Experience with accelerated aging tests on stator bars and coils

Stone, G.C.; Gupta, B. K.; Lyles, J.F.; Sedding, H.G.

doi:10.1109/elinsl.1990.109772

Cited by 23 publications

(10 citation statements)

References 6 publications

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“…influences the potential insulation life L. Loss factor and partial discharge measurements during thermal cycling tests [8,14,16,17] on high voltage winding insulations confirm the formation of delaminations between the strand and the groundwall insulation ( Figure 1) which is also observed in rotating machinery [1,7]. However, there are insulation systems for which both breakdown voltages and voltage endurance are not reduced even after several hundred temperature cycles.…”

Section: Introductionmentioning

confidence: 91%

Retardation of electrical tree propagation by resin degradation

Weiers¹,

Keller²,

Hutter

et al. 2006

Int Trans Elec Energy Syst

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SUMMARYIn order to improve insight into the effect of delaminations between the conductor and the groundwall insulation on the ageing of high voltage rotating machinery insulation, the influence of the polymer degradation on tree growth has been studied. Simultaneous partial discharge measurements and photograhic observations have been conducted in order to investigate the effect of the degradation of the resin on electrical tree propagation. The photographic observation indicates that the degradation of the resin retards the tree propagation after the tree having failed to penetrate a mica barrier. As the resin is degraded and in part rendered conducting, the partial discharges change both in magnitude and in terms of phase resolved partial discharge patterns. These partial discharge measurements are promising to improve insight into the processes involved in winding insulation ageing, when photographic observations are unattainable. Moreover the differences found between various resins offer an explanation why various types of winding insulation have been found to differ in their capability to withstand thermal cyclic ageing.

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Section: Introductionmentioning

confidence: 91%

Retardation of electrical tree propagation by resin degradation

Weiers¹,

Keller²,

Hutter

et al. 2006

Int Trans Elec Energy Syst

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“…1 shows the test sequence. It is defined according to [2,3]. The aging and diagnostic procedures are successively done on the insulation system model and the procedure is repeated, as shown in Fig.…”

Section: B Test Procdurementioning

confidence: 99%

“…In an accelerated aging test, one or more of the aging stresses are applied to the insulation at a significantly higher level than normally experienced, or at a rate of change which is faster than in normal service. The result is that the insulation deteriorates much more rapidly, causing breakdown in hours or days, rather than years [1,2,3].…”

Section: Introductionmentioning

confidence: 99%

Investigations of diagnostic tools for insulation systems of high voltage rotating machines

Gockenbach

Farahani

Borsi

2010

2010 10th IEEE International Conference on Solid Dielectrics

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In this work the results of extensive investigations on the behaviour of a solid insulation system for rotating high voltage machines with thermal class F (155 °C) will be reported, which was subjected to a thermal overstress (215 °C) in repeated cycles. The test parameters should represent the thermal deteriorating effects of the insulation system in service on an accelerated basis, in order to evaluate the condition of the insulation system in a non-destructive manner. The results indicate how the changes in electrical and dielectric properties of insulation take place during the accelerated aging test.

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“…The groundwall insulation is the main insulation that separates the high voltage copper conductors from the grounded stator core, and the turn or strand insulation prevents shorts between the turns or the strands in a coil. Modern machines use mica flake or mica paper tapes bonded with epoxy or polyester resin as groundwall insulation [1,3].…”

Section: Introductionmentioning

confidence: 99%

“…The result is that the insulation deteriorates much more rapidly, causing breakdown in hours or days, Manuscript received on 15 January 2010, in final form 12 April 2010. rather than years. Such accelerated aging tests have been accepted industry practice for decades [3,4,5]. In particular, the ability of motor and generator insulation systems to resist thermal aging has been established by industry-standard tests at high temperatures [5,6].…”

Section: Introductionmentioning

confidence: 99%

Behavior of machine insulation systems subjected to accelerated thermal aging test

Farahani

Gockenbach

Borsi

et al. 2010

IEEE Trans. Dielect. Electr. Insul.

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Accelerated aging tests have been extensively used on motor and generator insulation systems to simulate in a short time period the deterioration mechanisms occurring during normal operation of many years, to identify insulation system designs with longer life time and to support the qualification of a new system. The contribution presents results from extensive investigations on the behavior of two VPI machine test insulation systems (reference and candidate) with thermal class F (155 °C), which were subjected to three thermal overstresses in repeated cycles. After each thermal cycle the insulation system is subjected to mechanical stress, moisture, and voltage. In order to check the condition of the insulation systems in a non-destructive manner several properties of insulation like dissipation factor, insulation resistance and partial discharge quantities were measured after each thermal cycle. After that the end of life of the insulation systems were checked with ac voltage and impulse voltage. The results support the qualification by comparative evaluation and they indicate, how the changes in electrical and dielectric properties of insulation take place during the accelerated aging test.

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Experience with accelerated aging tests on stator bars and coils

Cited by 23 publications

References 6 publications

Retardation of electrical tree propagation by resin degradation

Retardation of electrical tree propagation by resin degradation

Investigations of diagnostic tools for insulation systems of high voltage rotating machines

Behavior of machine insulation systems subjected to accelerated thermal aging test

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