Yandi minesite recently introduced Komatsu 830E AC (electric drive) haul trucks, resulting in faster material movement, greater reliability, and reduced maintenance and costs.
A total of nine AC trucks have been in operation since January this year. These trucks complement the existing fleet of thirteen 730E DC drive haul trucks.
Yandi maintenance manager Darren Van der Wielen said the AC haul trucks had a number of advantages over the DC ones and were appropriate at Yandi due to the design of the pits and the required cycle time.
“DC drive systems in haul trucks are a mature technology and have limitations, many of which are eliminated by the use of an AC drive system,” he said.
“The average speed is greater in the AC system because it enables the trucks to traverse the ramps quicker and this results in a reduced haul cycle time.
“The AC electric drive truck inherently offers a greater retarding capability than a DC drive (around 9 km/h versus 3 km/h), which translates to higher downhill speeds. Komatsu indicate that AC has an 18% downhill speed advantage to an equivalent DC drive truck.
“The AC drive system also includes independent torque and speed control for each wheel motor, which optimises driveability and reduced tyre wear through control of wheel slip and slide.”
Darren said AC trucks were also found to have a 4 to 5% difference in mechanical availability over the DC trucks and lower operating costs due to less servicing.
“The AC system has fewer wearing components so there is reduced maintenance and overhaul scope, which translates into less machine downtime and cost,” he said.
“There is also no requirement to replace contactor tips, traction motor brushes or commutator repair, and wheel and motor overhauls require no armature re-work.
“In effect, with an AC drive system, many parts of the major electrical service works are eliminated compared to the equivalent service carried out on a DC truck.”
“In addition, the latest AC drive systems deliver the latest innovations in on-board and off board diagnostics. This enables display of diagnostic information to assist in immediate onboard troubleshooting of the system.”
AC trucks are also being introduced to Tom Price and Hope Downs this year.
This article was first published in Coastal News [September 2007, Issue No. 3] – Rio Tinto’s Coastal Division Newsletter.