VSDs slash pump energy consumption for aquarium

The installation of ABB variable-speed drives to control pumps at the National Marine Aquarium in Plymouth is reducing electricity bills by over £15 000 a year. A saving of £2900 a year is being achieved with one 11 kW pump alone. Nine variable-speed drives have replaced programmable logic controllers and control of flow and pressure by manual throttle valves — resulting in excessive energy consumption as the pumps always ran at full speed. The new installation uses pressure transducers in the pump output to provide a feedback signal to the drive to vary speed to provide the desired flow rate. Duty and standby pump sets are controlled by a single drive, changing over automatically as required. The aquarium has a seawater tank holding 2.5 Ml. Keeping the fish healthy involves constant pumping of water at the correct temperature. John Selwood, engineering manager for the aquarium, says, ‘We needed to save energy. However, we have nine pumps for the tanks that must be on all the time, with varying flow and pressure.’ The requirement for constant operation meant that the installation of the drives had to be achieved with minimum downtime. Andrew Botterill, managing director of electrical contractor Drew & Co., explains, ‘We programmed one drive and tested it in the workshop. Then all we had to do was to plug that drive’s keypad to the other drives and upload the parameters. The interchangeability of the keypads was the key to installing the drives quickly. We installed each drive in only two hours.’
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