Design, fabrication, back-to-back test of 14200-hp two-pole cylindrical-rotor synchronous motor for ASD application

This paper describes the design aspects, fabrication, and testing of a 14200-hp two-pole cylindrical-rotor synchronous motor used with a load-commutated inverter (LCI) adjustable-speed drive (ASD) to drive a refrigeration compressor for a refinery alkylation plant. The motor design aspects include extensive finite-difference analysis of the rotor cage assembly and laboratory bench testing of a wedge assembly to verify finite-difference analysis results prior to fabrication. Torsional and harmonic analysis results are also presented. Special considerations are discussed regarding rotor heating due to harmonic currents and mitigation methods for handling the harmonic currents and heating. Mechanical design aspects are presented of the rotor cage, including rotor slot design, wedge, and end ring assembly. Two motors and drives were built, for companion projects, allowing for verification of the rotor-cage assembly by a back-to-back (BTB) test. Test preparation, setup and results are presented, including rotor temperature mapping, vibration data and torsional results. Finally, test results are compared with calculated values.