Using low noise induction magnetometer for online monitoring of the induction machine

This paper presents a design of the low noise induction magnetometer (IM) to measure the stray magnetic field for online monitoring of the induction machine. The frequency response and noise model of the IM are analyzed. An optimal IM is designed and developed, with the linear frequency response from 1Hz to 10kHz, which makes the IM be capable of time-domain and frequency-domain applications. The noise level of the IM is 2pT/VHz at 10Hz, 0.7fT/VHz at 20kHz. The magnetic fields during the safe and fault conditions of the induction generator are tested. The measurement results confirm that the low noise IM is efficient for online monitoring of the induction machine.