An Advanced Concept for Turbine-Generator Stator-Winding Insulation

Flynn, Errol; Kilbourne, C. E.; Richardson, Christopher D.

doi:10.1109/aieepas.1958.4499937

Cited by 22 publications

(3 citation statements)

References 4 publications

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“…The bars were clamped between aluminum bars to ensure a defined ground potential and simulate a real stator slot. MicaMat [19] Micadur [20] The bars were divided into two groups, as shown in Table 2. The Group B spare bars were still spare for a generator in service, and testing could not be destructive or degrade the bars by any chance.…”

Section: A Test Objectsmentioning

confidence: 99%

Partial Discharge Activity in Rotating Machine Type II Insulation Systems as a Function of Temperature and AC Supply Frequency

Aakre

Kantar

Eberg

2023

IEEE Trans. Dielect. Electr. Insul.

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The main purpose of this study was to investigate if the application of very low frequencies for PD measurements in type II generator bar insulation is relevant when compared to applying power line frequency at different test temperatures. Laboratory experiments were performed on two stator bar types rated 6.4 kV and 7.4 kV, labeled as Group A and Group B. The stator bars were taken from service and spare part storage (pristine). The samples were preconditioned at the maximum test voltage of 1.5 U0 before sweeping the AC high voltage supply from 0.1 Hz and 50 Hz. The test temperature was varied between 20 °C and 155 °C. Investigation of cross sections of the generator bars was done to qualitatively describe the voids. The main results showed that the partial discharge inception voltage (PDIV) for Group A was temperature independent at 50 Hz and decreased by 40 % at 0.1 Hz with increased temperatures, whereas the PDIV for Group B was frequency independent and increased by 70 % with temperature. Similarly, the PD magnitude and total apparent charge decreased by 90 % for Group B with increased temperature, whereas it more than doubled for Group A with temperature. The tested bars from Group A showed significantly larger voids, located close to the copper conductors, compared to Group B, where voids were mainly located within the mainwall insulation. Results indicated that tests performed at 0.1 Hz cannot directly represent results obtained at 50 Hz. Using a wide range of frequencies and test temperatures broadens the understanding of the behavior of the voids inside the mainwall insulation.

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Section: A Test Objectsmentioning

confidence: 99%

Partial Discharge Activity in Rotating Machine Type II Insulation Systems as a Function of Temperature and AC Supply Frequency

Aakre

Kantar

Eberg

2023

IEEE Trans. Dielect. Electr. Insul.

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“…the structure of the mainwall insulation is shown in figure 1. since the 1950s, mica-based mainwall insulation has been reinforced with glass fabric and bonded with synthetic resins [8], [9]. Insulation of this kind replaced the older construction of mica paper, cotton cloth reinforcements, and asphalt varnish.…”

Section: Mainwall Insulationmentioning

confidence: 99%

Fortifying Subsea Wells: A Comparative Analysis of Mainwall Insulation Materials Used in Natural Gas Production

Sihvo

Nerg

Pyrhönen

et al. 2013

IEEE Ind. Appl. Mag.

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A comparative analysis of mainwall insulation materials used in natural gas production FortiFying SubSea WellSFortiFying SubSea WellS B y v I l l E s I h v o , J A n n E n E r g , J u h A p y r h ö n E n , & l A r s B r E n n E atural gas recovery from subsea wells is increased by an artificial lift, which can be provided by a compressor installed at the wellheads. such a machine is driven by a high-speed, high-voltage electrical motor that is integrated into the same casing as the compressor. the motor is cooled by the process gas bled from the compressor itself. because the insulation system is in direct contact with the process gas, it must have good chemical resistance and high mechanical strength to withstand the environment.various types of mica-based mainwall insulations were exposed to an environment consisting of: 1) hydrocarbon gas, 2) condensate, and 3) a mixture of produced water and monoethylene glycol at 150 bar and 130 °c. changes in the mechanical properties were

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“…In 1958, G.E. has used the mica-tape and the epoxy resin for a new insulation system [25]. Both insulation systems exhibited better performances under high temperature conditions compared to older insulation systems (asphalt-mica).…”

Section: Bonding Material: the Epoxy Resin The Weakest Part Of The Imentioning

confidence: 99%

The Insulation for Machines Having a High Lifespan Expectancy, Design, Tests and Acceptance Criteria Issues

Barré¹,

Napame²

2017

Machines

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Abstract:The windings insulation of electrical machines will remain a topic that is updated frequently. The criteria severity requested by the electrical machine applications increases continuously. Manufacturers and designers are always confronted with new requirements or new criteria with enhanced performances. The most problematic requirements that will be investigated here are the extremely long lifespan coupled to critical operating conditions (overload, supply grid instabilities, and critical operating environments). Increasing lifespan does not have a considerable benefit because the purchasing price of usual machines has to be compared to the purchasing price and maintenance price of long lifespan machines. A machine having a 40-year lifespan will cost more than twice the usual price of a 20-year lifetime machine. Systems which need a long lifetime are systems which are crucial for a country, and those for which outage costs are exorbitant. Nuclear power stations are such systems. It is certain that the used technologies have evolved since the first nuclear power plant, but they cannot evolve as quickly as in other sectors of activities. No-one wants to use an immature technology in such power plants. Even if the electrical machines have exceeded 100 years of age, their improvements are linked to a patient and continuous work. Nowadays, the windings insulation systems have a well-established structure, especially high voltage windings. Unfortunately, a high life span is not only linked to this result. Several manufacturers' improvements induced by many years of experiment have led to the writing of standards that help the customers and the manufacturers to regularly enhance the insulation specifications or qualifications. Hence, in this publication, the authors will give a step by step exhaustive review of one insulation layout and will take time to give a detailed report on the standards that are linked to insulation systems. No standard can provide insurance about lifespan, nor do any insulation tests incorporate all of the operating conditions: thermal, mechanical, moisture and chemical. Even if one manufacturer uses the standards compliance to demonstrate the quality of its realization; in the end, the successful use in operation remains an objective test. Thereafter, both customer and manufacturers will use the standards while knowing that such documents cannot fully satisfy their wishes. In one 20-year historical review, the authors will highlight the duration in insulation improvements and small breakthroughs in standards writing. High lifespan machines are not the main interest of standards. A large part of this publication is dedicated to the improvements of the insulation wall to achieve the lifespan. Even if the choice of raw materials is fundamental, the understanding of ageing phenomena also leads to improvements.

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An Advanced Concept for Turbine-Generator Stator-Winding Insulation

Cited by 22 publications

References 4 publications

Partial Discharge Activity in Rotating Machine Type II Insulation Systems as a Function of Temperature and AC Supply Frequency

Partial Discharge Activity in Rotating Machine Type II Insulation Systems as a Function of Temperature and AC Supply Frequency

Fortifying Subsea Wells: A Comparative Analysis of Mainwall Insulation Materials Used in Natural Gas Production

The Insulation for Machines Having a High Lifespan Expectancy, Design, Tests and Acceptance Criteria Issues

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