Detection and location of interturn short circuits in the stator windings of operating motors

Abstract

Motors are critical components for electric utilities and process industries. A motor failure can result in the shutdown of a generating unit or production line, or require that redundant plant be utilized to circumvent the problem. One major cause of failures is breakdown of the tum insulation leading to puncture of the groundwall. Early detection of intertum shorts during motor operation would eliminate consequential damage to adjacent coils and the stator core reducing repair costs and motor outage time. In addition to the benefits gained from early detection of tum insulation breakdown, signijicant advantages would accrue by locating the faulted coil within the stator winding. Fault location would not only increase the speed of the repair, but would also permit more optimal scheduling of the repair outage. This work was successful in practically implementing a theory to predict changes in the axial kakage flux resulting from stator winding intertum shorts and in developing an algorithm to locate the position of the faulted coil. An experimental setup consisting of a 200 hp motor loaded by a generator was used to validate this theory. Suitable transducers were developed and installed on this motor. Measurement using this experimental configuration clearly validated the theoretical model. On the basis of this experimental work, an instrument to continuously monitor for shorted turns is under development.

Stator winding fault diagnosis in synchronous generators for wind turbine applications

“…Unless detected early enough, it might lead to fire, explosion, and even loss of personnel [8]. It has been reported that a turn to turn short circuit results in a disruption of the magnetic field symmetry in the winding region of the machine as well as increasing the magnitudes of certain harmonic components [9]. Turn-to-turn faults are difficult to detect with confidence.…”

“…According to [9], the occurrence of a turn-to-turn fault results in a disruption of magnetic field symmetry in the end winding region of the machine as well as increasing the magnitudes of certain harmonic components. This is because there is a severe imbalance between the current flowing in the shorted turn and the corresponding diametrically opposite turn in the winding.…”

Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

“…However, methods based on axial flux have two drawbacks that can weaken monitoring efficiency [19]. First, multiple probes with high concentricity must be installed at the end of the winding coil.…”

“…4) Methods based on axial flux Faults can be detected through shaft voltage and axial magnetic flux leakage [19][20][21]. However, methods based on axial flux have two drawbacks that can weaken monitoring efficiency [19].…”

“…Axial magnetic flux leakage [19][20][21] Monitoring of inter-turn short-circuit fault as well as phase-to-phase and phase-to-ground insulation deterioration Installation of multiple probes with high concentricity is required Vibration signal analysis [22][23][24] Monitoring of inter-turn short-circuit fault and winding insulation deterioration…”