Using Phase Shifting to Cancel Harmonics

[Dave Loucks]

Putting some loads downstream of transformers that have different phase shifts is a well-known method of cancelling harmonics.  But how much cancellation?  And what amount of phase shift should I use -- 15 degrees, 20 degrees, 30 degrees, 45 degrees?

To answer that question I created a calculator that allows you to select from 1 to 4 parallel transformers, each with programmable kVA rating and phase shift, and measure the amount of harmonic attenuation you might see in such a configuration.

Take a look at the 9-minute tutorial video on how these programs work and download them from the links below.


Attached a later version (V3) to add 17th & 19th harmonics and clean up some errors that occur if you selected 3 or 4 parallel transformers.