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C. Zöller, M. Vogelsberger, R. Fasching, W. Grubelnik, T. Wolbank:
"Evaluation and Current-Response-Based Identification of Insulation Degradation for High Utilized Electrical Machines in Railway Application";
IEEE Transactions on Industry Applications, 53 (2017), 3; 2679 - 2689.

The demand for condition monitoring systems to prevent
a breakdown of electricalmachines is continuously increasing.
A failure or collapse of the insulation is one of the main reasons
for a machine outage, both in the field of high-voltage machines as
well as low voltage. Especially at inverter-fedmotors, several kinds
of stresses due to parasitic phenomena exist and cause decrease of
the insulation lifetime. With the method proposed, the evaluation
of the stator insulation health condition of inverter-fed motors is
possible by analyzing the current sensors transient response after
inverter voltage step excitation. The analysis of the transient signal
portion gives evidence of a possible change in the insulation system
by comparison of the characteristics with the known pattern of the
healthy machine transient signal portion. Tests are performed on
a 1.4-MW induction machine designed for traction applications.
By the availability of taps accessible on the machine terminal, different
scenarios to emulate winding insulation degradation are
conducted. Additionally, in order to investigate insulation degradation
characteristics of the used insulation materials, accelerated
aging procedures are applied on specially manufactured stator slot
models with form-wound coils. These stator test segments have
been aged by different accelerated aging cycles until the failure of
the insulation is determined by voltage exposure tests. With additional
nondestructive diagnostic measurements, e.g., dissipation
factor (tan δ), capacitance, the correlation between these indicator
values, the results of the proposed method, and the degradation
of the insulation strength until a breakdown are investigated.

Aging, fault diagnosis, induction motors, insulation

http://dx.doi.org/10.1109/TIA.2017.2661718

http://publik.tuwien.ac.at/files/publik_267248.pdf