This article presents a several diagnostic methods that can be used to determine the technical condition of electrical machines, especially permanent magnets (PM) machines. Those machines are commonly used in small wind and water systems and vehicles drives. Those methods are preferred by the author in periodic diagnostic of electrical machines. The special attention should be paid for diagnostic methods of turn-toturn insulation and vibrations. Both of those methods were invented in the Institute of Electrical Drives and Machines Komel. Specific structural properties of machines excited by permanent magnets are used in vibration method - electromotive force (EMF) generated due to vibrations. Authors present similarity of machine excited by...