Voltage / Speed Control for Cased and Plate Axial Fans

Simple voltage control can be applied to the single phase Cased Axial Fans and Plate Axial Fans on Fanbuyer, by means of a Transformer Controller.

Using a transformer, the resultant voltage output to the fan motor is known as 'sinusoidal' and is as 'clean' as the mains input. The motor therefore does not suffer from electro-magnetically generated noise or additional self heating due to waveform harmonics. The downside is the cost, weight, and space required for the transformer.

Electronic voltage controllers rely on devices that switch the voltage waveform 'on' at a particular 'conduction angle' that is varied by the turning of a potentiometer. The advantage is low cost low weight and low space.

External rotor motors have high resistance rotors - which are necessary to enable voltage control. Most will work with electronic voltage controllers because the extra heat is lost to the airstream. It is only in larger sizes of external rotor motor that transformer control can become necessary.

Standard (internal rotor) industrial motors are not designed for voltage control and - depending on the type of fan - are likely to overheat once the voltage drops out of the normal tolerance band - e.g. a normal 230V means 216.2V to 253V in the UK.

Three phase voltage control by transformer is extremely expensive, because there is a transformer for each phase.

This article was published on Monday 06 December, 2010.