Stray dc transit currents and their effect on transformers

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:83083

Sheil, G A; Singh, B N ^[1]

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1. North York Hydro, Ontario (Canada)

Stray DC currents from transit systems have been known to create problems for electrical utility transformers. An overview of the effect of DC currents generated from the transit system owned and operated by the Toronto Transit Commission (TTC) on North York Hydro (NYH) transformers has been presented. The paper compares the early results from the time the negative DC rail was solidly tied to the NYH neutral with those obtained after mitigative measures were put in place. The mitigative measures were aimed at increasing the electrical isolation of the negative DC rail from ground. Results indicate that the mitigative measures did reduce the level of stray DC on the NYH transformers along the subway lines. However, present DC levels are such that the cyclic transformer noise is still very audible. Concerns regarding core heating, lamination displacement, and primary winding loading still exist. Further mitigative measures and solutions to the problem have been proposed.

• OSTI ID: 83083
• Report Number(s): CONF-940222--
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
DECOMPOSITION
DIRECT CURRENT
ELECTRIC POTENTIAL
ELECTRIC UTILITIES
ELECTRIC-POWERED VEHICLES
HEATING
LEAKAGE CURRENT
LUBRICATING OILS
MASS TRANSIT SYSTEMS
NOISE
POWER DISTRIBUTION SYSTEMS
RESPONSE FUNCTIONS
SAFETY ENGINEERING
SERVICE LIFE
TRANSFORMERS