When the drive on the hammer mill at environCom’s e-waste recycling plant in Grantham failed and a solution was needed quickly and cost-effectively, the operator turned to Ralspeed for help

At environCom’s e-waste recycling plant in Grantham, up to 100,000 tonnes of waste electrical and electronic equipment (WEEE) can be reprocessed per year. A key element of the plant is the hammer mill, which is used to break down almost all of the waste, ranging from washing machines and electric toasters to televisions and computers.

Just before Christmas in 2011, however, the 335kW AC variable speed drive for the hammer mill failed. The mill being out of service resulted in serious disruption to the operations.

Having contacted several potential suppliers in an effort to find one that could help with remedying the problem quickly and cost-effectively, the company selected Ralspeed as the company quoted the best price and fastest delivery time. It was also confident that Ralspeed could effectively address the underlying problems that had caused the failure, explains David Baldwin, head of engineering.

Engineers at Ralspeed inspected the failed drive system and discovered that the principal reason for failure was that all of the ventilation channels in the drive power sections had become blocked by the dust produced during the operation of the hammer mill. This had led to the overheating and failure of two converter modules, putting the existing drive beyond economic repair.

The solution proposed was to supply a replacement panel with a new Vacon NXC series modular AC variable speed drive. Initially, consideration was given to siting this new panel in a location further away from the mill itself, where it would be exposed to far less dust. Further investigation showed, however, that this would be expensive, not least because of the high cost of extending the 400mm2 three-phase copper cables used to supply power to the panel.

The company therefore took the alternative approach of arranging for the panel to be vented to clean outside air via ducting.

Drive benefits

Ralspeed quickly sourced the new drive from Vacon UK, and then completed and tested the new panel, delivering it to the site early in January. Installation and commissioning was then quickly completed, and the hammer mill was back in full operation less than three weeks after the failure occurred.

Of additional benefit to the company, tests carried out on the new control panel showed that the power section of the drive was now running at a temperature of less than 20°C, allowing a very wide safety margin to cater for even the highest ambient temperatures likely to be encountered on the site.

Baldwin added: “Throughout this whole project, we had outstanding support from Ralspeed, and we were very impressed by the company’s ability to react quickly at what is, for any business, one of the most difficult times of the year.”


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