The Trane Company (La Crosse, WI) has expanded its offering of retrofit adaptive-frequency drives (afd) for existing chillers to include a 1,000-hp model. The drives are designed to help oversized chillers run at low load to conserve energy and assist in quieter operation of the chiller, according to the manufacturer. Typical applications are facilities that operate 24/7 at part-load conditions. Other water-cooled afd's are available in 350-, 450-, and 650-hp models.