Improvements in fault current calculation techniques for dc systems

Journal Article · Sun Sep 01 04:00:00 EDT 1985 · IEEE Trans. Ind. Appl.; (United States)

DOI:https://doi.org/10.1109/TIA.1985.349515· OSTI ID:5993719

Tylavsky, D L

Since 1970 at least 12 men have died from underground coal-mine fires which were started due to undetected high-resistance faults on trolley systems. Methods which have been proposed to determine these dc fault currents more accurately involve the assumption that the magnitude of the fundamental-component current on the ac side of the rectifier is equal to the magnitude of the current on the dc side of the rectifier. Since this assumption breaks down when the fault occurs at the terminals of a rectifier, a new nonlinear equation set is proposed which eliminates this assumption. The equation set is formulated to account for dc fault current contributions from dc machines and threephase bridge rectifiers. Newton's method is used to solve the set of nonlinear equations. The use of rectangular wave form for all voltage variables and elimination of current as a variable provides more reliable and faster convergence than previous methods. A new phenomenon is identified in the results presented. Under certain fault conditions, dc motor voltages may be of sufficient magnitude to reverse bias electrically close bridge rectifiers and hence prevent them from contributing to the fault current.

• Research Organization: Department of Electrical and Computer Engineering, Arizona State University, Tempe, AZ
• OSTI ID: 5993719
• Journal Information: IEEE Trans. Ind. Appl.; (United States), Journal Name: IEEE Trans. Ind. Appl.; (United States) Vol. IA-21:5; ISSN ITIAC
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
013000* -- Coal
Lignite
& Peat-- Transport
Handling
& Storage
CALCULATION METHODS
CURRENTS
DETECTION
DIRECT CURRENT
ELECTRIC CURRENTS
ELECTRICAL EQUIPMENT
ELECTRICAL FAULTS
EQUIPMENT
HAULAGE EQUIPMENT
MATERIALS HANDLING EQUIPMENT
MINING
NONLINEAR PROBLEMS
OCCUPATIONAL SAFETY
RECTIFIERS
SAFETY
UNDERGROUND MINING