Induction motors, reciprocating compressors and variable frequency drives

The use of variable frequency drives (VFD) is becoming popular with induction motor driven reciprocating gas compressors. Reciprocating compressors, being rich sources of torque pulsation frequencies, too often create motor component reliability issues. The problem is compounded when variable speed is introduced because of the difficulty in avoiding resonance. This paper reviews key torsional vibration concepts and common motor failure modes. An overview of field testing methods is presented. Also, the unique concerns with variable frequency drives are discussed.