The effect of DC current on power transformers

Zeimer, Ashley Karl (2004) The effect of DC current on power transformers. [USQ Project] (Unpublished)


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Power transformers are an integral part of almost all electrical transmission and
distribution networks. Their reliable service is of the utmost importance in modern
society which is dependent on a constant electricity supply. There are a range of
factors that can hinder the operation of a power transformer. This dissertation presents
the results of investigations into one of these factors through an analysis of the effect
that direct current has on the operational characteristics of a power transformer.
There are a host of adverse effects that can accompany the presence of a direct current
in a transformer's windings. The predominant effect that is witnessed is half cycle
saturation. This leads to increased harmonic distortion, increased reactive power
losses, overheating and elevated acoustic noise emissions.
Direct current can be found in a transformer's windings as a result of imperfections in
connected equipment and also due to magnetic disturbances of the earth's field. Tests
conducted indicate that personal computers are a potentially significant source of DC
when a large number of units are connected to a common point of coupling. Similarly
the possibility exists for AC and DC induction motor drives to contribute sizeable
quantities of DC Bias.

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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Electrical, Electronic and Computer Engineering
Date Deposited: 11 Oct 2007 00:14
Last Modified: 02 Jul 2013 22:30
Uncontrolled Keywords: DC current, power transformers, magnetising characteristics, harmonic distortion behaviour, hysteresis characteristics
Fields of Research (FoR): 09 Engineering > 0906 Electrical and Electronic Engineering > 090603 Industrial Electronics
09 Engineering > 0906 Electrical and Electronic Engineering > 090699 Electrical and Electronic Engineering not elsewhere classified

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