TI Automotive saves £24,000 a year on ABB drives 19 September 2012

TI Automotive in Flint, North Wales is reporting savings of £24,000 a year on energy, following installation of ABB variable-speed drives.

Mike Tennant, preventive maintenance engineer for the plant, explains that the plant – which makes 180,000 HDPE (high density polyethylene) fuel tanks a year for global automakers – approached ABB Drives Alliance member Central Group to conduct an energy reduction study.

With production based on blow moulding, the plant uses a lot of compressed air. So Central first installed a 75kW ABB standard drive on the compressor, which had previously been a fixed-speed unit. Running the motor at half speed, the drive immediately reduced consumption from to 45kW, giving a saving of 35%.

Another application was the pumps used for the main factory chilled water circuit, used to cool the mould tools, extruder feed zones and gearboxes, as well as the mould hydraulics and electrical panels.

Installing 11kW ABB standard drives on the three pumps produced a 30% saving, cutting power demand from 11kW to 7kW.

"Both the compressor and the chilled water pumps need to run 24/7," explains Tennant. "As well as the energy savings, we are also gaining production benefits. With the variable-speed drive on the air compressor, we are getting a more consistent air pressure than previously."

And he also says that water pressure is now much more consistent. "With the chilled water pumps, we were finding that, if we had one blow moulder running, we would have high water pressure. But, if we switched in another moulder, the water pressure would drop and require the process to be settled again.

"The variable-speed drive evens out these pressure demands, using a pressure transducer to keep the water pressure in a tight range, meaning production can be started or stopped without upsetting neighbouring production lines."

Tennant also says that the lower controlled pressures have reduced the strain on pipe joints, so reducing maintenance effort. It has prevented the problem of hoses blowing off when moulders where shut down, because spikes are now controlled – meaning seals don't get damaged and hoes don't have to be replaced.

And he adds that the third application to see improvement was the granulator, which chops waste HDPE trimmed from the finished fuel tanks for reuse in the blow moulders.

Also in production 24 hours a day, the granulator only works for 10 seconds of every minute. For the other 50 seconds, the motor was running at full speed.

TI Automotive was doubtful about using a variable-speed drive on this machine. "If the granulator is not run at the correct speed, then chopped material can jam the mechanism, requiring a lot of manual work to get it back to an operational state," explains Tennant.

So Central installed a hire drive on one of the two granulators for a week to prove that it could work. The drive, a 132kW ABB industrial drive, uses its flux optimisation feature to detect the torque demand, ramping the torque up when the machine is chopping material.

Running the granulator motor at the same fixed speed, the drive reduced the motor's power consumption from 42kW to 15kW, a saving of 65".

"This is a huge saving," says Tennant, "and because the payback was only a year on this application, it freed up capital to immediately invest in converting the other granulator to variable-speed control."

Brian Tinham

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