A Technique for Trolley Arc Reduction

Arcing which occurs at the trolley shoe is one of the leading causes of electrical accidents in the coal mining industry. Arcs occur if trolley contact is made or broken under load. Some of these incidents are caused by improper vehicle operation and others occur as a result of unstable tracking conditions. The arcing can be reduced by detecting the disconnect condition and snubbing the arc by responsive control circuitry. Once the disconnect has been completed, reconnection under load can be controlled with the same circuitry. A system of accomplishing this arc reduction is presented along with the results of a simulation used to test the effectiveness of the technique. Guidelines are suggested for incorporating arc- reducing control circuitry into mine track vehicles.