Harmonics - Attribute to Premature Failure of Distribution Transformer by Er. K K Morthy in Electrical Mirror Sep 2021
Synopsis:
Unlike Voltage-Sag, Voltage-swell, Interruptions, Voltage-unbalance Voltage-fluctuations, Transient conditions due to switching & lightening surges, etc. which are short lived, Harmonics is the component which shall neither die nor vanish from the Power Systems over a period of time unless otherwise harmonic filters are used. Harmonics are responsible for deteriorating the Power Quality.
Many Distribution Transformers installed in the Commercial & office complexes, Malls etc. fail prematurely. Most of the Distribution of Power Supply Utilities procure DTRs (Distribution Transformers) confirming to the IS: 1180(part-1)-2014[1] /IEEEC57.12.20- 2017[2] irrespective of the location, where they are to be installed at. The causes of failure are generally reported to as over-loading or short-circuit in L.T. network in the complexes etc. whereas the cause of failure of such DTRs is predominantly due to Harmonics only.
The Distribution Transformers confirming to IS:1180(part-1) -2014[1]//IEEEC57.12.20-2017[2] are manufactured to feed linear loads; however, they are also capable of feeding the non-linear loads which give rise to Harmonic distortion in sinusoidal wave to the tune of TDD (Total Demand Distortion) of 5% as stipulated in the BEE(BureauofEnergyEfficiency, India) Std. and IEEE Std.-519.-2014[3]
The authors has narrated the ill-effects of Harmonics attribute to premature failure of DTRs in this Article and has also suggested remedial measures thereof.
Key words and Acronyms:
DTR (Distribution Transformer),THD (Total harmonic Distortion),TDD (Total Demand Distortion),PCC( Point of Common Coupling) K-Type Transformer, Non-linear Load (whose impedance continuously varies with its applied voltage Cycle), PQ (Power Quality).