VSD’s and Soft Starters

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.

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Variable Speed Drives

A variable speed drive (VSD) picks up where the soft starter leaves off, helping to keep the motor running at a consistent speed for both optimum operational efficiency and maximum electrical economy. They do this by controlling the power that is fed into the machine.

Industry estimates show that VSDs in operation around the world save in excess of 115 million megawatt hours of electricity every single year. That’s about as much power as is generated by 14 nuclear power stations! Of course, reduced electricity consumption not only saves money, but also helps save the environment – VSDs reduce carbon dioxide emissions by almost 100 million tonnes every year.

The significant energy savings realised by variable speed drives mean the cost of the drive and its installation is often recouped in a matter of months.

VSDs come in many different sizes – from as small as a juice carton to as big as a clothing cupboard – depending on the size of the motor they’re responsible for regulating. JB Switchgear has a comprehensive range of soft starters and VSDs designed to customer requirements and manufactured for indoor or outdoor applications. Chat to us today about how you can prolong the life of your machinery and save electricity and money.