Published in March 2006 Australian Longwall Magazine

The project presented several unique electrical design challenges due to the 410m face width.

The three by 1MW rating of the armoured face conveyor (AFC) drives resulted in a very high power demand level and also significant voltage drop during starting and peak loading events on the AFC.

Ampcontrol, with assistance from Joy and Ulan, completed detailed power studies and load flow analysis of all possible scenarios to ensure reliable operation of the electrical system during all operating modes. These studies resulted in several significant design improvements to the electrical equipment to ensure robust operation.

“With Ulan being the first longwall face in Australia to operate at a width of 410m, and a step change in AFC capacity, Ampcontrol needed to ensure all aspects of the electrical system were analysed and strengthened accordingly,” said Ampcontrol group operations manager Keian Barnard.

“I am very happy with the final outcome of the design process and have absolute confidence that Ulan has received a robust electrical package that will provide reliable operation for the effective life of the longwall equipment.

“This process highlighted to us that the industry has reached the design limits for AFCs powered by 3.3kV motors, the next step will have to be a step change electrically if the industry trend continues to ever-wider longwall faces. Ampcontrol is already exploring alternative designs for wider faces and we are of the belief that it is only a matter of time before the capacity demands of longwalls will result in this change,” he said.

In another Australian first for the Ulan longwall project, the 6.25MVA GNAN transformer designed by Ampcontrol used a water-cooling manifold as a method of dissipating the heat from the surface temperature of the transformer.

This is the first time this has been used in Australia as a method of ensuring the transformer does not heat the surrounding air to unacceptable levels. Similar methods have been used overseas with oil-filled transformers, however Ampcontrol is the first to utilise this technology with dry-type transformers.

The cool water is pumped from the mine’s water supply and after being channelled around the surface of the transformer, the resulting heated water is used as waste water to spray on the coal face. The water-cooling manifold resulted in approximately 10% reduction in surface temperature and will result in a lower temperature surrounding the substation.

The Ampcontrol-supplied package includes two 6.25MVA, 11kV/3.3kV/1050 kV substations complete with water-cooling manifolds; four 3.3KV flameproof distribution control boxes with the latest Ampcontrol Integrated Protection equipment and integrated PLC/SCADA control systems; two iMAC AFC signalling and face lockout systems; two VoiceCom face communications systems; two Gasguard gas monitoring systems; and two 3.3kV IP66 pump distribution control boxes.

Ancillary equipment include face lighting, 3.3kV power cables, control cabling, communications and control interface to the Eickhoff shearer and Joy roof support control system.