INDUCTION MOTOR CONDITION MONITORING: SLIP FREQUENCY AND POLE PASS FREQUENCY - A CLARIFICATION OF DEFINITIONS

摘要

Vibration Analysis and Motor Current Signature Analysis (MCSA) are the condition monitoring techniques widely used in modern industry to diagnose problems in three-phase induction motors. Correctness in the use of fundamental terms of the induction motor theory is key in avoiding misunderstanding and possible confusion between specialists using these techniques.rnThe aim of this presentation is to show the relationship between the Slip Frequency and Pole Pass Frequency based on the original definition of Slip Frequency from the classical theory of induction motors. A historical overview of the usage of the slip frequency and pole pass frequency in the practical induction motor condition monitoring also is presented. The conceptual distinction between the classical slip frequency and conventional slip speed is emphasized. The presentation gives preference to the 'twice slip frequency' terminology in vibration analysis, which is in line with the classical theory of induction motors and has a clear meaning of the physical processes within the motor. Returning to the classical 'twice slip frequency' in induction-motor vibration-analysis training programs is a reasonable step which will promote the terminology convergence of different condition monitoring techniques and which will encourage a common language by all specialists working in the field of induction motor analysis.