Analysis and detection of shorted turns in the field winding of cylindrical roter synchronous machines

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Due to the continuous use of large generators jn induRtry and in power stat.ions, and the need to keep such machines running reliabJy, the detection of shortpd field winding turns in synchronous machines is of increasing importance. The most serious outcome of a dpteriorating fault condjtjon is .increased vibration, and on-line monitoring to detect winding(and other) faults in the largest machines is nowa strong possibility, and certainly periodic monitoring of alI large machines in strategjc sjtuatjons. The principal aim of this thesis is to devise a analytical model to detect the appearance of short-ciruit, the field coil concerned and the number of turns involved. To achjeve this objective, the analytjcal and experimental technique considered is to use two matched diagonally opposite air-gap search coils connected jn a way that exposes the "difference" field of the fault. The predicted results are verified bi open-circujt measurements on a small four-pole model machine in which faults can be established. rotor two-dimensional a rotor known rotor Throughout this thesis, some other faults whjch occur in the machine, possibly wholely or partly due to the presence of a rotor short-circuit itself, are considered jn detajl; such faults as unbalanced magnetic pull(ump), static and dynamic eccentricity. In order to take full by saturation and the two,-dimengional account of the nonlinearjty, caused presence of Rlotting analysig uRing ljnear tr.ianguJar fjnjtp elements is also presented. Computations were pertormed under no-load and Joad conditionR.