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Distinguishing motor starts from short circuits through phase-angle measurements.

Authors
Yenchek-MR; Cawley-JC; Peterson-JS; Kohler-JL
Source
NIOSH 1997 Mar; :1-15
NIOSHTIC No.
00238990
Abstract
An investigation was undertaken to investigate the characteristics of high voltage underground electrical mining equipment motor start and short circuit waveforms. The aim of the study was to determine a method for providing short circuit protection without intentional time delays to account for motor starts. Computer simulations of power systems identified the requirement for accurate and rapid detection systems. Analyses of high voltage longwall coal mine power systems were conducted using commercial power system analysis software. Distribution voltage, transformer impedance, power center location, and motor size affected magnitude of short circuits and motor start currents. Phase angles between voltage and current were longer for motor starts than for short circuits. A prototype with an induction motor was developed and tested in the laboratory. Minimizing the intentional time delays in short circuit protection will help ensure temperatures of ignition thresholds for gas and dust are not be exceeded on energized electrical apparatus surfaces.
Keywords
NIOSH-Author; Mining-industry; Underground-mining; Mining-equipment; Electrical-equipment; Electrical-properties; Electronic-circuits; Voltage-regulation
Publication Date
19970301
Document Type
Numbered Publication; Report of Investigations
Fiscal Year
1997
NTIS Accession No.
PB97-156723
NTIS Price
A03
Identifying No.
(NIOSH) 97-120; RI-9638
NIOSH Division
PRL
Source Name
National Institute for Occupational Safety and Health
State
PA
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