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Mining Publication: Technological Aspects of Solid-State and Incandescent Sources for Miner Cap Lamps
Keywords: Airflow Batteries Cap lamps Improving visibility Inadequate illumination 
 Temperature
Original creation date: September 2009
Authors: JJ Sammarco, JP Freyssinier, JD Bullough, X Zhang, MA Reyes
Peer Reviewed Journal Article - September 2009
Download PDF Document (0.11 MB)
NIOSHTIC2 Number: 20035976
IEEE Trans Ind Appl 2009 Sep-Oct; 45(5):1583-1588
Light-emitting diodes (LEDs) are emerging as viable replacements for incandescent (INC)-based cap lamps used in mining. The photometric and energy characteristics of these light sources differ in important ways. This paper describes the performance of LED and INC sources in cap lamps in terms of correlated color temperature, color rendering, light output, electric power, ambient temperature and air flow, and light source aging. Importantly, these characteristics can influence a miners ability to spot mining hazards thus impacting safety. Second, some of these characteristics interact with the operating life of the cap lamps battery power, such that differences between LED and INC sources can be magnified toward the end of a 10-h battery discharge cycle. Empirically, we have determined that after 8 h at an ambient temperature of 25 degrees C, the average light output of an INC cap lamp can decrease to about 69% of its initial value when powered by a lead-acid battery, and it can decrease to about 65% of its initial value when powered by a nickel-hydride battery. An LED-based cap lamp using a constant current drive circuit can maintain about 96% of its initial value when powered by a nickel-hydride battery. Real-world tests addressing the effects of ambient temperature and air flow on the light output of an LED and INC cap lamp were conducted in the National Institute for Occupational Safety and Health (NIOSH) Safety Research Coal Mine. The LED cap lamp yielded a vertical average illuminance improvement of approximately 9.5%, and the INC cap lamp yielded a vertical average illuminance degradation of approximately 4%. The differences between LED and INC cap lamps were further quantified by the calculation of "mesopic luminance" data that indicated for the same photopic luminance (i.e., as measured using a conventional light meter) the LED cap lamp could be up to 38% more efficient than the INC cap lamp with a lead-acid battery at the end of the 10-h driving cycle. Lastly, accelerated life tests were used to empirically determine light output depreciation as the INC light source age approached its useful life. There was about a 35% decrease in light output. This is quite considerable, particularly given that the light output will decrease an additional 30% to 45% over the period of a 10-h shift. The implications of the differences between LED and INC sources are discussed. This information is crucial in determining how visual performance could be affected for real-world conditions where batteries discharge during the work shift and as the light source ages. To date, only idealized conditions have been used for LED and INC cap lamp visual performance research.
Image of publication Technological Aspects of Solid-State and Incandescent Sources for Miner Cap LampsPeer Reviewed Journal Article - September 2009
Download PDF Document (0.11 MB)
NIOSHTIC2 Number: 20035976
IEEE Trans Ind Appl 2009 Sep-Oct; 45(5):1583-1588
See Also
Evaluation of Peripheral Visual Performance When Using Incandescent and LED Miner Cap Lamps
Evaluation of Visual Performance When Using Incandescent, Fluorescent, and LED Machine Lights In Mesopic Conditions
Illumination
Improved LED Mine Lamp Designs
Mine Illumination: A Historical and Technological Perspective
NIOSH Illumination Research Addresses Visual Performance Needs with LED Technology
Technological Aspects of Solid-State and Incandescent Sources for Miner Cap Lamps
Technology News 556 - The NIOSH LED Cap Lamp Provides Improved Illumination for Greater Safety in Underground Mines
Underground Coal, Metal, and Nonmetal Mine Illumination Systems for Improving Miner Visual Performance
Visual Performance for Incandescent and Solid-State Cap Lamps in an Underground Mining Environment
Visual Performance for Incandescent and Solid-State Cap Lamps in an Underground Mining Environment
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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