NM1 250H 50kA 3Pole MCCB

A. Product Overview

CHINT NM1 250H is a moulded case circuit breaker (MCCB) designed for reliable protection of three-phase power circuits against overload and short-circuit faults. The NM1 series is built in accordance with IEC/EN 60947-2 and is suitable for AC systems up to 690 V.
The “250H” designation refers to the 250 A frame size with H-type higher breaking capacity, rated up to 50 kA at 415 V, making it suitable for installations with high prospective fault currents. This MCCB is commonly applied as an incomer or outgoing feeder in industrial distribution boards where compact size, robust protection, and standardised accessories are required.

B. Working Principle

The NM1 MCCB uses a thermo-magnetic release system. The thermal element provides inverse-time tripping during overload conditions, protecting cables and downstream equipment from overheating. The magnetic element operates instantaneously during short-circuit events to rapidly isolate the fault and limit damage.
The breaker also functions as a manual isolator, allowing safe disconnection of circuits during maintenance. Optional internal accessories such as shunt release, under-voltage release, auxiliary contacts, and alarm contacts enable remote tripping, interlocking, and status monitoring in automated panels.

C. Key Applications

• Oil & Gas: Utility distribution boards, MCC feeders in non-hazardous areas

• Chemical & Process: Power feeders to MCCs, heater panels, and process auxiliaries

• Power & Utilities: Station service and auxiliary LV distribution

• Pharma: Clean utility and facility power distribution panels

• Food & Beverage: Process utility feeders and refrigeration distribution

• Water & Wastewater: Pump house and treatment plant power feeders

• HVAC & Utilities: Chiller plant and large AHU power distribution

D. Why Industries Use This Product

Industrial electrical systems require dependable fault isolation to prevent fire hazards, equipment damage, and extended downtime. The NM1 250H provides high short-circuit breaking capacity in a compact MCCB format, making it suitable for plants with higher fault levels without oversizing to larger ACBs.
Incorrect selection or installation—such as insufficient breaking capacity, poor termination, or lack of coordination with upstream/downstream devices—can lead to failure to clear faults, contact damage, or unsafe operating conditions. The NM1 series supports standardized installation practices, defined tightening torque, and accessory integration to reduce such risks.

E. Suitable Buyers

• OEMs: MCC and power panel manufacturers using standardized IEC MCCBs

• EPC Contractors: Industrial electrical packages and LV distribution systems

• Maintenance & Utilities Teams: Commonly used for replacement in NM1-based panels

• Plant Engineering & Procurement: Preferred for retrofit projects requiring high breaking capacity and IEC 60947-2 compliance

Quick Answers

What is CHINT NM1 250H 50kA 3P MCCB?
It is a three-pole moulded case circuit breaker rated on a 250 A frame with 50 kA short-circuit breaking capacity, used for industrial LV power protection.

Where is NM1 250H MCCB used?
Used as incomers or outgoing feeders in industrial distribution boards, MCCs, and utility panels with high fault levels.

Why is NM1 250H required in industry?
It provides reliable overload and short-circuit protection where standard MCBs or lower-capacity MCCBs are insufficient, reducing fire and equipment damage risk.

Who typically uses NM1 250H MCCB?
Panel builders, EPC contractors, plant maintenance teams, and industrial procurement engineers.

FAQ Section

1) Is NM1 250H suitable for high fault-level industrial systems?
Yes. The H-type NM1-250 is rated with higher breaking capacity (up to 50 kA at 415 V), making it suitable for installations with higher prospective short-circuit currents, provided system fault calculations are within rated limits.

2) Does NM1 250H provide motor protection?
The standard NM1 250H is primarily for power distribution. Motor protection requires appropriate release selection and coordination with thermal overload relays, depending on application and trip characteristics.

3) Can accessories be added to NM1 250H MCCB?
Yes. The NM1 series supports shunt release, under-voltage release, auxiliary contacts, alarm contacts, motor-driven operation, and rotary handles, enabling integration with automation and safety systems.

4) Can this MCCB be used as a main incomer?
It is commonly used as a main or sub-incomer in LV panels where the rated current and breaking capacity match system requirements and coordination studies.

5) What installation practices are critical for reliability?
Use correct copper conductor sizes, apply specified tightening torque, ensure adequate ventilation, and verify coordination with upstream and downstream protective devices. Poor termination and incorrect coordination are common causes of overheating and nuisance trips.