2006-05-08 - Severn Trent Water, the world’s fourth largest privately owned water company, achieved a 65 percent energy saving with ABB drives at a U.K. wastewater treatment plant.
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So great were the benefits of the three ABB standard drives that the customer set up an Energy Saving Project Group to look at replacing and upgrading existing drives throughout its network of 1,000 wastewater treatment plants in the U.K.
The catalyst to the project was a one-day ABB training seminar on the advantages for water utilities of upgrading or replacing their existing drives. Severn Trent’s Dan Hulse, an instrument and electrical engineer, attended the seminar.
An eye-opener
“The day opened our eyes to the real benefits of using variable speed drives,” says Hulse. “We could see that our investment would be rewarded virtually immediately, and this has proved to be the case.”
ABB is the market and technology leader in motors and drives worldwide. As a result of the seminar, Severn Trent invited ABB to one of its wastewater treatment works to log the power consumption of various applications like aerators, tertiary pumps and water pumps.
“We have lots of different pumps – centrifugal, screw and dry weather pumps – all doing different jobs and with variable heads and different loading. AC drives can help enormously in all these applications,” says Hulse.
Payback in seven months
The first installation of ABB drives replaced three 20-year-old drives on water process pumps and achieved a saving in power consumption of 65 percent, equivalent to a payback time of seven months and a total saving of $80,000 over the five years of the ABB warranty.
Additional benefits that the customer discovered (but had not expected) were a significant reduction in noise levels, less wear on the pumps, smaller footprint, simpler control wiring, and less heat generation.
A second installation of ABB variable speed drives on two aerators reduced power consumption from 90 kWh to 70 kWh, equivalent to a payback time of 11 months and a saving of $50,000 over the warranty period. And a third installation of six ABB standard drives improved process quality, eliminated power spikes and significantly reduced wear and tear on vulnerable, one-meter-diameter valves.
Severn Trent Water recently renewed a three-year service contract with ABB for the repair and maintenance of 60,000 low-voltage AC motors at some 5,000 sites in the U.K.
“This organization [ABB] has completely revolutionized the way motors are supplied, installed and maintained,” said Jeremy Jones, area maintenance manager at Severn Trent.
Read more about the results of each installation and the customer’s assessment of the project to reduce power consumption at its wastewater treatment plants.