Drive saves 70% energy in hydraulic system
Hydraulic systems typically waste energy by continuously circulating fluid despite only carrying out work in short bursts.
In addition, the pressure of a hydraulic system is normally provided with a positive displacement pump, which offer far less potential to save energy than the more common centrifugal pump.
However, steel manufacturer Corus, based in Deeside, recently installed an ABB industrial drive that achieved a significant energy saving by retrofitting the existing system with a variable speed drive. The pump speed was greatly reduced both when the system was in neutral and during actuation of the cylinders.
The hydraulic system used was located on a production line used for retreating and inspecting strip material, driving actuators and web guiding systems in a 24-hour process.
Normally, when in neutral, power consumption is 9kW. But, under drive control, power consumption was reduced to 2kW. And with the system under load, power consumption was reduced from 22 kW to 12 kW.
With a 16% duty on-load time for the system, the average energy saving over time was 70%. The reduced energy consumption means the payback of the device is 18 months.
Corus' engineers, initially thought it would take the same amount of energy to move a hydraulic cylinder a given distance, regardless of whether a drive or direct-on-line operation is used. However, further tests showed that the drive used a lower motor speed to achieve the required pressure of 90 bar.
