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 more accurately determine these dc fault currents 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 use of rectangular form for all voltage variables and elimination of current as a variable in the equation set 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.
|Original language||English (US)|
|Title of host publication||Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)|
|Number of pages||7|
|State||Published - 1984|
ASJC Scopus subject areas
- Electrical and Electronic Engineering