Developing a special method for maintenance of electrical equipments of industrial company is necessary for improving maintenance quality and reducing operating costs. Critical equipments of industrial company require the combination of correct preventative and condition based maintenance. This type of maintenance policy and strategy will improve performance of these equipments through availability of industrial equipments. Many vibration environments are not related to a specific driving frequency and may have input from multiple sources which may not be harmoniously related. Examples may be excite from turbulent flow as in air flow over a wing or past a car body, or acoustic input from jet engine exhaust, wheels running over a road, etc. For these types of vibration, it would be more accurate, or more interest to analyze and test them using random vibration. In this research we have calculated RMS and PSD (Power Spectral Density) of electromotor fan in different faults situations. We have calculated Grms and PSD for different faults. The results showed that different faults were showed different PSD vs. frequency. The results showed that with calculating PSD we could find some fault and diagnosis of electromotor as soon as possible.
