Basic Difference between Soft Starter & Variable Speed Drive

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It is the starter as the name suggests which ‘start’ motors. They are also responsible for stopping, reversing, accelerating and protecting them. And it is the electric motor which drives all of the equipment irrespective of the size; whether it be a small fan or as big as mining equipment piece.

The motor and the inbound utility line have a device called the soft starter placed between them for regulating the current amounts fed to the motor. Soft starters ensure that the AC induction motors speed up in lesser amounts as compared to a traditional motor starter. This in turn leads to lesser drawing in of the electric current by the motor. Because of the reduced voltage, there is reduction in torque and this helps in a smooth and easy start. Every type of DC and AC motors include soft starters. They go more often with AC squirrel cage induction motor due to its toughness, simplicity and dependability.

Soft starters offer the features of overload protection and controller. Controllers switch the electric motor to the on and off stage while overload protection ensures that the motor does not draw too much current and ‘burn out’ due to overheating. Soft starters, hence, perform two important functions and they are to prevent the power distribution system from getting overloaded and secondly preventing unwanted equipment wear and tear by lessening the starting torque. There are five different types of soft starters in the market such as the Primary Resistor, Part Winding, Auto Transformer, Wye Delta and Solid State. Crompton Greaves soft starter dealers stock all the varieties to suit the differing requirements of their customers.

Another device that can perform similar functions is the variable speed drive. However, some basic differences exist between the variable speed drive and the soft starter. In case of the soft starter the motor starts at decreased voltage and the soft starter comes into play when the motor touches full speed. In case of variable speed drive, the motor speed can be varied while it is functioning by controlling the output frequency from the variable speed drive.

To put it simply, the soft starter is useful if the motor has to be ramped up to full speed on starting it but in case there is a need for variation then it is the variable speed drives that prove useful. The extra cost needed for its installation will be recovered through the energy savings obtained thereafter. There is an option for replacing soft starters with variable speed drives if the need arises and this fact will be vouched for by variable speed drive panel dealers too. This can happen if a need arises at a later stage for varying the motor speed and this will not be fulfilled by a soft starter. One thing for sure is that the installation of a variable speed drive will definitely enhance your production. Variable speed drives are ideal devices for fan or blower application and also on a pump besides other applications. It has to only be borne in mind to source them from reputed dealers.