Dist.Trans. Handbook (1).pdf - Distribution Transformer...

Distribution Transformer
Handbook
T H I R D E D I T I O N

Distribution Transformer Handbook
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COMMENTS
If you have comments on this handbook, or suggestions how we
might make it more valuable for you or your company, please call or
write:
Alexander Publications
177 Riverside Avenue #922
Newport Beach, California 92663
Telephone: [phone] or [phone]
Fax: [phone]
E-mail: [email protected]
Third edition
Fourth printing: October 2006
Each printing incorporates minor improvements.
© Alexander Publications 2001. All rights reserved.

Introduction i
FOREWORD
I am pleased to introduce our handy reference on distribution
transformers for lineworkers. This practical handbook provides quick
access to essential information for immediate use, whether in the field
or in the shop.
We have tried to select the most commonly required information,
then present it in an easy-to-read format, to make this guide a useful
and reliable reference document.
Richard Alexander

ii Distribution Transformer Handbook
ACKNOWLEDGEMENTS
This handbook is a supplement to other excellent resources on
transformers currently available.
Among the materials consulted while preparing this book are:
ANSI 05.1 Specifications and Dimensions for Wood Poles , ANSI
C57.12.70
Terminal Markings and Connections for Distribution and
Power Transformers , ANSI C57.105 Guide to Three-Phase
Transformer Connections, Distribution Transformer Manual
by
General Electric, RUS++ by Alexander Publications, and Transformer
Connections
by General Electric.
Product literature and application advice were provided by ABB
Power T&D Company Inc., Alec Wolowidnyk, Arkansas Electric
Cooperatives, BC Hydro, Cooper Power Systems, ERMCO, General
Electric, Howard Industries, Northeast Utilities, Northeastern JATC,
Northwest Lineman College, Puget Sound Energy, Solomon
Corporation, Southern California Edison, and Tommy Edwards.
We gratefully acknowledge the assistance from each of these
sources.
WARNINGS
Energized transformers and live distribution lines present the risk of
electrical shock. All work on this equipment should be performed
only by qualified specialists. The connection diagrams, tables, and
other data in this handbook are intended to be aids for field
personnel. This material does not replace the extensive training
necessary to safely work with transformers in service.
This handbook describes work practices which are accepted by
most utilities, but some may not apply to you. Always follow your
company’s established safety procedures and work practices.
NOTICE
The publisher does not assume any liability with respect to the use of
any information in this publication.

Introduction iii
TABLE OF CONTENTS
Chapter 1 Transformer Concepts
Introduction to Distribution Transformers . . . . . . . . . . . . . . . 1
The Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Power Triangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Transformer Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Transformer Taps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Transformer Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8