How to choose speed controllers for AC motor?

Now around the world are using the speed controllers to control and drive their electric motor such as frequency inverter and soft starter.This speed control get a good reputation to reduce electricity cost and high efficiency to drive electric motor.

Speed controller is low maintenance and have a long life span.It easy to install and user friendly to setup and setting the parameter.

The wiring for power supply and control circuit is not so complicated like conventional motor control.This post i want share some basic aspects for choose the suitable ac motor speed controller that we must consider when to buy or install it on our application.I hope this information can be the basic guideline.

Criteria to choose a speed controller

1) Types of motor.

– Consider the types of motor when you plan to install the speed controller.Basically speed controller can drive with any types of AC motor without any special pre-caution.

But for more better application,we should choose the motor with high efficiency and power factor.If we used a low power,the suitable speed controller types is synchronize motor controller.


2) Types of Load

–  Basically the speed controller is suitable for drive the pump,air-compressor and fan or blower.It can reduce the high in rush current during starting operation.Consider the types of load for our application to avoid not suitable with the speed controller specification.

Manufactures made a different types of speed controller depend on application and type of load.We must consider the starting torque,ramp out and others issued for the motor functions.


3) Types of application

– Please consider our speed controller types with the machine or equipment application such as for air-compressor,cooling system,rotating equipment,blower and others because it will effected the wiring design and additional accessories for motor control and  protection.


4) Brand of speed controller

– This issued also effected for our decision to purchase the speed controller.Please consider the good brand and familiar with our application.Also please check the spare part still available or not,their services center,technical support and warranty.

Normally for the good brand,they provide the detail manual user,technical support,spare part and warranty for their speed controller.From my experience,the brand normally in my listed such as ABB,SCHNEIDER,DANFOSS,FUJI ELECTRIC,TOSHIBA,AB,YASKAWA,OMRON,MITSUBISHI and BALDOR


  1. haitham hashim says

    The subject of important topics be thankful if he can publish maps Electrical,thanks

  2. Makwana Bipin says

    thanks this electrical instrument

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