Replacing DC drive with ABB AC drive & motor saves £50k p.a
Replacing a 400kW DC motor with an ABB 4 pole squirrel cage motor and AC variable-speed drive has saved a plastic recycling company £50k p.a.
Regain Polymers of Castleford, West Yorkshire, is one of the largest plastic recycling companies in the UK, recycling around 50,000 tonnes a year. The company turns waste plastic materials such as polypropylene, high density polyethylene and polystyrene into new pellets that are used to produce products such as water pipes and wheelie bins.
Production is based on seven extruder lines, and as part of its programme to cut energy use and carbon emissions. Regain identified one of its extruder lines as a candidate for improvement. This was based on a 400 kW DC motor and the company wanted to convert it to AC operation.
Saving 488 tonnes of CO2 a year
A 400 kW ABB AC 4 pole squirrel cage motor and variable-speed drive, together with new mains cable were installed. Following installation, the energy costs dropped by nearly 40% from £420 to £260 a day based on a 24 hour a day production. Allowing for 300 total production days a year, this gives Regain Polymers an energy reduction of nearly 870,000 kWh per year, and provides a total annual saving of £49,000 p.a. In addition, it is estimated this will save over 488 tonnes of CO2 p.a.
The AC motor runs at the same speed as the previous DC motor, with savings coming from the improved torque ratio and efficiency of the AC drive and motor. As well as the expected energy savings, the conversion to AC would eliminate the need to replace the DC brushes every three months, saving £2,500 a year.
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