WELSH steel manufacturer Corus, based in Deeside, has retrofitted its existing hydraulic systems with ABB variable speed drives, which, it claims, has lead to significant energy savings.
ABB says hydraulic systems typically waste energy by continuously circulating fluid, even though they only carry out work in short bursts. Furthermore, hydraulic system pressure is normally maintained by a positive displacement pump, which can not save as much energy as the more common centrifugal pump.
The hydraulic system used by Corus was located on a production line used for retreating and inspecting strip material. It continuously drove the actuators and web-guiding systems in a 24 hour process.
Normally, the power consumption in a neutral state is nine kilowatts. However, this was to two kilowatts with the ABB variable speed drive. Similarly, the system’s power consumption when carrying out work was reduced from 22 to 12kW.
According to ABB, with a 16% duty on-load time for the system, the average energy saving over time was 70%. This reduced energy consumption, means the variable speed drive will pay for itself within 18 months.
ABB says the engineers at Corus 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 was used. However, tests showed that the variable speed drive used a lower motor speed to achieve the required pressure of 90 bar.
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