Chint NM1-125S/3300-63A Molded Case Circuit Breaker

The Chint NM1-125S/3300-63A Molded Case Circuit Breaker (MCCB) is a high-performance power distribution protection device in the NM1 series of Chint Group (CHNT). It is suitable for power distribution systems with an AC frequency of 50Hz and a rated operating voltage up to 690V, and is mainly used for overload, short-circuit, and under-voltage protection. The following is a detailed analysis based on Chint’s official data and industry standards:

1. Core Parameters and Technical Characteristics
2. Basic Parameters

Rated Current (In): 63A, suitable for the load requirements of the circuit.

Frame Current (Inm): 125A, indicating the maximum current-carrying capacity of the circuit breaker.

Breaking Capacity:

Rated Ultimate Short-Circuit Breaking Capacity (Icu): 35kA (at 400V), meeting the safety requirements of medium and high-risk power distribution scenarios.

Rated Service Short-Circuit Breaking Capacity (Ics): 18kA, ensuring the circuit breaker can operate reliably after multiple faults.

Pole Number: 3 poles (the first “3” in 3300), applicable to three-phase four-wire or three-phase three-wire systems.

Tripping Characteristics:

Thermomagnetic Release (the second “3” in 3300), with both overload long-time delay (inverse time) and short-circuit instantaneous protection functions.

Inverse Time Operation Characteristics: The conventional non-tripping current is 1.05In (no tripping within 2 hours), the conventional tripping current is 1.30In (tripping within 2 hours), and the instantaneous operation is set to 10In±20%.

2. Electrical Performance

Rated Insulation Voltage (Ui): 800V, supporting the compatibility of high-voltage level systems.

Compliance with Standards: GB/T 14048.2 (equivalent to IEC 60947-2), and has obtained certifications such as CCC, KEMA, and CE, ensuring international versatility and reliability.

3. Structural Design

Installation Method: Supports vertical or horizontal installation, flexibly adapting to different cabinet layouts.

Wiring Method: Front-panel wiring (standard configuration); some upgraded models offer plug-in design (e.g., NM1-125S/3300 63A G).

Arc Flash Distance: ≤50mm, reducing the risk of damage to surrounding equipment caused by fault arcs.

1. Application Scenarios and Typical Configurations
2. Application Fields

Industrial Power Distribution: Power protection for power equipment such as machine tools and production lines.

Commercial Buildings: Control of distribution boxes and branch circuits in office buildings and shopping malls.

Residential and Small-Scale Infrastructure: Overload protection for indoor main incoming lines or high-power electrical appliances (e.g., air conditioners, electric water heaters).

2. Accessory Expansion

Auxiliary Functions: Can be equipped with a shunt release (for remote circuit breaking), an under-voltage release (for automatic disconnection when voltage is abnormal), or an alarm contact (for fault status signal output) to meet the needs of intelligent control.

Installation Compatibility: Accessory modules are universal with other models in the NM1 series, facilitating later function upgrades.

III. Usage and Maintenance Recommendations

1. Installation Specifications

Environmental Requirements: Ambient air temperature ranges from -5℃ to +40℃, altitude ≤2000m, and strong magnetic field interference should be avoided.

Wiring Requirements: Tighten terminal bolts to the specified torque (refer to the manual) to ensure reliable contact and prevent overheating.

2. Operation and Maintenance Key Points

Regular Inspection: Clean the dust on the housing every six months, check the wear of contacts, and replace them if necessary.

,Fault Troubleshooting: If frequent tripping occurs, it is necessary to check whether the load exceeds the limit, whether the line is short-circuited, or whether the setting value of the release is reasonable.

3. Replacement and Upgrade

New Model Replacement: Since 2021, Chint has launched upgraded platform-type products (models with suffix “G”), such as NM1-125S/3300 63A G. The breaking capacity is increased to 50kA, and the installation dimensions are compatible with the old models, enabling seamless replacement.

Local Procurement: Contact Chint’s authorized distributor via WhatsApp: 0086-13811255435 to obtain spot goods and technical support.

1. Key Considerations for Selection
2. Matching of Breaking Capacity: Select the corresponding breaking level (e.g., Type S: 35kA, Type H: 50kA) according to the short-circuit current level to avoid equipment damage due to insufficient selection.
3. Adaptation of Tripping Curve: For power distribution scenarios, Type C (5-10 times In instantaneous tripping) is preferred; for motor protection, Type D (10-14 times In) is required.
4. Certification Compliance: For domestic projects, CCC certification must be confirmed; for export projects, attention should be paid to the standards of the target market (e.g., CE, NOM).