Peter Stepien and Richard Griffiths Senior R&D Engineer's with ResTech will present on the History of Earthing and the Impact on Coal Mining at the 2016 Engineers Australia Down to Earth Conference.
The use of earthing in electrical power reticulation has an interesting history. Initial power distribution systems did not deliberately reference the phase conductors to earth. While this allowed the system to keep operating for a single earth fault, there were adverse consequences. This led to the practice of earthing the supply, although this then led to other adverse consequences. Depending on the application, there was a bifurcation of earthing practices, with some systems solidly earthed through low impedance resistors and come loosely earthed through high impedance resistors.
The coal mining industry in Australia has converged to high resistance earthing. The supply is removed on the first earth fault to ensure that the fault is not escalated on the occurrence of a second earth fault. While this has safety benefits, there are challenges for the design of sensitive earth leakage protection. This includes the sizing of the earthing resistor and the reliable operation of protection relays. This is further complicated with the introduction of Variable Speed Drives (VSDs).
Peter's presentation will chart the history of earthing and how it has influenced the way that earth fault protection is implemented in coal mines, both in Australia and overseas.
About the presenter's Peter Stepien and Richard Griffiths