Short circuit simulation of mining haul trucks operating on trolley systems

A typical mining facility uses off-road mining trucks to haul materials, such as coal, ore, and overburden from the pit to a stockpile where the material can be stored or processed. A conventional haul truck operates with diesel engine, adding considerable fuel expenses to the entire mining operation. The haul trucks are required to have fast speed especially for uphill condition with large haulage capacity in order to satisfy the productivity requirement. The main objective of designing a haul truck is to reduce the cost per ton of hauled material. Generally, this can be achieved by improving the system efficiency, reducing the maintenance, and making larger trucks. The electric haul trucks have these advantages due to elimination of the mechanical conversion. The efficiency can be further improved by using overhead trolley line feeding electric power to the truck as much as possible. By this way, the operation time of diesel engine is reduced and the corresponding maintenance is significantly saved. One of the major concerns of using trolley system is the availability of the trolley line, which affects the productivity directly since one or more trucks rely on the trolley line. Hence it is extremely important that the power system with the right short circuit capability be designed. This paper presents the simulation results for the short circuit studies for different conditions, which cover the maximum and the short circuit currents. The results are expected to give good reference on the selection of power system network parameters.