The benefits of using a soft starter on ac motors

Switching your ac motors to include a soft starter may result in an initial payout. Because of the reduced power consumption and maintenance, they will typically pay for themselves very quickly, and the benefits will be fully experienced from that point forward.


Switching your AC motors to include a soft starter may result in an initial payout. Courtesy: L&S ElectricThroughout the workplace in many industries, ac motors provide the backbone of much of the work that occurs. They work in the background, but without the power they provide, most industries would come to a grinding halt.

Although there are many considerations for ac motors, the starting method is something that should be looked into carefully. This is because motors will draw more current during the starting process. As a result of that additional current, damage could occur to the windings. Bringing the motor up to speed gradually can reduce that problem, and it is possible to do so through the use of a soft starter.

The purpose behind a soft starter is relatively easy to understand. It is a device that is used in conjunction with electrical motors, and it reduces the torque and the load temporarily during the startup process. Using such a device can help to reduce the surge of electric current during startup, as well as to reduce the mechanical stress on the shaft and motor. It may also benefit the electrical distribution network, and using one could extend the lifespan of the entire system.

The following are some of the many benefits associated with using soft starters at a facility. It is by no means a complete list, but it can certainly provide the information necessary to make a sound decision.

Contactor Replacement—One of the issues that is often associated with running ac motors without a soft starter is replacing the contactors. After upgrading to a soft starter, you will see an improvement in the operation and a reduction or elimination in the need to replace contactors. It can also reduce the noise associated with contactors during the operation of the motor.

Power Surges—Due to the draw of power that takes place at start-up with a motor without a self-starter, it can affect the performance of other systems in the facility. Including the soft starter helps to reduce the burden on the electrical system, equipment, and electrical devices throughout your location.

Reduce Maintenance—Using a soft starter allows the motor to run more smoothly during the startup process and reduces the need for maintenance. As a result, you will experience less downtime for the operation and save money as well.

Reduced Torque Transients—This is an issue that can result in damage to the motor. It involves sudden changes in the direction or magnitude of the torque load. As a result of that increased load, reduced torque transients could significantly decrease the lifespan of the motor. Applying use of a soft starter can reduce the torque load significantly during startup and limit any problems that are associated with it.

Switching your ac motors to include a soft starter may result in an initial payout. Because of the reduced power consumption and maintenance, they will typically pay for themselves very quickly, allowing users to experience the benefits fully from that point forward.

—David Manney is a marketing administrator at L&S Electric. This article originally appeared on L&S Electric Watts New Blog. L&S Electric Inc. is a CFE Media content partner. Edited by Erin Dunne, production coordinator, CFE Media,

Robert , United States, 05/31/16 01:00 PM:

The six times FLA inrush of a squirrel cage induction (by far the most common type) will not damage it. These motors are designed to be started across the line or in other words without the use of a soft starter. If you reduce the voltage impressed on a motor (with a soft starter for instance) you reduce the motor’s torque and although it may seem counterintuitive to those who don’t understand motor theory, this reduced motor torque can damage the motor. For instance, if you cut the voltage in half you reduce the torque to a quarter of its value. Using a soft starter can cause the load to be accelerated over too long a time resulting in overheated windings and a reduction in motor life. Soft starters are useful in some applications – when a conveyor can’t be started quickly for some reason. But to suggest that they be used in a manner that this article proposes is in my opinion not based upon good engineering practice and shouldn’t be recommended.
Anonymous , 06/01/16 05:20 PM:

I believe you would be hard pressed to show "reduced power consumption" associated with soft starter use. There are definitely maintenance advantages, however.
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