IEICE Electronics Express
Online ISSN : 1349-2543
ISSN-L : 1349-2543
Elimination of inrush current in parallel transformers by sequential phase energization
K. P. BasuAli AsgharStella Morris
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2007 Volume 4 Issue 5 Pages 147-152


Production of very high inrush currents in transformers during energization may create deep voltage sag causing malfunction to electronic and other loads. In high voltage power system star-delta transformers are generally switched in, one by one, producing inrush currents each time. The inrush current may be reduced by sequential phase energization of each transformer with neutral resistors.
This paper suggests that sequential phase energization should be carried out on the first transformer only after paralleling the delta secondary of all the transformers. This procedure eliminates inrush currents in all the remaining transformers without too much increase in the inrush of the first transformer.

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© 2007 by The Institute of Electronics, Information and Communication Engineers
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