Frequency-Amplitude Analysis
A typical stator phase current plot for the healthy motor operating at 100% load is shown in Fig. 2. The rated current for the motor is close to 10 Ampere. The frequency analysis and the time-frequency analysis methods have also been estimated for all the experimental data. The frequency resolution was kept 1.25Hz with 90% overlap and number of average 82 for all the signal processing. The computation time using the Pentium-IV PC for both frequency and time-frequency analysis was less than 25 sec which is definitely quick process for the health monitoring purpose. Firstly, the EDFT is plotted easily on frequency domain (as seen in Fig. 2-B). The first harmonic can be seen 50 Hz (main frequency) and followed by 150 Hz (generally used for stator fault detection). The harmonics at frequency 25 Hz and 75 Hz is sideband (generally used for rotor fault detection)