Phase Inverters and VFDs (Variable Frequency Drives)

Phase Inverters - VFDs scored the poor to moderate in all categories of our testing and research.  VFDs, also known as variable frequency drives can be used to control motor only type of loads.  They cannot be used for any type of non-motor 3 phase load.  They are not good for welders, computers, battery chargers, ovens, electronics, etc., and could burn out this type of equipment if attempted to power these other applications.  

Phase Inverters and other types of VFDs are very sensitive in their circuitry and can be damaged by voltage spikes and lightning strikes. 

This type of phase converter takes a sine wave, chops it up and spits out a somewhat choppy synthesized 3 phase sine waves - their output harmonic distortion tends to be greater than a few other types of phase converters.  Most of these types of units on the market were limited in the amount of power they could produce.  Thus from all the models that we found, if you need to supply a lot of 3 phase power - this type of phase converter is not appropriate.  When attempting to use a VFD to produce 3 phase power from single phase also eliminates its ability to vary frequency of power output and thus it cannot vary the speed of a drive it was meant to run. Also due to their complex electronics they are much more expensive and there is a limited number of locations with the ability to repair these.  This can cause extended and costly downtime in the event of damage.  The sensitive nature of their electronics causes their lifespan in the field to be much shorter than what the companies hawking VFDs and Phase Inverters claim they are capable of.   

There are phase converters types that scored a much higher score than VFDs and Phase Inverters.  Read our Phase Converter Comparison Chart to see which models scored well in each category.

Remember that not all phase converters are manufactured to the same high quality standards.  Click here to read our Phase Converter Purchasing Checklist for guidance in selecting a quality product from a quality company.