VSD cuts baler energy costs

The company wanted to improve the energy efficiency of the baler, which uses a motor-driven pump to compress the hydraulic fluid. This motor originally ran at a fixed speed. When hydraulic pressure reached the set point, excess fluid was diverted through a pressure relief valve, wasting energy.

Drives Alliance member, Inverter Drive Systems (IDS), installed a 30 kW ABB general purpose drive, ACS550, as well a pressure transducer. Andy Crocker of IDS says: "The pressure transducer gives a 4-20 mA output that is proportional to the pressure. On the drive, we have the set point at just below the valve opening pressure. When the hydraulic ram is moving and fluid is therefore flowing, pressure drops, so the drive speeds up the motor to maintain pressure. When the ram is not moving, pressure rises so the drive slows the motor.”

This arrangement means the drive can always give the pressure and flow needed without opening the relief valve and wasting the pressure in the fluid.