for arc damage, contact erosion indicators, and mechanical latch integrity. (2) Insulation resistance testing at 500 V DC between poles and between poles and frame, minimum 1 MΩ acceptance threshold. (3) Contact resistance measurement across each pole using a micro-ohmmeter; values exceeding 150% of factory specification trigger rejection. (4) Trip unit functional test: thermal trip verification at 1.05× and 1.35× In, magnetic trip verification at Im setting. (5) For ETU variants: communication interface test via RS485 or Modbus RTU to verify Micrologic parameter read/write integrity. (6) Mechanical endurance: minimum 50 open/close cycles under load simulation before dispatch approval. Each unit ships with a DriveKNMS inspection certificate referencing the applicable IEC 60947-2 test parameters.