Efficiency is further enhanced with the use of magnetic bearings, which avoid fire friction of rubbing parts associated with traditional oiled bearings. Conventional bearings can use as much as 10,000 w, while magnetic bearings require only 180 w. That amounts to 500 times less friction loss. Current development projects are expanding the range and duty of the compressor wheels and promise to offer even greater efficiency for water-cooled and air-cooled duties and different capacities.CONTROLSThe new compressor effectively is a computer. It provides diagnostic and performance information through Modbus to the refrigeration system, which then communicates to the building automation system through Modbus, LonWorks, or BACnet.CHILLER APPLICATIONThe compressor manufacturer and a major chiller manufacturer teamed up to develop a line of ARI-certified water-cooled chillers, which were expected to be introduced in January 2004. The combination of flooded-evaporator technology and an oil-free system has allowed very close approaches and, subsequently, enhanced performance. The integrated VFD allows excellent part-load performance as power consumption drops off, depending on the head relief, near the cube root of the shaft speed.

"When assessing our supply chain strategy, we realized the need for a cost-effective option such as SPS Commerce''s enablement program to incorporate suppliers into our electronic business processes," stated Todd Wermerson, CIO of Northern Tool. "The streamlined approach will grant us the benefits of reduced order errors and full electronic transactions while improving our vendor order management capabilities."To date approximately 80 percent of suppliers are still using paper and faxes to communicate with corporate buyers, causing a huge bottleneck in the supply chain. SPS'' automated supply chain integration services help streamline the transaction process, replacing current costly and error-laden methods with a hosted model that increases efficiencies and improves order accuracy for enterprises such as Northern Tool. Now suppliers will be able to exchange electronic purchase orders and invoices with Northern Tool, improving delivery times and payments for both parties.

The operation of the feed system is controlled by the patented Vermeer AutoFeed II system, which is designed to monitor and regulate feed rates automatically. The system monitors engine rpm and regulates the amount of hydraulic oil flow to the feed roller motor, based on the engine speed. "It''s an engine-load sensing device," said Brent Bartels, project engineer at Vermeer. "AS wood is fed into the cutting mechanism, that slows the cutter disc down, which loads the engine down so the engine speed is slowing down. If that were to continue, the engine would eventually stall.

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