Chint NXM-250S-2300/250A Molded Case Circuit Breaker

   The Chint NXM-250S-2300/250A molded case circuit breaker is a high-performance low-voltage power distribution protection device, suitable for scenarios such as industrial, commercial, and photovoltaic systems. The following is a detailed analysis based on the search resources:

I. Core Parameters and Performance  YouTube：https://youtube.com/shorts/ekTnEjdF9Rw 

1. **Model Analysis**

   - **NXM Series**: It belongs to the Chint Kunlun series, positioned in the mid-to-high-end market. It supports thermal-magnetic trip units (TM) or electronic trip units (EM), and is suitable for complex power distribution systems.

   - **250S**: The frame current is 250A. The breaking capacity code "S" represents the standard breaking capacity (According to supplier information, it is 36kA, while the Chint official website shows that "S" corresponds to 35kA. It is necessary to confirm with the official source).

   - **2300**:

     - **The first digit "2"**: The number of poles is 2P (disconnecting the phase wire and the neutral wire simultaneously).

     - **The second digit "3"**: The type of trip unit is thermal-magnetic (TM), which supports long-time delay for overload and instantaneous protection for short circuits.

     - **The last two digits "00"**: The accessory configuration is without auxiliary contacts or shunt trip units (Some models may come with basic accessories, subject to specific orders).

   - **250A**: The rated current is 250A, and it supports the adjustment of the trip unit current (such as 160A, 180A, etc.).

2. **Key Parameters**

   - **Breaking Capacity**:

     - **Rated Ultimate Short-Circuit Breaking Capacity (Icu)**: 35kA (official website data) or 36kA (supplier data), applicable to an AC 400V system.

     - **Rated Service Short-Circuit Breaking Capacity (Ics)**: 35kA (Ics = Icu), which can break the short-circuit current multiple times.

   - **Tripping Characteristics**:

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

     - **Type D Curve**: Instantaneous tripping at 10-20 times the rated current, suitable for impact loads such as motors (It is necessary to confirm the configuration of the specific model).

   - **Voltage and Number of Poles**:

     - **Rated Insulation Voltage**: 690V, supporting AC 230V/400V systems.

     - **Number of Poles**: 2P (single-phase), which can be extended to 3P or 4P (It is necessary to adjust the model suffix).

3. **Certifications and Standards**

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

   - **International Certifications**: CE, KEMA, and CB certifications, applicable to export projects.

   - **Special Certification**: Some models support the DC 1500V photovoltaic system (It is necessary to confirm the specific configuration).

II. Application Scenarios

1. **Industrial and Commercial Power Distribution**

   - Motor control (such as water pumps, fans), and protection for the output of frequency converters.

   - Example: The 250A model can protect motors below 200kW, and the breaking capacity of 36kA meets the short-circuit requirements of most industrial applications.

2. **Photovoltaic Systems**

   - Short-circuit protection for the output of inverters or combiner boxes, supporting the mode of "self-generation for self-use and surplus power fed into the grid".

   - It needs to be used with DC accessories (such as DC disconnect modules), and some models support DC 1500V.

3. **Special Environments**

   - Environments with dust or vibration, such as coal mines and railways, require the use of dust-proof accessories.

   - Altitude ≤ 2000 meters, ambient temperature from -5°C to +40°C, humidity ≤ 90%.

 III. Installation and Accessories

1. **Installation Methods**

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

   - **Front-of-Panel Wiring**: Suitable for internal connection in distribution boxes, and the cross-sectional area of the wire ≤ 70mm².

   - **Electric Operating Mechanism**: Optional (such as NXMA-250S) to achieve remote control (Needs to be purchased additionally).

2. **Accessory Compatibility**

   - **Auxiliary Contacts**: Indicate the status of the circuit breaker (closed/open). The model suffix can be extended to "3300" (with auxiliary contacts).

   - **Shunt Trip Units**: Support remote tripping (such as linkage with fire alarms). The model suffix can be extended to "3310".

   - **Undervoltage Trip Units**: Automatically trip when the voltage is lower than the set value. The model suffix can be extended to "3320".

   - **Leakage Protection Modules**: Some models integrate leakage protection (such as the NXMLE series), with a leakage operating current of 30mA (for household use) or 300mA (for industrial use).

 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).

     - Example: If the load current is 200A, select In = 250A to ensure safe long-term operation.

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

     - Example: If the short-circuit current is 30kA, select the NXM-250S with Icu = 36kA.

   - **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, derate it to 80%).

2. **Maintenance Suggestions**

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

   - **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**

   - **Price Range**: The price of the 250A/2300 model is approximately between 300 yuan and 600 yuan, specifically depending on the accessory configuration.

   - **Suppliers**: Authorized Chint dealers (Hebei china Electric).

2. **Alternative Models**

   - **Schneider NSX Series**: For example, the NSX100N has a breaking capacity of 50kA and supports intelligent trip units.

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

Conclusion

With its high cost-effectiveness and flexible configuration, the Chint NXM-250S-2300/250A molded case circuit breaker is suitable for industrial, commercial, and photovoltaic systems. When selecting the model, attention should be paid to the breaking capacity, the number of poles, and the accessory compatibility. If necessary, refer to the official documents or contact technical support. 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 conduct derating design in combination with the load characteristics and environmental conditions to ensure the safe and reliable operation of the system.