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:

I. Core Parameters and Technical Characteristics

1. 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.

 II. Application Scenarios and Typical Configurations

1. 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.

 IV. Key Considerations for Selection

1. **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.

2. **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.

3. **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).