Understanding Frequency Response of Induction Motor Winding through Electromagnetic Wave Equations

Abstract

Frequency response analysis offers an in- sight about the integrity of machine windings, when employed as a tool for condition monitoring. To en- sure that, an electromagnetic wave is injected from one terminal of winding, and the power of the wave at the receiving terminal is measured. The power at the termi- nals is measured in terms of either voltage or current. This difference in power at the two terminals can be at- tributed to the medium’s permittivity, permeability and conductivity, through which the signal is being trans- mitted. This paper offers an explanation for the behav- ior of the voltage gain frequency response of induction motor winding and propagating medium parameters by employing the fundamental electromagnetic wave equa- tions. Their explanation illustrates how these param- eters can affect the response. The correlation estab- lished using Maxwell’s equation and these parameters with frequency response analysis is evident while iden- tifying open winding fault and issue with machine core inductance. The results are analyzed and interpreted with the new correlation.