Portable power supply for coal mines

The concept of power supply for a mining operation, therefore, is one which provides for a reliable supply to the main distribution point in a mine, from which power is then distributed to all the key loads in the operation.

The overall consumption of the mines is usually fed via a main substation located in the most favorable site with regard to power requirements on the one hand and the configuration of the electricity distribution grid which it taps on the other. As a rule, a dual system of power supply, i.e. a main and a standby system, should be provided.

In addition to striking differences in the basic design, mine power supply systems also involve a number of special features relating to the installation of the system and necessitated by particular operating conditions deriving from environmental factors, difficult maintenance and repair operations, and special safety considerations.

The basic data, to be provided by the utility supplying power to the mining operation, refer to the resistance and inductive components of the network up to the main substation, both at the start of the operations ("present" conditions) and over time, corresponding roughly to the depreciation life of most power facilities in the mine.

The general conclusion is that, in a typical mining operation, a 6 kV system will cover practically all the immediate requirements of the major loads and of the pit supply network, for which, moreover, standard equipment is readily available.

Different voltages are used for mine supply systems in different countries, e.g. 2, 3.3, 4.4 and 5 kV, and up to 11 kV in non-gassy pits. For mines with explosive atmospheres the most appropriate voltage will be 6 kV.