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Mining Publication: Technology News 474 - A Passive Means to Detect Hot Trolley Insulators
Keywords: Electrical insulation Temperature sensors Thermal detection Trolley wire
Original creation date: August 1998
Authors: National Institute for Occupational Safety and Health
Technology News - August 1998
Download PDF Document (0.06 MB)
NIOSHTIC2 Number: 20000572
Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Technology News 474, 1998 Aug; :1-2
Electrical Trolley systems are used for both mineral haulage and movement of personnel and supplies in nearly 50 U.S. mines, mostly in southwestern Pennsylvania and West Virginia. These systems use a trolley wire, energized at 300 or 600 V dc, to power vehicles constrained to run on a network of permanently installed steel track. The bare copper trolley wire along with a feeder wire are suspended about every 6 m fro insulators that are anchored into the roof by bolts. The insulators prevent current from flowing to the grounded return rack via the overlying strata. Coal and rock dust accumulations, as well as acidic drainage and condensation, may jeopardize insulator integrity. Leakage currents from the trolley wire into the roof strata can heat the insulator, as well as the immediate area in which the suspended bolt in anchored. If not detected and corrected, this may result in ignition of roof coal and a catastrophic mine fire. An insulator and surrounding strata that are subject to leakage currents maybe discolored, having an odor, or exhibit no physical evidence of deterioration. Leakage can be confirmed through voltage measurements across the insulator. However, this can be a time-consuming tedious task considering the thousands of insulators distributed over miles of haulage way. A portable infrared detector can be used to scan for heat on the insulators and in the roof form a low-moving vehicle. This can be effective when done regularly, but this method cannot detect impending failures between examinations. An insulator, integrally designed to give some indication of the presence of leakage currents, could be detected and replaced promptly.
Image of publication Technology News 474 - A Passive Means to Detect Hot Trolley InsulatorsTechnology News - August 1998
Download PDF Document (0.06 MB)
NIOSHTIC2 Number: 20000572
Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Technology News 474, 1998 Aug; :1-2
See Also
Derating Factors for Round and Flat Mine Trailing Cables
Detection of Downed Trolley Lines Using Arc Signature Analysis
Distributed Measurement of Conductor Temperatures in Mine Trailing Cables Using Fiber-Optic Technology
Electrical Fault Detection on Downed DC Trolley Lines
Motor Monitoring System for a Continuous Miner
Overview of Mine Fire Detection
A Passive Means to Detect Hot Trolley Insulators
Technology News 456 - A Fault Detection Neural Network for DC Trolley System Protection
Use of Infrared Sensors for Monitoring Methane in Underground Mines
Wireless Sensor Network with Methane Gas Cloud Detector and Absolute Pressure Sensor
Page last reviewed: September 21, 2012
Page last updated: September 21, 2012
Content source: National Institute for Occupational Safety and Health, Mining Program
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