Danfoss supplied at VLT AQUA Drive FC 202 to run a new dewatering pump at an Arizona (U.S.) copper mine. (Photo: Danfoss)

Danfoss and a distributor, IEC Supply, supplied a low-voltage variable frequency drive (VFD) for a new 900-hp dewatering pump for a large copper mine in Arizona, U.S. The solution used the Danfoss VLT AQUA Drive FC 202 and hi-lo transformers to connect the drive to the power supply and pump motor.

The new pump replaced a 250-hp dewatering pump that daily moved as little as 600 gallons and as much as 6,000 gallons in the desert heat and sun.

The drive setup consisted of two parallel power modules of 450 hp each, on a common bus. One transformer sits between the power supply and the drive, lowering the voltage to allow the drive to operate.

The drive “enables the motor to operate over a wide speed range depending on how fast water needs to be pumped,” Danfoss reported. “An output transformer between the drive and the pump motor ‘steps up’ that VFD output voltage to supply the higher voltage motor,” it said. “Changes in the VFD output voltage based on pumping demand is detected by the motor, which then adjusts its speed accordingly.”

The solution was housed in a mobile trailer and could be moved where needed on the worksite.

The cost was substantially lower than the expense of a medium-voltage drive, Danfoss reported. “The solution saved the mine about 50% of total costs.”