The first of a new generation longwall sub-station designed by UK-based Baldwin & Francis is being installed at the BHP Elouera mine in New South Wales. The equipment was supplied and will be supported by locally based engineering company, Rutherford Power, which has an alliance with Baldwin & Francis for manufacture in Australia.
Baldwin & Francis has been manufacturing flameproof electrical equipment for use in hazardous areas of underground coal mines for 74 years in 26 countries.
Rutherford marketing manager, Chris Harvie, said the new technology introduced world's best practice in protection modules that would set the benchmark standard in Australia for personnel and equipment protection.
He said the equipment had numerous advantages including its compactness, easy maintainability and fitness for purpose. "All the componentry is ‘rack in, rack out', designed in a modular system."
Elouera electrical engineer, Igor Skofic, said the decision to purchase the new equipment was made on the basis of its modular configuration and the standard of protection it offered.
"We've set it up with a 1MVA transformer which is quite easily expandable to 2.5MVA," Skofic said. "We've got a couple of longwalls left in the current workings and the potential for another mine alongside it. We justified the capital on the basis that the new transformer could be moved over to a new or existing mine and upgraded to any configuration."
On protection systems, Skofic said: "If you have an earth leakage trip or a fault during operation it locks out the transformer outlet. Normally, site rules insist when an electrician finds such a fault that he not reset it until he unplugs the cable performs insulation tests to measure the cable for integrity.
"With this machine, as soon as you hit the reset button it will insulation test the integrity of the cable for you before restoring (or reclosing) power, which is a big safety advantage."
The 1MVA 3.3kV sub-station stands at a height of about 1.7m and is very compact.
Baldwin & Francis said the improvements on existing technology included an earth fault protection system, short circuit protection and advanced IS control and monitoring.
"The fail-safe neutral point monitoring ensures the neutral point is always connected," the company said. "The neutral point is restricted to give a maximum prospective fault current of 2 amps. Trip settings are down as far as 40mA at 3300V."
Equipment designed by Baldwin & Francis is tested in accordance with the Euronorm and IEC standards for flameproof equipment. Australia is in the process of aligning Australian Standards to IEC standards, which will rationalise current practice.
New flameproof equipment imported into Australia is currently subjected to further testing regardless of whether the equipment has been internationally certified.
Other features of the new equipment include phase sensitive short circuit protection to allow settings closer than conventional short circuit protection. Baldwin & Francis said the equipment would detect and trip at levels which are normally only detected by earth fault or overload protection. The system also has high integrity diagnostics and display systems.
