Fibre optic monitoring of induction machine frame strain as a diagnostic tool

This paper investigates the application of Fibre Bragg sensing for monitoring of induction machine frame strain. The underlying purpose is to examine the feasibility of frame surface attached fibre optic sensing to be used for condition monitoring purposes, i.e. for recognition of signatures characteristic of healthy and/or faulty machine operating conditions. To this end an experimental study is reported that compares the fibre optic monitored circumferential strain signal spectral content with that of synchronously monitored frame acceleration and shaft torque signals on a laboratory induction machine operating with and without electrical fault. It is shown that the signature of electrical unbalance and fault, as well as that of mechanical effects on the shaft can be effectively recognised in the frame strain signal monitored by the fibre optic strain sensor.