Mine Electrical Power Systems. Transients Protection, Reliability Investigation, and Safety Testing of Mine Electrical Power Systems. Vol. V--periodic Inspection of Mine Electrical Power Systems.
This report presents the results of an investigation into the feasibility of periodically measuring parameters of the insulation for a mine electrical power system to detect incipient faults. The variety of insulation parameters evaluated included insulation resistance, dissipation factor, power factor (versus applied voltage), current harmonics, leakage current, infrared radiation, as well as certain circuit breaker parameters and tests. Apparent inconsistencies in data were identified as the result of environmental effects, primarily temperature and relative humidity. A series of environmental tests were conducted to develop correction factors that allow reference of measured parameters to standard conditions. A portable data collector was developed to aid in the accurate collection and analysis of laboratory and field data. It was concluded that insulation deterioration can be measured and failure predicted with reasonable confidence, and that most of the tests are impractical in the field. Infrared sensing, insulation resistance, and dissipation factor are the best insulation field tests.