Chint NM1LE-250S/4300S-160A 4-pole molded case residual current circuit breaker

Chint NM1LE-250S/4300S-160A is a 4-pole molded case residual current circuit breaker (RCB). It is suitable for power distribution systems with AC 50Hz and rated voltage up to 400V, and is mainly used for overload, short-circuit and residual current protection. The following is a detailed analysis of its key parameters and functions:

 I. Core Parameters and Model Meaning

1. Model Structure

- **NM1LE**: Series code, where "NM" stands for molded case circuit breaker, and "LE" indicates the function of residual current protection.

- **250S**: Frame current is 250A; "S" means the breaking capacity is 30kA (in compliance with GB/T 14048.2 standard).

- **4300S**:

  - **4**: 4-pole design, which can disconnect three-phase live wires and neutral wire simultaneously.

  - **300**: The release type is thermal-magnetic (dual release), which has both overload long-time delay and short-circuit instantaneous protection functions.

  - **S**: May indicate the breaking capacity level (consistent with the "S" after the frame current).

- **160A**: Rated current is 160A, applicable to circuits where the load current does not exceed this value.

2. Residual Current Protection Characteristics

- **Rated residual operating current (IΔn)**: 100-200-300mA with three adjustable gears. The sensitivity can be selected according to actual needs (e.g., 300mA is suitable for fire protection, and 100mA is suitable for personal safety protection).

- **Residual breaking time**: ≤0.1 second (non-delayed type), which can quickly cut off the residual current circuit to ensure safety.

- **Residual non-operating current (IΔno)**: 50% of IΔn (i.e., 50-100-150mA), so as to avoid false tripping.

3. Breaking Capacity and Short-Circuit Protection

- **Rated ultimate short-circuit breaking capacity (Icu)**: 30kA, which can reliably break when the short-circuit current reaches 30kA, so as to protect lines and equipment.

- **Arc flash distance**: ≤50mm, which reduces the hazard of electric arc during short-circuit.

 II. Functions and Application Scenarios

1. Multiple Protection Functions

- **Overload protection**: The thermal release is used to monitor the current. When the load current exceeds the rated value, the circuit will be disconnected with a delay according to the inverse time characteristic.

- **Short-circuit protection**: The magnetic release is triggered instantly when short-circuit current occurs, and quickly cuts off the circuit to prevent equipment damage.

- **Residual current protection**: It monitors the residual current in real time. When the residual current reaches the set value, it trips immediately to prevent electric shock and electrical fire.

 2. Application Scope

- **Industrial power distribution**: Used as the main switch or branch switch of the distribution cabinet, it is suitable for scenarios such as motor control and equipment power supply.

- **Commercial and civil use**: Can be used in distribution boxes of office buildings and residences to protect the safety of end circuits, and is especially suitable for humid environments (such as kitchens and bathrooms).

- **Special environments**: Supports operation in a wide temperature range from -5℃ to +40℃, and can withstand environments with an altitude below 2000 meters and pollution degree 3.

III. Installation and Operation Characteristics

 1. Installation Methods

- **Fixed installation**: Fixed in the distribution cabinet through front-panel wiring, supporting vertical or horizontal installation.

- **Accessory expansion**: Accessories such as alarm contacts, shunt releases, and undervoltage releases can be added to realize remote control or fault early warning (e.g., the shunt release can open the circuit through an external signal).

2. Operation and Maintenance

- **Manual operation**: Direct switching on/off through the handle, with intuitive and safe operation.

- **Tool-free maintenance**: The modular design facilitates maintenance, and the standard phase isolation plates prevent phase-to-phase short circuits.

- **Service life parameters**: Mechanical life is 20,000 times, and electrical life is 8,000 times, which reduces the replacement frequency.

IV. Certification and Compliance

- **Standard certification**: Has passed certifications such as CCC, KEMA, and CE, complies with international standards including GB/T 14048.2 and IEC 60947-2, and features reliable quality.

- **Environmental adaptability**: IP20 protection rating, which is dust-proof and anti-electric shock, and adaptable to dusty or humid environments.

V. Precautions for Model Selection

1. **Load matching**: Ensure that the rated current of 160A matches the actual load current to avoid overload or underload operation.

2. **Residual current sensitivity**: Select the residual operating current according to the scenario (e.g., 30mA for direct contact protection, 300mA for fire protection).

3. **Accessory requirements**: If remote control or fault alarm is needed, configure corresponding accessories in advance (e.g., additional model selection is required for shunt releases).

4. **Price reference**: The market price is approximately 242-468 RMB per unit, and the specific price is subject to the quotation of distributors.

VI. Typical Application Example

In a three-phase four-wire industrial power distribution system, NM1LE-250S/4300S-160A can be used as a branch switch to protect a motor with a rated power of approximately 75kW. By setting the residual operating current to 300mA, it can effectively prevent residual current fires caused by motor insulation aging; at the same time, the thermal-magnetic release can cope with the instantaneous inrush current when the motor starts, ensuring the safe operation of the equipment.