Universal Motor - An Overview

Universal Motors are motors which run on both AC as well as DC power.  These motors find wide application in household electric appliances such as mixers, blenders.

The small size, high power and speed of universal motors make them ideal in these applications.  The Universal Motor is the motor of choice for washing machines as they can be used to agitate the drum by easily reversing direction. 

A universal motor is a dc series motor which usually has some modifications which enable it to run efficiently on AC as well.  Running the motor on AC leads to eddy currents being developed in the core of the motor.  Hence, the core and poles of universal motors are made of laminated sheets.  The windings of the motors are made thicker to reduce the reactance.   

Like all DC machines, universal motors suffer from the effects of commutation such as sparking.  Hence, universal motors are used mainly below 1000W.  The high speed of the universal motor enables it to deliver a higher power even while having a small size.  Universal motors are usually kept coupled to the loads such as gears or blowers as they tend to run at very high speeds on no load conditions. 

Speed Control is usually done by Electronic means.  

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