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Reliable HV motors selected for recycling machinery

WEG Electric Motors (UK) Ltdvisit website

 

A 4476kW 12-pole high-voltage motor has been installed in a crusher operated by H Williams and Sons Ltd - and has proven to be utterly reliable in extremely demanding operating conditions.

WEG UK has followed its success in supplying a special 6865kW high-voltage electric motor for what is believed to be the world's largest industrial shredder, at Newport in Wales, with another major recycling order; this time for a 4476kW 12-pole high-voltage machine installed on a new £7million Lynxs shredder owned and operated by recyclers H Williams and Sons Ltd at Hitchin, Hertfordshire.

Richard Emery, WEG MV/HV Product Manager, says: "This order was won on the excellent levels of reliability displayed by the motor supplied to Sims Metal at Newport. The Newport motor has to handle exceptionally heavy thrust loads, which can reach 116 tonnes on the motor drive end bearing; yet despite these operating conditions, it has proved to be 100 per cent reliable."

The Lynxs shredder purchased by H Williams & Sons is the latest design, allowing for improved yield of all metals. It also contributes to the company's ongoing investment in technology to recover non-metallic materials, such as plastics and glass, for recycling. The primary crushing operation is complemented by air separation of heavy and light material fractions, followed by electromagnetic separation of the ferrous and non-ferrous metals. The final stage is the recovery of high-value metals from the waste stream by passing the waste through an induction field.

Within the shredder, the WEG motor drives the hammers that crush scrap at a rate of up to 300 tons per hour. Some 40 per cent of the scrap is end-of-life cars, 40 per cent household items and the remaining 20 per cent is engineering scrap.

Outputs up to 40MW

The 11kV motor is from WEG's M-Line high-voltage range. M-Line motors are designed for larger applications in the output range up to 40MW and voltage range to 13.8kV. They are used widely in demanding oil and gas and power generation applications worldwide, providing outstanding performance and high-efficiency operation. The M-Line motor on the Hitchin shredder has fabricated steel ribbed bearing housings for added strength. It is also equipped with a forged shaft, and both of its main bearings are electrically insulated to ensure long-term reliability.

Such is the power consumption of the motor that it has its own 33kV supply from a sub-station and is connected to an auto transformer. It provides the drive for the shredder hammers via a fluid coupling. The motor is started with the primary and secondary halves of the coupling disconnected; but when it reaches required speed, oil is pumped progressively into the secondary half of the coupling, connecting the two halves and providing an effective soft start for the motor operation. The fluid coupling also provides protection in the event of the shredder jamming; in such instances it will slip providing, in effect, a clutch mechanism that safeguards the motor.

George Bond, head of operations for metal and waste recycling at H Williams & Sons, comments: "We know the people at Sims Metal and we respect their opinion, so when we asked them about using a WEG motor on our new shredder, we had no hesitation in taking their advice. We have not regretted that decision; the WEG motor has operated with total reliability, running ten hours a day, five days a week, since we commissioned it just over nine months ago in July 2006."

Richard Emery adds: "The H Williams application is further endorsement of the performance and reliability of our high-voltage motors in the most demanding of applications. Other companies have taken note of this, and the result is a high level of large machine business for WEG."

About H Williams and Sons Ltd

H Williams and Sons Ltd is part of Metal and Waste Recycling, one of the biggest recyclers of ferrous and non-ferrous metals in the UK. The organisation offers in-depth expertise in all fields of metal recovery.

The Hitchin site is capable of processing 600,000 tonnes of ferrous material per year using state-of-the-art technology to maximise recovery. The investment in modern plant reflects the company's commitment to continually improve the service range offered to its ever-increasing client base.

05 July 2007

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