Technical Report

Assessment of the permanent magnet adjustable-speed coupling system (ASCS)

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  • The purpose of this report is to provide information on the adjustable-speed coupling system (ASCS) including: physical construction, principles of operation, application potential, and laboratory and field test results. In addition, comparison laboratory tests will be presented for conventional adjustable speed drives (ASDs). The ASCS has been tested at three different ratings (50 hp, 100 hp, and 200 hp) driving load profiles representing both fans and pumps. Detailed analyses will be presented for the 100 hp tests, with the summary results including the 50 hp and 200 hp cases as well. The ASCS employs high energy-product neodymium/iron/boron (NeFeB) permanent magnets which act on steel-backed copper discs to provide torque transfer from motor to load without mechanical contact. The slip that occurs between the motor and load shafts can be changed by adjustment of the mechanical clearance of the magnets and the copper discs. Thus, a form of speed control for the load is affected for a system driven by a constant frequency induction motor.
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  • Assessment of the Permanent Magnet Adjustable-Speed Coupling System (ASCS), EPRI, Palo Alto, CA: 2000. TR-
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  • This report was sponsored by EPRI.
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