Choosing The Correct Motor Control Device

Before selecting your motor control device, consider the following:

1.Determine key specifications of motor

Start with determining your motor basic rated voltages, power and full-load current. These specs normally found on the motor nameplate; will be critical in determining what kind of starting device is compatible.

2.Evaluate starting current requirements

For soft starter systems, determine the starting current range. For VFD systems, determine what rated currents are available for the ambient conditions you will be operating in.

3.Evaluate system functional requirements

If your system requires speed control, energy optimization or additional protection for the motor then VFD is likely to be more appropriate although it will be more costly. If you have a simple application with soft-start and soft-stop requirements and do not require speed control, then soft starter will be adequate.

4.Evaluate the application

The type of application you will be using the motor in will have a significant impact on your final selection. A VFD would generally be the preferred starting device for all applications where flexible operations such as material handling or variable speed pumps will be utilized. Conversely, for applications which will only be operated at constant speed, soft starter will work efficiently.

5.Consult manufacturer

Always consult the manufacturer of your soft starter or VFD on their sizing chart or models that have been designed for your specific application prior to making a final selection. Consulting an expert may help you find the best and most affordable fit for your system.

Soft starter vs VFD comparison

When it comes to selecting your control device, below is a comparison chart that highlights specific features associated with each device, including starting current, function, cost, and typical application.