Contactless energy transfer: Mobile power on the go

Many plant engineers or production system designers can tell you that electrical wiring is the bane of their existence. From installing the wires to rewiring as production lines need to be changed to repairing damaged cables and connections, electrical wiring represents an ongoing cost and risk for downtime in manufacturing plants.

01/01/2007


Many plant engineers or production system designers can tell you that electrical wiring is the bane of their existence. From installing the wires to rewiring as production lines need to be changed to repairing damaged cables and connections, electrical wiring represents an ongoing cost and risk for downtime in manufacturing plants.

Until recently, the miles of electrical wiring that snake around any manufacturing facility, hanging down from ceilings and extending across corridors between equipment, have been viewed as a necessary aspect of industrial automation.

But industry is moving toward a wireless world. Like consumers with their cell phones, laptops and Blackberry devices, industrial companies want wireless technologies that improve versatility, reduce costs and maintain connectivity. One of the latest developments to draw interest among engineers is contactless energy transfer for powering and controlling motors.

While wireless communication is now common in factories, wirelessly transferring 16 kW of electricity through the air to power equipment is a relatively new phenomenon in the U.S.

With contactless energy transfer, a non-contact radio frequency system transfers electrical energy inductively from an insulated conductor in a fixed installation to one or more mobile loads. Electromagnetic coupling is accomplished via an air gap, so it is not subject to wear and costly maintenance. For example, in some automated manufacturing facilities, automatic carts full of parts must be moved between the different stages of a production process.

Contactless energy transfer can be used overhead in storage-and-retrieval systems or underground for material handling systems. The technology reduces costs by eliminating festooning or overhanging utilities. Underground wiring is compact and poses no trip hazards. There is no carriage to run out on the shop floor. There are also no pits to be dug to drop in trailing utilities.

A mobile system using contactless energy transfer provides greater versatility: The contactless system enables more flexible track layout with curves and switches, simple segmentation of tracks, which makes it easy to extend a track or change travel directions, and higher speeds.

Contactless energy transfer is ideal for applications where:

  • The mobile equipment must cover long distances

  • A variable, extendable track layout is required

  • High speeds must be achieved

  • The energy transfer must be maintenance free

  • Additional environmental contaminants are not permitted in sensitive areas

  • The operation takes place in wet and humid areas.

    • Maintenance and ambient conditions are important factors in constructing systems for material handling and transportation applications, such as automotive assembly, storage-and-retrieval logistics and sorting. Typical applications that could benefit from contactless energy transfer include:

      • Overhead trolleys

      • Conveyor trolleys

      • Guided floor conveyors

      • Push-skid conveyors

      • Storage-and-retrieval units

      • Pallet transportation systems

      • Panel gantries

      • Elevator equipment

      • Battery charging stations.

        • By replacing a drag-chain system in a conveyor trolley that transports and sorts pallets, for example, contactless energy transfer enables pallets to transverse longer distances. Complicated holders for drag chains are eliminated, as is downtime for repairing cable breaks and battery charging. Repairs for wear from bending or torsion are also eliminated.

          The wear-free power supply in a contactless system has many advantages in designing and maintaining push-skid conveyors used in automotive assembly, for example, or in storage-and-retrieval units in high-bay warehouses. Because there is no conductor rail, there is no danger of introducing contaminants from system leakages and no components that are difficult to reach for maintenance. Problems with fitting platforms into conveyor belts are also eliminated, since there’s no need for tight mechanical tolerances between the line cable and pick-up.

          Perhaps the biggest advantage of a system based on contactless energy transfer is higher system availability, because the system is essentially maintenance free. In a manufacturing environment where change is a constant and speed is an imperative, the versatility, flexibility and reliability of contactless energy transfer systems can reduce the wear-and-tear on plant engineers as well as equipment.


          <table ID = 'id3003156-0-table' CELLSPACING = '0' CELLPADDING = '2' WIDTH = '100%' BORDER = '0'><tbody ID = 'id3008408-0-tbody'><tr ID = 'id3002358-0-tr'><td ID = 'id3001870-0-td' CLASS = 'table' STYLE = 'background-color: #EEEEEE'> Author Information </td></tr><tr ID = 'id3002364-3-tr'><td ID = 'id3001652-3-td' CLASS = 'table'> Rainer Neufeld is a graduate of the University of Applied Sciences, Mannheim, Germany, where he received a degree in electrical engineering. He joined SEW-EURODRIVE in 1999 as an application engineer, first in Germany and since 2004 in the United States. He is also product manager for SEW’s Movitrans contactless energy transfer systems. </td></tr></tbody></table>


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