Approximate Method For Calculating Current Pulsations Caused By Induction Motors Driving Reciprocating Compressors
Induction motors driving reciprocating compressors experience fluctuating electromagnetic torques at the rotor, which in turn cause current pulsations in the stator windings. We present an approximate method for calculating these current pulsations based on estimates of the fluctuating electromagnetic torques, and on basic electrical information about the motor that is readily available early in a design project. The electromagnetic torque fluctuation estimates are derived using a method developed for torsional vibration analysis presented at GMRC 2013, and further confirmed by field measurements. The present work of predicting current pulsations is intended to give the designer an approximate, but conservative, method to evaluate current pulsations against the 40% limit for induction motors specified in API 618.