What Is The Difference Between VFD And Soft Starter?
When choosing an ideal motor control solution for industrial use, often two prominent devices come up: the variable frequency drive (VFD) and soft starter. Both variable frequency drives and soft starters are designed to enhance the operation of a motor, but they fulfill different purposes. In this article, we will compare and contrast VFDs & soft starters by outlining their applications; giving both their advantages as well as limitations; ultimately it will provide direction on how to choose what will be best fit your specific needs.
VFD vs soft starter
The following table will compare VFD with soft starter based on key differences:
|
Aspect |
VFD |
Soft starter |
|
Primary functionality |
Change motor speed and torque via frequency changes and voltage changes. |
Limit inrush current and reduce mechanical stress only on startup. |
|
Speed control |
Variable speed control throughout the operation of the motor. |
Fixed speed operation after startup – no speed control. |
|
Energy savings |
Very efficient for applications with variable loads. |
Limited energy savings due to fixed speed operation. |
|
Cost |
Higher initial cost and more complex installation than soft starter. |
Lower initial cost and less complicated to install than VFD. |
|
Application |
Most suitable for variable speed applications such as conveyors, pumps, and HVAC. |
Usually used for fixed-speed applications such as compressors and fans. |
When should i use a VFD or soft starter?
Your application will help determine whether to use a VFD or soft starter. If you need to provide varying speed operation, precise motor control, or are frequently starting and stopping, a variable frequency drive is the best option for your application. Conversely, if the goal is simply to reduce mechanical stress on the motor during startup in a fixed speed application, then a soft starter is a better option and is often the most economical.
Energy savings are also very important! A VFD can drastically cut the amount of energy required to run a motor when the load requires variable speeds, but if the motor will only ever be run at a fixed speed, there isn't much reason to install that VFD because of its cost and complexity.
