When should you use a soft starter instead of a VSD?

Situation	Why a Soft Starter is the Better Choice
Motor runs at full speed most of the time	If speed variation is not required, a VSD is often unnecessary. A soft starter provides smooth starting without added complexity.
Lower-cost solution required	Soft starters are typically more cost-effective than VSDs especially above 7.5kW, with lower upfront cost and simpler installation.
Need to reduce inrush current and mechanical stress	Soft starters limit starting current and torque, helping protect motors and connected equipment.
Simplicity and reliability are priorities	With fewer parameters and straightforward setup, soft starters allow faster commissioning and easier operation.
Harmonic distortion needs to be minimised	Soft starters introduce minimal harmonics compared to VSDs, helping maintain power quality.
Panel space and heat are limited	Soft starters are generally more compact and generate less heat, particularly with built-in bypass.
Retrofitting or replacing DOL or star-delta starters	They provide an easy upgrade path with minimal system changes while improving motor protection.
EMC compliance is a concern	Soft starters typically avoid the need for additional filters or shielded cabling often required with VSDs.

 

In summary: If variable speed control is not required, a soft starter offers a simpler, more efficient, and cost-effective solution for most motor starting applications.

We stock a wide range of Soft starter Products available for next day delivery

 

Created by Inverterdrive Supermarket. Last reviewed May 2026