Chint Motor Protection Switch NS2-25/6-10A

The Chint Motor Protection Switch **NS2-25/6-10A** is a type of AC motor starter in the NS2 series, mainly used for protecting three-phase squirrel-cage induction motors. The following is a detailed introduction:

Basic Parameters

- **Frame Current**: 25A

- **Rated Insulation Voltage**: 690V

- **Rated Working Voltage**: AC230/240V, 400/415V, 440V, 500V, 690V

- **Adjustable Current Range**: 6-10A

- **Breaking Capacity**: 8KA

- **Operation Type**: Manual operation

- **Overall Dimension**: 36×86mm

- **Installation Method**: Guide-rail type

Functional Features

- **Protection Function**: It has overload protection and short-circuit protection functions. When the current exceeds the set value, it can act within milliseconds to cut off the power supply, preventing equipment damage or fire hazards. It also has phase-failure protection function.

- **Reset Function**: After troubleshooting, it can be restarted by simply pressing the reset button, which is easy and convenient to operate.

- **Structural Features**: It adopts a shell made of high-strength flame-retardant material, which is resistant to high temperature and dust. With a modular structure, it is easy to install and can be easily embedded in distribution boxes or control cabinets.

Application Scope

It is suitable for circuits with AC voltage up to 690V and current up to 80A. It can be used for overload, phase-failure and short-circuit protection of three-phase squirrel-cage induction motors as well as infrequent starting control. It can also be used for distribution line protection, infrequent load switching and as an isolator.

 Comparison Between Chint Motor Protection Switch NS2-25/6-10A and Molded Case Circuit Breaker NM1-63/3300

The advantages and disadvantages of the Chint Motor Protection Switch **NS2-25/6-10A** and the Molded Case Circuit Breaker **NM1-63/3300** should be judged according to specific application scenarios. The following are the core differences between the two and selection suggestions:

 I. Comparison of Core Functions

1. NS2-25/6-10A (Specialized for Motor Protection)

- **Protection Function**:  

  It integrates **overload, phase-failure and short-circuit protection**, and supports **manual reset**, which is specially designed for motors. For example, when the motor current is abnormal due to excessive load or power phase loss, the NS2 can cut off the circuit within milliseconds and accurately respond to motor characteristics (such as starting current peak) through the thermal-magnetic release.

- **Structural Design**:  

  It is an integrated module that does not require additional accessories (such as thermal relays), saving installation space (with a dimension of 36×86mm) and directly adapting to the motor control circuit.

- **Breaking Capacity**:  

  Designed for the common short-circuit current in motor circuits, it has a breaking capacity of **8kA**, which is suitable for most industrial motor scenarios.

2. NM1-63/3300 (General-Purpose for Power Distribution Protection)

- **Protection Function**:  

  It has basic **overload and short-circuit protection** functions, but **additional thermal relays** are required to achieve motor overload protection. If it is directly used for motor control, it may trip incorrectly due to the starting current (usually 5-7 times the rated current), so it is necessary to adjust the tripping curve or add accessories.

- **Structural Design**:  

  As a molded case circuit breaker, it needs to be installed with a separate thermal relay (such as the NR2 series), resulting in a larger overall volume and possibly higher cost.

- **Breaking Capacity**:  

  The breaking capacity ranges from **25kA (for NM1-63S)** to **50kA (for NM1-63H)**, which is suitable for power distribution systems with high short-circuit current (such as main distribution cabinets).

II. Analysis of Application Scenarios

Scenarios for Recommending NS2-25/6-10A

1. **Motor Control and Protection**:  

   If it is necessary to directly control three-phase induction motors (such as water pumps and fans), the **phase-failure protection** and **accurate overload adjustment** (6-10A) of the NS2 can effectively prevent motor burnout. For example, when the motor is locked due to a stuck belt, the NS2 will trip quickly, while the NM1 may not respond in time if no thermal relay is configured.

2. **Simplified Circuit Design**:  

  The NS2 integrates circuit breaking, protection and isolation functions, and does not require additional components, making it suitable for control cabinets with limited space. For example, the NS2 can be directly installed in small automated equipment to reduce wiring complexity.

3. **Cost-Sensitive with Specialized Protection Requirements**:  

  The price of the NS2 is approximately **60 RMB per unit**. Although it is slightly higher than that of the NM1 (about 70-270 RMB per unit), it saves the cost of thermal relays, resulting in a lower overall cost.

Scenarios for Recommending NM1-63/3300

1. **Main Protection of Power Distribution System**:  

   If it is necessary to protect distribution cabinets, branch lines or non-motor loads (such as lighting and heating equipment), the **high breaking capacity** (25-50kA) and **long service life** of the NM1 are more advantageous. For example, using the NM1 as the main switch in the main distribution box can effectively deal with sudden short-circuit faults.

2. **Complex Load Combination**:  

   When the same circuit needs to protect both motors and other equipment (such as frequency converters and PLCs), the NM1 can achieve flexible control through **modular expansion** (such as adding shunt releases and auxiliary contacts).

3. **Requirements for Long-Term Reliability**:  

   The NM1 adopts a **thermal-magnetic release**, which has strong anti-interference ability and is suitable for power distribution systems that operate for a long time.

 III. Comparison of Key Parameters

IV. Suggestions for Selection Decision

1. **Clarify Load Type**:  

   - If it is a **motor load**, prioritize the **NS2**, as its phase-failure protection and accurate overload adjustment are irreplaceable by the NM1.  

   - If it is a **mixed load or pure power distribution system**, select the **NM1** and add thermal relays or other accessories as needed.

2. **Calculate Short-Circuit Current**:  

   - If the system short-circuit current exceeds **8kA** (such as near the main distribution cabinet), the **NM1-63H** (with a breaking capacity of 50kA) is required.  

   - If the short-circuit current is low (such as in branch lines), the 8kA breaking capacity of the NS2 is sufficient.

3. **Consider Expansion Requirements**:  

   - If remote control (such as shunt release) or signal feedback (such as auxiliary contacts) is needed in the future, the modular design of the NM1 is more flexible.

4. **Cost and Maintenance**:  

   - The NS2 has a low initial cost and simple maintenance (no additional accessories required), making it suitable for projects with limited budgets.  

   - The NM1 has high long-term operation stability, making it suitable for industrial scenarios with strict reliability requirements.

V. Summary

- **Choose NS2-25/6-10A**: When **specialized motor protection**, **simplified circuit design** or **cost sensitivity** is required.  

- **Choose NM1-63/3300**: When **high breaking capacity**, **main protection of power distribution system** or **expansion functions** are required.  

**Example Scenarios**:  

- For the water pump control circuit in a factory: Directly select the NS2-25/6-10A to protect the motor from damage caused by overload and phase failure.  

- For the distribution box in an office building: Use the NM1-63/3300 as the main switch, and match it with a shunt release to realize fire linkage power-off.