CHINT NXM250S-3300/180A molded case circuit breaker

The CHINT NXM250S-3300/180A molded case circuit breaker (MCCB) is a protective device specially designed for low-voltage power distribution systems, suitable for industrial, commercial, and residential applications. The following is a detailed analysis of its technical parameters, application scenarios, selection points, and maintenance suggestions:

1. Core Technical ParametersChint NB2LE C20 circuit breaker
2. Electrical Performance

Rated Current: 180A, suitable for medium to high-load circuits (e.g., motors, lighting distribution boxes).

Breaking Capacity:

Class S: Icu (ultimate breaking capacity) = 50kA, Ics (service breaking capacity) = 36kA (72% of Icu), applicable to scenarios where the short-circuit current ≤ 50kA.

Short-time withstand current (Icw): 30kA (1 second), ensuring stable contact closure during faults.

Pole Number: 3P (three-phase), supporting grounding systems such as TN-C-S.

Trip Type: Thermomagnetic (the second “3” in 3300 represents thermomagnetic tripping), providing overload long-time delay (inverse time) and short-circuit instantaneous protection.

Rated Voltage: AC 400V (up to 690V supported, but the 250A frame is not applicable at 690V).

2. Mechanical Characteristics

Installation Method: Fixed type, front-wiring design, compatible with standard 35mm rails.

Operation Mode: Manual closing, supporting remote shunt tripping (accessories need to be selected separately).

Dimensions: Approximately 105mm (W) × 188mm (H) × 85mm (D), compact size to save distribution cabinet space.

3. Environmental Adaptability

Operating Temperature: -5°C to +70°C, adaptable to high-temperature environments (e.g., unairconditioned power distribution rooms).

Altitude: ≤2000m, pollution degree 3, suitable for industrial environments.

1. Application Scenarios
2. Typical Applications

Power Distribution System: As a branch circuit switch to protect lines from overload and short-circuit faults (e.g., floor distribution boxes in commercial complexes).

Motor Control: Provides direct starting protection for motors below 150kW (needs to be used with contactors).

Renewable Energy: Protection for the output side of photovoltaic inverters, supporting bidirectional current (reverse power feeding capability needs to be confirmed).

2. Industry Adaptation

Industry: Power distribution for factory production lines, pump houses, and other power equipment.

Construction: Control of lighting and air conditioning systems in intelligent buildings.

Infrastructure: Small data centers, hospital emergency power systems.

III. Technical Features and Advantages

1. Intelligent Protection Functions

Overload Long-time Delay: Inverse time characteristics, allowing adjustment of the tripping curve according to load characteristics (e.g., motors require extended tripping time).

Short-circuit Instantaneous Protection: Quickly breaks short-circuit current with a response time <10ms.

Undervoltage Protection: Shunt undervoltage release can be selected (needs to be ordered separately), automatically tripping when the voltage is below 70% of the rated value.

2. High-reliability Design

Arc-guided Contacts: Reduces arc energy and extends contact life to 10,000 electrical operations.

Vibration-resistant Structure: Passed IEC 60068-2-6 vibration testing, suitable for industrial scenarios with frequent start-stop operations.

Flame-retardant Housing: Made of PA66+GF30 material, heat-resistant up to 125°C, compliant with UL94 V-0 standards.

3. Flexible Expandability

Abundant Accessories: Supports auxiliary contacts (AX/AL-M1), alarm contacts (AX/AL-M3), shunt trip coils, etc., enabling remote monitoring and fault alarm.

Phase Spacers: Arc-shaped arc-dividing plates can be selected to enhance interphase insulation and reduce short-circuit arc risks.

1. Selection and Installation Suggestions
2. Selection Points

Matching Breaking Capacity: Choose Class S (50kA) or Class H (70kA) based on the system short-circuit current. For example, Class S is usually sufficient when the transformer capacity ≤1600kVA.

Trip Unit Type:

Thermomagnetic (3300): Suitable for mixed loads (e.g., motors and lighting combined).

Electromagnetic (3200): Short-circuit protection only, suitable for pure resistive loads.

Accessory Selection:

– Remote control: Shunt trip coil (MX) + auxiliary contact (AX).

– Leakage protection: Need to select the NXMLE series (e.g., NXMLE-250S/3300-180A).

2. Installation Notes

Wiring Specifications: Use 240mm² copper cables (need to crimp OT terminals), tighten with a torque of 8N·m to avoid excessive contact resistance.

Environmental Conditions: The installation location should be well-ventilated to prevent dust accumulation (e.g., regular cleaning is required in textile factories).

Grounding Requirements: The metal housing must be reliably grounded with a yellow-green two-color wire, and the grounding resistance ≤4Ω.

1. Maintenance and Fault Handling
2. Routine Maintenance

Cleaning and Inspection: Use dry compressed air to remove internal dust quarterly, and check contact wear (replace if wear exceeds 1mm).

Function Testing: Use a testing box annually to verify tripping characteristics, ensuring that overload protection does not trip within 2 hours at 1.13 times the rated current and trips within 1 hour at 1.45 times.

2. Common Faults and Solutions

Inability to Close: Check if the energy storage spring is loose or if the trip unit is in the “re-tripping” position (needs manual reset).

False Tripping: View fault records through the control unit. If it is an instantaneous overcurrent, adjust the short-circuit protection threshold (e.g., increase from 10In to 12In).

Contact Overheating: Check if wiring terminals are loose or if the load has long-term exceeded the rated current (needs to be derated).

3. Warranty Policy

– The product comes with a 24-month warranty, and non-human damage can be replaced for free. It is recommended to purchase through CHINT authorized dealers to ensure after-sales service.

1. Certification and Compliance

Domestic Certification: Passed CCC certification (certificate number 2020980307002101), compliant with GB14048.2 standards.

International Standards: Compliant with IEC 60947-2, but CE certification is not explicitly marked; separate confirmation is required for exports.

VII. Comparison and Alternative Solutions

1. Comparison with Other NXM Series Models

NXM250H/3300: Breaking capacity increased to 70kA, suitable for systems with higher short-circuit currents (e.g., parallel transformers).

NXM250S/3300 vs NM1-250S: The NXM series is a new-generation product with a smaller size and higher breaking capacity (NM1-250S has a breaking capacity of 50kA but a larger size).

2. Competitor References

Schneider EasyPact NSX250N: Breaking capacity 50kA, supporting electronic trip units, but 30% higher in price.

Delixi CDB6LE-250: 15% lower in price, but breaking capacity is only 40kA, suitable for cost-sensitive civil projects.

VIII. Procurement and Technical Support

Channels: Purchase through CHINT’s official website or contact WhatsApp: 0086-13811255435, and verify the product serial number and CCC mark.

Summary: CHINT NXM250S-3300/180A has become an ideal choice for medium and low-voltage power distribution with its high cost-effectiveness, reliable protection performance, and flexible expandability. When selecting, focus on matching the breaking capacity and accessory requirements, and conduct regular maintenance after installation to ensure long-term stable operation.

Comparison Between CHINT NXM250S-3300/180A and Schneider MT16N1

The CHINT NXM250S-3300/180A molded case circuit breaker (MCCB) and Schneider MT16N1 air circuit breaker (ACB) differ significantly in technical positioning, functional design, and application scenarios. The following is a comparative analysis of core dimensions:

1. Product Positioning and Basic Types

NXM250S: Belongs to MCCB, positioned as a mid-range power distribution protection device, suitable for overload and short-circuit protection of branch circuits, with a rated current covering 180A (250A frame).

MT16N1: Belongs to ACB, positioned as a high-end power distribution core device, mainly used for main inlets or large-capacity circuits, with a rated current up to 1600A, supporting bidirectional current and complex system protection.

1. Comparison of Core Technical Parameters

III. Differences in Functions and Expandability

1. Depth of Protection Functions

NXM250S: Only provides two-stage thermomagnetic protection (overload long-time delay + short-circuit instantaneous), without selective protection capability, unable to distinguish fault levels.

MT16N1: Achieves four-stage protection (overload long-time delay, short-circuit short-time delay, instantaneous, ground fault) through the MIC control unit, supporting flexible adjustment of protection parameters to realize selective protection and narrow the power outage range.

2. Intelligence and Communication Capability

NXM250S: No built-in communication function, requiring a shunt trip coil to achieve remote opening, but cannot access energy management systems (EMS).

MT16N1: Supports communication-type control units such as MIC 6.0D, integrating Modbus, Profibus protocols, enabling real-time monitoring of power quality, fault recording, and seamless docking with smart grids.

3. Accessory Ecosystem

NXM250S: Accessories focus on basic control (shunt trip coils, auxiliary contacts), lacking advanced expansion functions.

MT16N1: Provides rich accessories, including phase spacers, door interlocks, electric operating mechanisms, communication modules, etc., supporting reverse power feeding and distributed energy access.

1. Application Scenarios and Adaptability

NXM250S:

Typical Scenarios: Commercial building floor distribution boxes, small industrial motor control (≤150kW), residential power distribution systems.

Limitations: Requires manual reset after tripping, no selective protection, unsuitable for scenarios with high requirements for power supply continuity.

MT16N1:

Typical Scenarios: Data center main inlets, hospital emergency power systems, factory power distribution main switches, photovoltaic inverter outlet protection.

Advantages: Drawer-type structure supports quick replacement, and the intelligent control unit can achieve precise fault positioning, ensuring continuous power supply for critical loads.

1. Reliability and Environmental Adaptability
2. Structural Design

NXM250S: Molded case packaging, compact size (100×40×3mm, 1kg), but internal contacts and arc extinguishers are small, with higher temperature rise under long-term high loads.

MT16N1: Metal frame + modular design, contact cross-sectional area more than 5 times that of NXM250S, better heat dissipation performance, suitable for long-term full-load operation.

2. Environmental Tolerance

NXM250S: Adaptable to -5°C to +70°C, altitude ≤2000m, but weak vibration resistance, unsuitable for industrial environments with frequent start-stop operations.

MT16N1: Passed IEC 60068-2-6 vibration testing, wider operating temperature range (-5°C to +70°C), anti-condensation design applicable to high-humidity environments (e.g., underground power distribution rooms).

1. Certification and Compliance

NXM250S: Passed domestic CCC certification, and some models (such as the NXMLE series) comply with CE and CB standards, but international market adaptability is limited.

MT16N1: Complies with international standards such as IEC 60947-2, UL, and ship classification societies, supports global project deployment, and has passed ISO 50001 energy efficiency certification, suitable for green energy projects.

VII. Cost and Maintenance

Procurement Cost: The price of NXM250S is about 1/3 to 1/2 of MT16N1, suitable for budget-sensitive projects.

Maintenance Cost:

NXM250S: Maintenance-free design, but overall replacement is required after contact wear, with lower single maintenance costs.

MT16N1: Modular design supports component replacement (such as control units, contact groups), but maintenance complexity is higher, requiring professional technicians.

Summary: How to Choose?

Scenarios Prioritizing NXM250S:

Limited budget, simple protection requirements (e.g., residential, small commercial), need for quick installation, and no intelligent monitoring requirements.

Scenarios Prioritizing MT16N1:

Main inlets or large-capacity circuits, requiring selective protection and intelligent communication (e.g., data centers, hospitals), long-term high-load operation, or harsh industrial environments.

The essential difference between the two lies in functional positioning: NXM250S is an economical and practical “branch guardian,” while MT16N1 is a “power distribution hub” ensuring system stability. Users should make comprehensive decisions based on system scale, protection complexity, and long-term operation and maintenance costs.