VFDs and soft starters both reduce the stress of starting an AC motor, but they solve different application problems. A VFD controls speed and frequency during operation. A soft starter primarily controls voltage during starting and stopping while the motor normally runs at line frequency.
When a VFD fits
Choose a VFD when the process needs adjustable speed, controlled torque, frequent speed changes, network feedback, or energy control in a variable-torque application. Conveyors, pumps, fans, and mixers commonly use drives for these reasons.
When a soft starter fits
A soft starter may suit a motor that normally runs at full speed but needs reduced starting current or smoother mechanical acceleration. It does not provide the same continuous speed control as a VFD.
Decision factors
| Requirement | VFD | Soft starter |
|---|---|---|
| Adjustable running speed | Yes | Usually no |
| Controlled acceleration | Yes | Yes |
| Energy application | Can reduce speed demand | Limited to starting behavior |
| Application complexity | Higher configuration | Often simpler |
Choose from the process
Review motor duty, load, starting torque, stopping needs, bypass requirements, harmonics, space, maintenance, and PLC integration. TechControl provides VFD programming and controls integration for motor applications.
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