ANALYSIS AND FORECAST OF ACCIDENT RATE OF 6 – 10 KV DISTRIBUTION GRIDS AND POWER CONSUMERS IN THE MINING SECTOR

The main types of accidents in 6–10 kV power supply systems of mining enterprises are considered, such as short circuits, single-phase earth faults, phase failures, with their percentage relationships established. Mining enterprises are divided into three groups: open-cut mining enterprises (quarries and open coal pits); enterprises for extraction of minerals by underground method (underground coal and ore mines); mining & processing enterprises (concentrating factories, alumina plants, fertilizer production enterprises). The analysis of the accident rate of power supply systems of mining enterprises carried out for the period from 1995 to 2015 makes it possible to trace the dynamics of the above types of accidents and determine their most common form — single-phase earth fault. Over the above period, in the 6 – 10 kV power supply systems of quarries and open coal pits, underground coal and ore mines, and mining & processing enterprises, the share of single-phase earth faults was found to be within the following ranges: 65 – 76%; 60 – 69%; 58 – 67%, respectively. The greatest increase in accidents during the period under review was observed in 6 –10 kV power supply systems of quarries and open coal pits; with the total accident rate having risen with a factor of 3.21 from 1995 to 2015. The accident rate growth factor for underground coal and ore mines, and mining & processing enterprises amounted to 2.06 and 2.72, respectively. The changes are shown in specifi c types of accidents and general accident rate in the systems of electricity supply to quarries and open pits, underground coal and ore mines, and mining & processing enterprises. It is established that in the 6 – 10 kV power supply systems of the above-mentioned mining enterprises, the changes in single-phase earth faults and general accident rate are described by linear equations. On the basis of established patterns, a forecast is made of the change in the accident rates in power supply systems of the mining enterprises under consideration up to the years 2020 ÷ 2025.

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