Induction Motor Tradeoff for VSD Driven Pumps and Fans

Abstract

In this paper a new approach in overall drive system choice for centrifugal applications is proposed. This approach lies in tradeoff between number of induction motor poles and overall system efficiency and investment. The proposed technique of induction motor and proper drive selection based on theoretical proof that high nominal speed motor have better efficiency at any operated speed that low speed one in spite of nominal torque is equivalent for both. In present article curves, that represents induction motor efficiency changes versus speed when it driven by VSD, theoretically calculated for various pole number motors at various load types, speeds and VSD control techniques. Based on calculated data energy efficiency and tradeoff analysis for various types of motors and loads was carried out.