While the Mine Site Technologies (MST) PED system was gaining acceptance in the US underground coal sector, the company was learning some useful lessons about frequency variation, which they were putting into practice at a new installation at MIM Holdings' Oaky No.1 mine in Queensland.
Over the past six months the mine paging PED system of MST has undergone remarkable acceptance in the US, particularly in the eastern states. Major US coal mining group Consol is now planning to install PED in all its mines. PED has been operating for a few years in the coal mines in Utah and Colorado, such as Twentymile and Sufco, but had not been installed at any mines in the eastern states.
According to MST business operations development manager, Denis Kent, this changed last September, with the successful installation at Turris Mine in Illinois.
"Since that installation it appears word has spread, and several other mines in Virginia and West Virginia also installed systems. These include Consol’s Blacksville and Buchannen mines, Riverton’s Kingston and Rock Springs mines, and Pittstons’ Laurel Mountain," Kent said.
One change that had to be made to the Australian designed product has been varying the PED frequency to minimise any potential interference from the mains power supply. North America utilises main power frequency of 60Hz as opposed to 50Hz in Australia.
Kent said knowing how well varying the frequency worked in the US in almost 20 installations enabled MST to vary the frequency of operation in Australia with confidence.
"However, the reason for the variation in Australia was quite different," Kent said. "The Australian requirement was because MIM’s Oaky No.1 mine wanted to install the PED system, following its success at Oaky North. However, the mines are adjacent, giving the potential for cross talk between the two mines along their lease boundaries. To overcome this the frequencies were varied to ensure no cross talk could occur, and the two systems could work independently."
Kent said this was an important option because as PED acceptance grows the issue of eliminating interference between mines next door to each other becomes important.
