Experimental method for synthesis of generalized thermal circuit of polyphase induction motors

A new method for determining the equivalent parameters of a generalized the rmal model of induction motors (IM) based on the no-load testing of IM is p resented The representation of the full thermal network of IM is reduced to a system of only three simultaneous equations. By solving these equations three equivalent thermal parameters of the generalized thermal model are ob tained. The calculation is based on accurate measurements of the temperatur e rise in stator windings and the power absorbed by the tested motor. The t hermal tests are done in the no-load running of IM (one test is like an ope n-circuit test and the other two are like short-circuit tests). Hence these methods of testing may be carried out without expensive equipment and thei r power consumption does not exceed the losses, which occur under full load conditions. With the help of this thermal model the final temperature rise at the full load run according to rated losses, can be easily estimated Th ree totally enclosed IM were tested by these methods and the difference in the predicted and measured temperature rise of the stator winding was withi n 2-3 degreesC.