BART is a dc-powered transit system that uses its running rails for traction-current negative return. The use of the running rails as part of the electrical-traction circuit presents the engineer with two conflicting electrical requirements. First, the negative return must, at times, be connected to earth and structures to control electrical-fault currents and to limit voltages. Second, the negative return must be electrically insulated (isolated) from earth and structures to minimize stray current and the resultant corrosion. To satisfy both of these requirements, BART developed insulated rail fasteners and diode grounding. This paper describes these system features as well as recent efforts to improve the rail-fastener insulation and negative-return grounding.

Subject
Electric current, Circuits, Steel structures, Substations, Insulation, Voltage, Arrays, Rails, Grounding, Stray current, Fasteners, Negative return, Fault currents
Keywords:
corrosion, electrical potential, electrolyte, dc powered, grounding diode, leakage current, negative return, rail fastener, running rails, stray current
© 1994 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1994
Association for Materials Protection and Performance (AMPP)
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