Review of LED based cap lamps for underground coalmines to improve energy efficiency as compared to other light sources

This paper deals with the energy savings in cap lighting system of underground coalmines using Light-Emitting Diodes based cap lamp as compared to other light sources. The purpose of the paper is to ensure numerous complex and interrelated factors that must be considered to design and implement a LED based efficient lighting system suitable for underground coalmines which will satisfy human needs for good vision and comfort. The workers of mines are very much dependent on visual cues to recognize underground mining hazards. On the other hand, illumination plays a critical role in miners' safety. Some hazards are located in the miners' peripheral field-of-view offaxis from 10° to about 60° or on-axis 0°. The objective of this paper is to enhance the visual performance using solid-state cap lamps with LEDs as compared to CFL or incandescent bulbs commonly used in miners' cap lamps. Recent research has indicated that an increased short-wavelength content of the spectral power distribution of LEDs relative to incandescent lamps improves peripheral visual performance for low-light conditions. As LED produce light at required wavelength hence less energy is consumed by the lighting fixture as compared to the white light produced by incandescent bulb or CFL. The conversion of electrical power into light power is much more in case of white and red LEDs as compare to blue one. In the present paper different issues related with incandescent bulb, CFL and solid-state LED have been discussed and their performance in respect of underground coalmines has been analyzed. Furthermore, choice of type of LED has been discussed for a lighting system designed for underground coalmines.