Triplen Harmonics - An Overview

Triplen Harmonics are harmonics whose orders are multiples of three.  Thus the 3rd, 6th and 9th Harmonics are known as Triplen Harmonics.  These harmonics flow through the neutral conductor of Star connected transformers, causing heating.  This heating also affects cables and causes nuisance trippings of relays.

These are usually caused by power supply units for electronic appliances.  The power supply units are usually connected to only one phase.

Triplen Harmonics can be avoided by use of the delta connection for transformers and three phase loads.  Increasing the sizing of the neutral conductor is also a means of attenuating the effects of these harmonics.