Chint 2P Molded Case Circuit Breaker

   The Chint 2P molded case circuit breaker is a commonly used protection device in low-voltage power distribution systems, suitable for the protection against overload, short circuit, and leakage in single-phase circuits. The following is a detailed analysis based on the search resources:

I. Core Parameters and Performance

1. **Models and Series**

The Chint 2P molded case circuit breakers mainly include the following series:

- **NXB Series**: An economical type with a rated current of 16A - 63A and a breaking capacity of 6kA (Type C curve), suitable for residential and small commercial places.

- **NXM Series**: A high-performance type with a frame current of 63A - 1600A and a breaking capacity of 25kA - 85kA. It supports thermal-magnetic trip units (TM) or electronic trip units (EM), and is suitable for industrial and medium to large commercial scenarios.

- **NM1 Series**: An upgraded type with a breaking capacity of 45kA - 85kA, supporting undervoltage protection, and suitable for motor control and power distribution lines.

2. **Key Parameters**

- **Rated Current (In)**: 16A - 250A (There are significant differences among different series).

- **Breaking Capacity**:

    - NXB Series: 6kA (Type C) or 10kA (Type D).

    - NXM Series: 25kA - 85kA (For example, the breaking capacity of NXM-63S is 25kA, and the breaking capacity of NXM-1000SP is 50kA).

- **Tripping Characteristics**:

    - **Type C**: Instantaneous tripping at 5 - 10 times the rated current, suitable for lighting loads.

    - **Type D**: Instantaneous tripping at 10 - 20 times the rated current, suitable for impact loads such as motors.

- **Voltage and Number of Poles**:

    - Rated Insulation Voltage: 690V (NXM Series) or 500V (NXB Series).

    - Number of Poles: 2P (Disconnecting the phase wire and the neutral wire simultaneously).

3. **Leakage Protection Function**

- Some models integrate a leakage protection module (such as the NXBLE series). The leakage operating current is 30mA (for household use) or 300mA (for industrial use), which is suitable for ground fault protection.

II. Application Scenarios

1. **Residential and Small Commercial**

- Protection of single-phase loads such as the main switch of the distribution box, air conditioner circuits, and water heaters.

- Example: The NXB-63 2P C32 is used for the circuit of a 3-horsepower air conditioner, and the breaking capacity of 6kA meets the short-circuit requirements of households.

2. **Industrial and Photovoltaic Systems**

- Motor control and protection of the output of frequency converters.

- Short-circuit protection for the output of photovoltaic combiner boxes or inverters (For example, the NXM series supports the DC1500V system).

3. **Special Environments**

- In dusty or vibrating environments such as coal mines and railways, dust-proof accessories need to be used.

- Altitude ≤ 2000 meters, ambient temperature from -5°C to +40°C.

III. Installation and Accessories

1. **Installation Methods**

- **Rail Installation**: Supports the 35mm standard rail for quick fixing.

- **Front-of-Panel Wiring**: Suitable for internal connection in distribution boxes.

- **Electric Operating Mechanism**: Optional for some models (such as NXM-1000SP) to achieve remote control.

2. **Accessory Compatibility**

- **Auxiliary Contacts**: Indicate the status of the circuit breaker (closed/open).

- **Shunt Trip Units**: For remote tripping (such as linkage with fire alarms).

- **Undervoltage Trip Units**: Automatically trip when the voltage is lower than the set value.

- **Leakage Protection Module**: The NXBLE series integrates a zero-sequence current transformer to provide ground fault protection.

IV. Selection and Maintenance

1. **Selection Key Points**

- **Load Matching**: The trip unit current (In) ≥ the calculated load current (Ic), and ≤ the current-carrying capacity of the conductor (Iz).

- **Short-Circuit Capacity**: Select the breaking capacity (Icu/Ics) according to the expected short-circuit current at the installation site.

- **Environmental Conditions**: It needs to be derated for use in high-temperature or high-humidity environments (For example, when the ambient temperature is 40°C, the NXB series is derated to 80%).

2. **Maintenance Suggestions**

- **Regular Inspection**: Clean the contacts and check whether the trip unit operates normally.

- **Avoid Overload**: Long-term overload will accelerate the wear of the contacts and shorten the service life.

- **Fault Handling**: After the short-circuit trip, check the ablation condition of the contacts, and replace the circuit breaker if necessary.

V. Market Status and Alternative Solutions

1. **Price and Suppliers**

- **NXB Series**: The price of models with a current of 16A - 63A is about 10 yuan - 50 yuan, and the suppliers include JD.com, Alibaba, etc.

- **NXM Series**: The price of models with a current of 63A - 1600A is about 200 yuan - 8000 yuan, and they need to be purchased through authorized Chint dealers.

2. **Alternative Models**

- **Schneider NSX Series**: Higher breaking capacity (For example, the breaking capacity of NSX100N is 50kA), and it supports intelligent trip units.

- **ABB TMAX XT Series**: The electronic trip units support multi-stage protection, suitable for complex power distribution systems.

VI. Official Resources and Certifications

- **Operation Manual**: Obtained through the Chint official website or authorized dealers, and the content covers installation, wiring, and troubleshooting.

- **Certification Standards**:

    - **Domestic**: CCC certification, in line with GB/T 14048.2 (Low-voltage switchgear).

    - **International**: CE certification (NXM series), CB certification, applicable to export projects.Conclusion

With its high cost-effectiveness and flexible configuration, the Chint 2P molded case circuit breaker is widely used in residential, commercial, and industrial scenarios. When selecting the model, an appropriate series (such as the economical NXB series and the high-performance NXM series) should be selected according to the load type, short-circuit capacity, and environmental conditions, and attention should be paid to the accessory compatibility. If higher performance or intelligent functions are required, the Schneider NSX or ABB TMAX series can be considered. In practical applications, it is recommended to refer to the Chint official manual or contact technical support to ensure that the selection and installation comply with the standards.