Drive saves £14,000 in a year

Paul Boughton
Energy costs for the operation of a 90kW rotary compressor installed at Albion Automotive, one of the UK’s automotive tier 1 suppliers, have fallen by £14,000 per year after compressor experts, Glaston Compressor Services, fitted a Vacon NXS variable speed drive controller.

The drive, which replaces the existing single-speed starter, works in conjunction with a compressor management system developed by Glaston.  This is arranged to ensure that the output of the compressor always matches the instantaneous demand for compressed air.

Glaston has been responsible for supplying and maintaining energy efficient HPC compressors at the Albion Automotive site since 1996 and, on the basis of its experience elsewhere, the company knew that fitting a Vacon variable speed drive would yield substantial energy savings.

“We’ve been using Vacon drives for some time to upgrade fixed-speed compressor systems, and we’ve found them to be robust, reliable and easy to work with,” said Michael Douglas, Managing Director of Glaston Compressor Services.

“We’ve also found that we can always rely on superb support from Vacon, with direct access to the company’s top people.

In order to quantify the savings that would be made possible by fitting the Vacon drive, and to make a compelling business case for Albion Automotive to invest in the upgrade, a free detailed energy survey was carried out at the site. The findings initially indicated that the new drive would provide savings of £7,000 per year, against a total cost for the project of around £12,000.

With the prospect of payback in less than two years, Albion Automotive decided to proceed. The installation went smoothly, with minimal disruption to the operation of the compressor installation.

“Glaston did a lot of preparatory work so that all that remained to be done on site was a small amount of wiring,” said Tony Stableford, Maintenance Facilitator at Albion Automotive. “Once this wiring had been completed, the compressor was up and running in less than half an hour.”

“The Glaston engineers then spent another couple of hours using the full range of facilities offered by the Vacon drive to fine tune the installation so that it would maximise our energy savings.”

In addition to the anticipated energy savings resulting from continuously matching the operating speed of the compressor to the instantaneous load, it also proved possible to make further savings by reducing the nominal operating pressure of the installation.

The minimum acceptable delivery pressure for the production plant at Albion Automotive is 6bar. In the past, the installation has been operated at a nominal pressure of 7.0 to 7.5bar to ensure that, even under conditions of maximum peak demand, the delivery pressure never fell below the required minimum.

With the much more precise and responsive control achieved by the Vacon drive system, the nominal delivery pressure can now be reduced to just 6.05bar, with total confidence that the actual pressure in the installation will never fall below the 6bar limit.

As a result of this reduction, and a number of other minor energy saving adaptations made by Glaston, the total cost savings increased from the forecast £7,000 to £14,000 per year.

“Payback in 14 months is within the company set financial hurdles,” said Tony Stableford. “Our only regret is that we didn’t make the change to variable speed operation for the compressor sooner.”

“From our point of view, the project was completed smoothly and quickly with almost no disruption to our operations, and now it’s not only contributing to cost savings, it’s also helping us to reduce the environmental impact of our operations. However you look at it, that’s a great result!”

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