Energy-efficient centrifuges

CG AC drives offer very energy-efficient and reliable operation. They can work without brake resistors, which means energy generated by the braking motor can be re-used by the driving motor.

Driving motor and braking motor

Decanter centrifuges are often used for dewatering sludge in sewage treatment. The centrifuge consists of a drum and a screw conveyor that rotate independently of each other at up to 3,600 rpm, depending on machine and sludge type. Dewatering is achieved through the sludge being flung out through holes against the outer walls of the drum. The process uses two electric motors, one that powers the drum and one that brakes the screw conveyor so that it maintains a suitable speed.

Braking energy is re-used

When braking, energy is generated that is normally converted into heat and dissipated via brake resistors. CG's solution, however, allows the energy to be re-used instead. Thanks to the two Emotron AC drives being interconnected via a common DC-link, the braking motor’s energy is fed directly to the driving motor. The requirement for energy from the mains is reduced, and the cost of brake resistors is saved.

Case studies