Underground » Health and Safety
This project investigation commenced as a follow up to the original work undertaken into "Close Aspect Lighting" at UNSW. Close Aspect Lighting emphasised the need to provide low level non glare lighting installations around mobile machinery in underground coal mines. Of particular interest was lighting in the vicinity of continuous miners and shuttle cars.
Close Aspect Lighting was originally based around the use of high intensity incandescent lighting reflected from the mine strata. Coal has a reflection coefficient of approximately 5% which would provide sufficient reflected light for suitably adapted eyes to see to sufficient standard in areas of illumination of less than approximately 5 lux. This would ensure that equipment could be seen and "slip and trip" hazards would be quite visible to any miner operating in and around the mining equipment. This technique was well demonstrated and its value clearly obvious.
One of the major drawbacks of this original approach was still the need for a light source of high wattage (around 100 watts at least), operating at a voltage of at least 100V AC and consequently generating a high level of heat which needed to be addressed in the final physical design of the luminaire.
As work commenced on this project it became clear that research had moved rapidly ahead in the area of new light sources which addressed a number of problems described above.
An emphasis was now being placed on the generation of light from semiconductor sources rather than from filament or discharge sources. The impetus for this was a need for compact, simply constructed and long life light sources that could produce low level light in a range of environments including hazardous environments.
As an investigation was commenced into this area and its applicability to underground coal mining it was discovered that this approach to lighting fulfilled many or the requirements of Close Aspect Lighting plus some added benefits.
This form of lighting is often referred to as "cold lighting" and uses light emitting diodes or electroluminescent panels to achieve the same if not better illumination levels than the original close aspect approach. It also requires minimal current to generate equivalent light, hence it could be made intrinsically safe, it has a useful life of many thousand's of hours, generates no heat, is very efficient - around 90%, the basic material cost is quite competitive and can be adapted to almost any application where not only is close aspect lighting useful but can act as a safety enhancement to any installation and in a specific form can act as a projector light providing sufficient lighting to act as task lighting in addition to the standard caplamp.
This report details the investigation and testing of this approach.
Numerous forms of the light sources were tested including sheet, ribbon and specific LED lighting. All have very important prospects for use in a mining environment provided the cost of the luminaire installation can be made competitive and the approval for intrinsic safety is accomplished. If the current costs are not competitive recent advances indicate that with added interest from other industries the prices will reduce in the short term. In the short term the light output levels of this approach can only increase. In summary, every effort should be made to pursue the application of "cold lighting" to the underground mining environment. Its flexibility and safety implications should now allow lighting of almost any aspect of the underground mining environment.