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Purvis Industries


Posted on Thursday Jul 09, 2020 at 04:07PM in Electrical


Softstarters are another way for customers to start an electric motor, they are often the most economical solution for applications that only require controlling torque and speed during the motor start up. They perform this task by supplying the motor a reduced voltage during start up. They then slowly increase the voltage supply until the motor is running at full speed with full voltage. By starting a motor in this fashion, it not only reduces the mechanical stress in the system it also reduces the high in-rush current required to start the motor. This is done using switching devices inside a Softstarter such as thyristors or silicon-controlled rectifiers (SCRs). These switching devices turn off and on quickly adjusting the voltage output to the motor.

Soft Starter July 2020

Once the Softstarter has completed the initial ramp up to full speed, they switch the load to an integral or external bypass contactor. Removing the switching devices from the electrical circuit helps to improve overall system efficiency and reduce the heat generated inside an electrical enclosure. This feature can reduce or eliminate the need for any thermal management for an electrical enclosure.

Softstarters are ideal for applications where space is a concern since they are usually smaller than a comparable variable frequency drive (VFD). Softstarters are unlike a VFD as they can only control the speed of which a motor starts not the running speed of a motor.


For any questions please feel to contact one of our Triad Regional Application Engineer at [email protected] and we would be happy to assist you!

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