The medium-voltage variable-speed drive (VSD) for Model YK centrifugal chillers is an addition to the York® OptiSpeed™ VSD line. The drive enables building owners to reduce chiller energy costs as much as 30 percent, when compared to constant-speed operation, claims the manufacturer. The VSD is now applicable on chillers up to 3,000 tons cooling, at voltage levels up to 4,160 volts. The drive's soft start eliminates in-rush spikes at startup and reduces wear and tear on the driveline and other moving parts. Because the soft start also generates less motor heat, chillers controlled by the drive can be restarted in as little as three minutes. The drive incorporates a 24 pulse-converter design with an integral phase-shifting transformer. This technology provides a sinusoidal input-current load to the power grid, eliminating any proliferation of harmonic-current distortion proliferation on the building's power grid that is associated with typical drives, the company claims.

Johnson Controls, Attn: Mike Duguid, P.O. Box 1592-361P, York, PA 17405-1592; 800-861-1001;

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Publication date: 11/27/2006