Overview

This standard provides guidance for the measurement of dielectric loss factor on stator bars or coils with preformed elements and complete windings. The dielectric dissipation factor is a measure for the dielectric losses in the stator winding insulation. The measurement of this dielectric dissipation factor is an appropriate means of assessing the quality of new but also aged stator winding insulation of rotating electrical machines, especially of assessing the uniform quality of manufacturing and the dielectric behavior of the insulation as a whole. At aged stator windings the dielectric dissipation factor provides information on the condition of the insulation. The dielectric dissipation factor measurements give no indication of the distribution of loss within the insulation and - in contrast to the off line PD-measurement - it is not possible to locate weak points in the insulation system. The characteristic principle is the measurement of the loss factor in a certain voltage range and the derivation of various characteristic parameters for the dielectric losses as a basis for the evaluation. Empirically determined limit values confirmed in practice can be used to evaluate the manufacturing quality of stator winding insulation. Furthermore, trend evaluations, for example in the context of diagnostic tests as part of a functional evaluation of the insulation systems or during maintenance and overhaul of rotating machinery, can provide information on the aging process, necessary further measures and for scheduling overhauls. However, the actual time to stator winding insulation failure cannot be determined from such trend assessments. The responsible committee is DKE/K 311 "Drehende elektrische Maschinen" ("Rotating electrical machines") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.

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Responsible national committee

DKE/K 311 - Drehende elektrische Maschinen