The underground coal mine is one of the most difficult lighting applications. It is a low reflectivity, low contrast, high temperature, and high corrosive environment. With the use of LEDs in place of traditional incandescent lamps, coal mine lighting application has become less challenging.
The 20W LED lamps come in two designs: - the round shape ones are for general lighting in the underground coal mine while the square ones are for long distance lighting inside the tunnels. Because of the low reflectivity in coal mines, the output of light sources needs to be much higher. With luminous flux of 104 lm warm white to 130 lm cool white, Oslon SSL is the ideal choice for this application.
“We have chosen Osram’s Oslon SSL LEDs for their high reliability and efficiency,” said Zhong-hua Li, Chairman of the Board of Shenzhen General Technology Co. Ltd., the company which builds these coal mine lamps. “More importantly, the light output of these LEDs is high enough for good designs. The average luminance is 82Lx, compared to 45Lx of the previous incandescent lamps. With the use of advance optics, we are able to reduce glare to a minimum in this low contrast environment.”
Apart from high efficiency, these Oslon SSL LEDs excel in all the stringent tests for applications in the coal mine environment. They include the coal mine safety certification, explosion-proof certification, salt spray, waterproof testing, impact test and the 1000-hour burning test.
“The use of LEDs in coal mine lighting is definitely taking off,” said Kai-chong Cheng, Senior Marketing Director APAC of Osram Opto Semiconductors Asia Ltd.. “We are very pleased that our Oslon SSL LEDs are being chosen to be used in the coal province of China. These are the most compact 1 W LEDs on the market. As LEDs do not use any glass envelope and cannot break, we hope the use of these LED lamps will reduce hazards for the people who work underground.”
LEDs are robust because they do not have a glass envelope or filament that can break. Besides, they can provide useful light in excess of 50,000 hours of operation as compared to about up to 3,000 hours for an incandescent bulb. The maintenance interval will be reduced from once in every three months to once a year. According to a study by the National Institute for Occupational Safety and Health (NIOSH) in the USA, the greatest percentage of accidents (53%) happened during the maintenance and repair work of light bulbs or light fixtures. The longer life and packaging (no glass envelope) of LEDs would decrease the exposure to these hazards.