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Case Studies - Variable Frequency Drives

ABB energy appraisal saves $17,000 for cooker plant

General Domestic Appliances Ltd, at its manufacturing plant in Stoke on Trent in Staffordshire, manufactures 12,000 cooking products a week for its market leading Creda, Hotpoint and Cannon brands. As part of a continuous programme to improve quality and energy efficiency at the factory, the company decided to look at the energy consumption of its wet fume extraction plant, which extracts waste vitreous enamel from four paint booths. Some of the booths were not in constant use and were closed off by a mechanical shutter, yet the 132kW fan used to extract the waste enamel was run at a constant speed, wasting energy and money.

Plant engineer Andy Rowe, asked Glen Hickman of ABB Drives Alliance partner Central Electrical, to carry out an energy appraisal on the plant, with a view to cutting energy consumption.

Central Electrical’s calculations showed that the speed of the fan could be reduced by 20 percent, resulting in a 56 percent reduction in power from 118kW to 51kW, saving over 440,000 kWhrs a year.

Central Electrical recommended an ABB ACS 600 AC drive, supplying and commissioning the equipment. The appraisal was repeated after the drive was commissioned to confirm the estimated savings figures. Andy Rowe says: “Central Electrical estimated we would save approximately $16,000 on the energy bill for the wet extraction plant in the first year. In fact we saved $17,000 and achieved a payback period of only four months.”

This type of energy appraisal is the cornerstone of ABB’s new six-step energy plan, designed to help companies save energy in preparation for the introduction of the Climate Change Levy.

ABB Drives Alliance members collect and analyse data from the customer’s site using dedicated software and prepare an Executive Summary and a detailed Engineer’s Report. They also help implement the recommendations and train staff at the client company to continue the process. The appraisal process can involve effective motor management schemes to maximise savings, as well as replacing older, less efficient drives with new, more advanced drive technology such ABB’s DTC.

Says Glen Hickman: “The energy consumption over a typical week was assessed with an energy monitor. Then, using a software package that analyses fan operations and energy use, we were able to calculate a speed reduction that would save energy while still maintaining the required sufficient extraction from the plant.”

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