Adjustable Speed Drives 2 : An electrical device or group of electrical devices that alters the drive motor output speed over a range in a controlled manner
NFPA 79 Electrical Standard for Industrial Machinery, 2002 ed. http://www.nfpa.org/assets/files/AboutTheCodes/79/ 79-A2002-rop.pdf, (Electr Std for Ind Machinery - Amer) {225 NFC}