Think about when you first get on a bicycle and start riding. Even on a flat stretch of road, you really have to push down on the pedals to start moving. You use a lot more muscle power to get going than to keep going – imagine how much energy you’d expend if you had to keep pedaling with the same force with which you started out?

It all boils down to simple mechanical principles. Most things need more power to start than they do to just run. The problem is, just like that initial pedaling is tough on your legs, the initial starting up of an AC electrical motor is tough on the motor and shaft. The torque and inrush current during a traditional start up are between seven and 10 times higher than running torque, which can cause mechanical and electrodynamic stress. This ultimately reduces the lifespan of the entire system.

A soft starter reduces this stress by continuously controlling the voltage supply of the motor during start up, adjusting it to the machine’s load behaviour and ensuring a smooth acceleration.

Soft starters are fully adjustable according to the specific requirements of the application. Conveyor belt systems, for example, can be smoothly started to avoid jerk and stress on drive parts. In pump applications, pressure surges can be avoided. Wherever they’re installed, soft starters limit the inrush current, which reduces transient voltage drops that could have a knock on effect on other loads.