LMM1 Series Moulded Case Circuit Breaker (MCCB)

Product Overview

The LMM1 series moulded case circuit breaker is a core protection device for low-voltage 3-phase and 4-wire industrial distribution systems. It is installed as main incoming breaker, feeder breaker or motor protection breaker in distribution cabinets, switchgear assemblies and motor control centers, providing comprehensive protection against overload current, short-circuit fault and phase imbalance.

The series covers a rated current range from 63A to 1250A, with three breaking capacity grades (L, M, H) to match different system short-circuit levels and application scenarios. It adopts a proven thermal-magnetic trip mechanism: bimetallic strip provides inverse-time overload protection, and electromagnetic coil provides instantaneous short-circuit tripping. The compact moulded insulation housing ensures high dielectric strength and personal safety during operation. Compliant with IEC 60947-2 international standard, it is widely applied in manufacturing plants, commercial buildings, renewable energy systems, infrastructure and data center power distribution.

Key Product Features

✅ Wide Current Range & Multiple Breaking Grades Rated current from 63A to 1250A, available in L, M, H breaking capacity levels. Flexible selection according to system short-circuit current and protection requirements, covering light distribution to heavy-duty industrial scenarios.

✅ Thermal-Magnetic Dual Protection Bimetallic strip delivers inverse-time overload protection with ambient temperature compensation; electromagnetic coil delivers instantaneous short-circuit tripping. Accurate tripping characteristics, avoids false tripping and provides reliable circuit protection.

✅ 3P / 4P Configurations 3-pole for 3-phase 3-wire systems, 4-pole for 3-phase 4-wire systems with neutral pole switching. Suitable for TN, TT and IT grounding systems, meets various industrial distribution architecture requirements.

✅ Compact Moulded Insulation Housing Integrated flame-retardant moulded case, high dielectric strength and excellent arc quenching performance. Closed structure prevents direct contact with live parts, ensures operation safety and reduces arc hazard during fault interruption.

✅ Front Central Operating Handle Ergonomic front-mounted toggle handle with clear ON/OFF position indication. Red push-to-trip button for manual test and emergency trip. Intuitive operation for on-site commissioning and maintenance.

✅ Fixed Panel Mount Installation Standard panel mounting dimensions, suitable for fixed installation in distribution cabinets, MCC panels and switchgear assemblies. Standard terminal layout for easy busbar and cable connection.

✅ IEC 60947-2 International Standard Manufactured and tested in full compliance with IEC 60947-2 and GB/T 14048.2 standards. Passed full type test including breaking capacity, endurance and dielectric test, qualified for global industrial projects.

Technical Specifications

Note: Breaking capacity values vary by frame size and voltage level. Refer to product datasheet for detailed parameters of specific models.

Application Scenarios

• Industrial plant main distribution and sub-distribution panels
• Low-voltage switchgear assemblies and motor control centers (MCC)
• Commercial building and infrastructure main incoming protection
• Renewable energy (PV, wind) inverter and grid connection protection
• Data center and critical facility power distribution systems
• Pump, fan and motor feeder circuit protection

Our Advantages

1. Full range of frame sizes in stock Complete 63A to 1250A frame sizes and breaking grades in stock, support mixed batch orders for panel builders and switchgear manufacturers, with fast bulk shipment available.
2. Stable and accurate tripping performance Precision calibrated bimetallic strip and electromagnetic release mechanism, accurate tripping characteristics with temperature compensation, avoids nuisance tripping and ensures selective protection coordination.
3. Strict full type test verification Each model undergoes complete type testing including short-circuit breaking, overload endurance, dielectric withstand and mechanical life test before mass production, ensuring reliable on-site performance.
4. Standard mounting dimensions Industry-standard mounting footprint and terminal spacing, compatible with mainstream MCCB dimensions on the market. Can be directly installed in standard distribution cabinets without modification.
5. Complete project technical support Provide dimension drawings, wiring diagrams, selection guides and test certificates to support project design, tender bidding and type approval. Fast overseas technical response.

Custom Solution

We provide project-oriented custom solutions for LMM1 series MCCB:

• OEM Brand Customization: Custom silk-screen logo, rating label and model marking on product housing for distributor branded resale.
• Specification Customization: Custom trip settings, auxiliary contacts, shunt release, under-voltage release and other accessories according to project requirements.
• Terminal Configuration: Custom front / rear terminal, extended terminal and busbar connection options for switchgear assembly.
• Export-grade Custom Packing: Neutral carton, customer-branded packaging, seaworthy reinforced packing for long-distance sea transportation.
• Large-project Priority Production: Priority production and delivery schedule for large industrial and infrastructure project orders.

Share your required current rating, pole configuration, breaking capacity and auxiliary requirements, our engineers will recommend the most suitable MCCB solution within 24 working hours.

FAQ

Q1: What is the difference between L, M and H breaking grades?

A: L, M and H represent different rated short-circuit breaking capacities. L grade is for general distribution with lower fault current; M grade for standard industrial applications; H grade for heavy-duty industrial systems with high short-circuit current.

Q2: Does this MCCB have both overload and short-circuit protection?

A: Yes. It adopts thermal-magnetic trip mechanism: thermal bimetallic strip provides inverse-time overload protection, and electromagnetic coil provides instantaneous short-circuit protection.

Q3: What is the difference between 3P and 4P MCCB?

A: 3P MCCB switches three phase conductors only. 4P MCCB switches three phases plus neutral conductor together, used for 3-phase 4-wire systems where neutral disconnection is required for maintenance or fault isolation.

Q4: What standard does LMM1 MCCB comply with?

A: It complies with IEC 60947-2 international standard for low-voltage moulded case circuit breakers, and also meets GB/T 14048.2 national standard.

Q5: Can auxiliary contacts and shunt release be added?

A: Yes. Auxiliary contacts, alarm contacts, shunt release and under-voltage release accessories are available and can be installed according to project requirements.

Q6: Do you support OEM private label service for distributors?

A: Yes, we support custom logo and rating label printing on the product. A certain MOQ applies for OEM service.

Q7: Is this MCCB suitable for motor protection?

A: Yes. It can be used as motor feeder breaker for short-circuit and backup overload protection. For dedicated motor protection, it is recommended to cooperate with thermal overload relay.

Package Content

1 × LMM1 Series Moulded Case Circuit Breaker