When electric motors are started direct-on-line they often need a high starting current. This can produce voltage drops, mechanical shock and stress on the motor system.
A soft starter for motor is used to gradually increase the motor voltage at startup to provide a smooth acceleration process.
Soft starters are commonly used in pumps, fans, compressors, conveyors, crushers and other industrial applications where speed control is not required but soft starting is required.
However, the proper soft starter should be chosen according to motor power, voltage, starting frequency and load characteristics.
1. Check the Motor Nameplate
The first step to select a soft starter for motor is to check the motor information.
Buyers are to supply:
- Speed motor
- Voltage, rated
- Current rating
- Motor frequency
- Type of Motor
- Initial condition
Especially important is the rated current.
The soft starter rated current should be equal or higher than the motor rated current.
For heavy duty applications also the overload capacity and the starting time should be considered.
2. Check the Motor Load
Different loads require different soft starter performance.
Light loads such as fans and pumps usually have easier starting conditions.
However, heavy loads such as crushers, conveyors and large compressors may require higher starting torque and longer acceleration time.
Before selecting a soft starter for motor, buyers should check:
- Load type
- Starting torque requirement
- Starting time
- Number of starts per hour
- Operating environment
A correct selection can reduce mechanical stress and extend motor system life.
3. Choose the Suitable RENLE Soft Starter
After confirming the motor and load conditions, buyers can select the suitable soft starter.
For medium-voltage motor applications, the RENLE Medium Voltage Soft Starter can be considered.
RENLE medium-voltage soft starters are designed for industrial applications including pumps, fans, compressors, conveyors and other large motor systems.
They help reduce starting current, minimize mechanical impact and provide reliable motor starting performance.
For large industrial motors, medium-voltage soft starters can provide an effective solution where variable speed control is not required.
4. Prepare These Details Before Quotation
To receive a faster and more accurate soft starter for motor recommendation, buyers should prepare:
- Motor power
- Rated voltage
- Rated current
- Motor type
- Load type
- Starting torque requirement
- Starting frequency
- Acceleration time
- Installation environment
If the project requires bypass contactor, communication function, protection functions or special cabinet design, these requirements should also be confirmed before quotation.
5. Simple Selection Process
The selection process can be summarized as:
- Check the motor nameplate.
- Check the load characteristics.
- Confirm the starting requirements.
- Select the soft starter according to motor voltage and current.
- Choose the suitable RENLE soft starter model.
If you need a soft starter for motor, send RENLE your motor nameplate and application information.
Our engineers can help recommend a suitable soft starter model and configuration for your project.
FAQ: Soft Starter for Motor
Q:What is a soft starter for motor?
A: A soft starter for motor is a device that controls the voltage supplied to an electric motor during startup.
It gradually increases the motor voltage, reducing starting current and mechanical shock compared with direct-on-line starting.
Q: When should I use a soft starter instead of a VFD?
A: A soft starter is suitable when the main purpose is to achieve smooth motor starting and reduce starting impact.
A VFD is more suitable when the application requires continuous speed adjustment, energy saving through speed control or advanced process control.
Q: How do I select the right soft starter size?
A: The soft starter should be selected according to:
- Motor power
- Rated voltage
- Motor rated current
- Load type
- Starting torque requirement
- Starting frequency
The soft starter rated current should meet or exceed the motor rated current.
