Electrical Aging of the Insulation of Low-Voltage Machines: Model Definition and Test With the Design of Experiments

Abstract

The aim of this paper is to present a method for modeling the lifespan of insulation materials in a partial discharge regime. Based on the design of experiments, it has many advantages: it reduces the number of time-consuming experiments, increases the accuracy of the results and allows lifespan modeling under various stress conditions including coupling effects between the factors. Accelerated aging tests are carried out to determine the lifespan of these materials. The resulting model presents an original relationship between the logarithm of the insulation lifespan and that of electrically applied stress and an exponential form of the temperature. Results show that the most influential factors can be identified according to their effects on the insulation lifespan. Moreover, the lifespan model validity is tested either with additional points which have not been used for modeling or through statistical tests. Finally, it is shown that fractional plans are not suitable to r e d u c e t h e n u m b e r o f e x p e r i m e n t s. T h i s a p p l i c a t i o n o f t h e experimental design is best used during the initial phase, before the final drive has been built and any on-line diagnostic.

Investigation of equivalent stator-winding thermal resistance during insulation system ageing

“…During the life cycle of the winding, these materials age, degrading the properties of the insulation and ultimately leading to failure. There have been a number of studies attempting to model this anticipated insulation life, based on thermal [10] [11], electrical [12] and multi-stress scenarios [13][14][15][16]. Standards have developed to allow designers to understand the temperature constraints and life of materials [17] [18].…”

The Impact of Thermal Degradation on Properties of Electrical Machine Winding Insulation Material

“…Additionally, it was found in [23] that after the initial ageing cycles, there was a shift of the dissipation factor and the capacitance at all voltage levels towards lower losses and capacitances because of the drying out and post curing of the insulation. Moreover, a new life span model was developed in [24], which presents an original relationship between the insulation life span and the stress parameters with the application of the Design of Experiments (DoE) methodology. Also, in [25] a new cable monitoring method was proposed based on impedance spectrum analysis in the high frequency range.…”

The impact of thermal degradation on electrical machine winding insulation

“…Additionally, it was found in [22] that after the initial ageing cycles, there was a shift of the dissipation factor and the capacitance at all voltage levels towards lower losses and capacitances because of the drying out and post curing of the insulation. Moreover, a new life span model was developed in [23], which presents an original relationship between the insulation life span and the stress parameters with the application of the Design of Experiments (DoE) methodology. Also, in [24] a new cable monitoring method was proposed based on impedance spectrum analysis in the high frequency range.…”