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

The Chint Motor Protection Switch NS225/610A is a type of AC motor starter in the NS2 series, mainly used for protecting threephase squirrelcage 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: 610A

Breaking Capacity: 8KA

Operation Type: Manual operation

Overall Dimension: 36×86mm

Installation Method: Guiderail type

Functional Features

Protection Function: It has overload protection and shortcircuit 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 phasefailure 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 highstrength flameretardant 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, phasefailure and shortcircuit protection of threephase squirrelcage 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 NS225/610A and Molded Case Circuit Breaker NM163/3300

The advantages and disadvantages of the Chint Motor Protection Switch NS225/610A and the Molded Case Circuit Breaker NM163/3300 should be judged according to specific application scenarios. The following are the core differences between the two and selection suggestions:

1. Comparison of Core Functions
2. NS225/610A (Specialized for Motor Protection)

Protection Function:

It integrates overload, phasefailure and shortcircuit 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 thermalmagnetic 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 shortcircuit current in motor circuits, it has a breaking capacity of 8kA, which is suitable for most industrial motor scenarios.

2. NM163/3300 (GeneralPurpose for Power Distribution Protection)

Protection Function:

It has basic overload and shortcircuit 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 57 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 NM163S) to 50kA (for NM163H), which is suitable for power distribution systems with high shortcircuit current (such as main distribution cabinets).

1. Analysis of Application Scenarios

Scenarios for Recommending NS225/610A

1. Motor Control and Protection:

If it is necessary to directly control threephase induction motors (such as water pumps and fans), the phasefailure protection and accurate overload adjustment (610A) 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. CostSensitive 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 70270 RMB per unit), it saves the cost of thermal relays, resulting in a lower overall cost.

Scenarios for Recommending NM163/3300

1. Main Protection of Power Distribution System:

If it is necessary to protect distribution cabinets, branch lines or nonmotor loads (such as lighting and heating equipment), the high breaking capacity (2550kA) 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 shortcircuit 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 LongTerm Reliability:

The NM1 adopts a thermalmagnetic release, which has strong antiinterference ability and is suitable for power distribution systems that operate for a long time.

III. Comparison of Key Parameters

1. Suggestions for Selection Decision
2. Clarify Load Type:

If it is a motor load, prioritize the NS2, as its phasefailure 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 ShortCircuit Current:

If the system shortcircuit current exceeds 8kA (such as near the main distribution cabinet), the NM163H (with a breaking capacity of 50kA) is required.

If the shortcircuit 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 longterm operation stability, making it suitable for industrial scenarios with strict reliability requirements.

1. Summary

Choose NS225/610A: When specialized motor protection, simplified circuit design or cost sensitivity is required.

Choose NM163/3300: 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 NS225/610A to protect the motor from damage caused by overload and phase failure.

For the distribution box in an office building: Use the NM163/3300 as the main switch, and match it with a shunt release to realize fire linkage poweroff.