The Experts below are selected from a list of 2220 Experts worldwide ranked by ideXlab platform

F.t. Emery - One of the best experts on this subject based on the ideXlab platform.

  • Fundamentals of testing mica epoxy Stator Coils for high voltage electric generators
    IEEE Transactions on Dielectrics and Electrical Insulation, 2010
    Co-Authors: F.t. Emery
    Abstract:

    There are numerous tests performed on Stator Coils designed to operate in high voltage electrical generators. There are tests performed to qualify a Stator Coil design. There are tests that are performed on each production Coil at various steps in its production cycle. There are tests performed as a quality check and verification. And there are tests performed on fully assembled generators relative to the Stator Coils. There are mechanical, electrical, and chemical tests performed on high voltage Stator Coils. There are also tests performed on the separate materials that go into the fabrication of the Stator Coils. In addition, there are tests performed on an operational generator at various stages of it's in service life. This paper describes the tests performed on the basic Stator Coil relative to many aspects of the Coils and relative to many steps during production.

  • High dielectric performance Stator winding insulation system for global VPI'ed air cooled generators
    Proceedings: Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Technology Conference (Cat. No.03CH37480), 2003
    Co-Authors: F.t. Emery
    Abstract:

    Stator winding insulation system for modern global vacuum impregnated (VPI'ed) air cooled generators are designed to perform under high electrical, mechanical, and thermal stress. Each component of insulation that goes into the fabrication of the Stator Coil is selected and tested to a very high standard so the Stator winding will withstand these stresses over it's intended lifetime. Operation of the Stator winding in an air environment means the Stator Coil design must meet a very high standard of dielectric requirements. With the movement to increasing the power density of air-cooled generators, it has become more critical to be sure the design constraints are met in the Stator Coil design. Stator Coil insulation stress factors are well known and for the most part understood and are taken into account when designing global VPI'ed air cooled generator Stator windings. In addition to selection of the best available Coil materials, special design considerations are incorporated into the Stator Coil to reduce internal and external Coil corona. Significant advances have been made in the testing and analysis of Coil materials prior to their use to ensure the Coils are fabricated using the correct materials and to ensure the materials meet their original design parameters. In addition to the use of high performance Coil materials and special design features, the global vacuum-pressure-impregnation equipment and process control are critical factors to insure the winding meets the stress factor demands. To verify final Stator fabrication, impregnation, and proper cure, final testing of the completed Stator winding includes power factor testing, corona inception testing and the standard AC high potential testing. This paper presents the major features of the Stator insulation system used in the modern global VPI'ed air cooled generators and what measures are taken to be certain the completed Stator winding will meet the high demands placed on it during generator operation.

  • Stator Coil insulation for modern air-cooled generators
    Proceedings: Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Conference (Cat. No.01CH37264), 2001
    Co-Authors: F.t. Emery
    Abstract:

    Stator Coils in modern air cooled generators are subject to high electrical, mechanical, and thermal stress. In addition, operation in the air environment doesn't offer the dielectric advantages of operating in high pressure hydrogen. These three insulation stress factors are well known and for the most part understood with respect to the factors taken into account when designing air cooled generator Stator windings. These three stress factors are considered when selecting the Coil materials, the Coil geometry, and the rating capabilities of the Stator Coil. With the movement to increasing the power density of air-cooled generators, it has become more critical to be sure the design constraints are met in the Stator Coil design. In addition, the Coil materials and processing must be improved to meet the demands of the increased stress factors. In addition to the use of high performance Coil materials, great improvements have been made in the analysis, testing, and the use of more sosphicated instrumentation for verification testing. The Stator Coil insulation system used in the modern air cooled generators are designed to meet the high demands placed on the system during generator operation.

  • Improved groundwall insulation system for air cooled generators
    IEEE Power Engineering Society. 1999 Winter Meeting (Cat. No.99CH36233), 1999
    Co-Authors: F.t. Emery
    Abstract:

    A new insulation system has been developed for Coils that are used in air cooled generator Stator windings. The power density of these air cooled generators can be increased through better thermal performance of the Stator Coil insulation. The approach taken to achieve better thermal performance is to reduce the groundwall insulation thickness and at the same time improve the Coil's dielectric parameters. This paper describes a new air cooled Stator Coil insulation design that incorporate design improvements in three major areas of the Coil's insulation components. These are the groundwall insulation, the Roebel filler material, and the external corona suppression. Each of these improvements are reviewed with respect to the role they play in the overall dielectric performance of the new Coil design.

  • Voltage grading model for high voltage electric generator Stator Coil end turn regions
    1998 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.98CH36257), 1998
    Co-Authors: F.t. Emery, D.c. Johnson
    Abstract:

    Semiconductive tapes are applied to the end turn region of high voltage Stator Coils to reduce corona discharge at the slot exit region. The nonlinear, stress grading tapes are used to even out the voltage stress resulting in a more even distribution which also reduces the maximum stress level. To be able to optimize the stress grading capabilities of the insulation design and the stress grading electrode, it is necessary to be able to accurately calculate the end turn voltage distribution. In order to be able to calculate the voltage distribution, a model of the end turn region was developed. The equivalent circuit models the capacitance between the insulation and the conductor, as well as the nonlinear stress grading characteristics of the voltage grading electrode. The model is used to calculate and demonstrate a typical voltage distribution. The voltage distribution predicted by the model is shown to be in agreement with experimental measurements.

S H Jayaram - One of the best experts on this subject based on the ideXlab platform.

  • effectiveness of stress grading coatings on form wound Stator Coil groundwall insulation under fast rise time pulse voltages
    IEEE Transactions on Energy Conversion, 2005
    Co-Authors: F P Espinocortes, E A Cherney, S H Jayaram
    Abstract:

    In this paper, the effectiveness of stress grading coatings (SGCs) on form wound Stator Coil groundwall insulation under fast rise time pulses is analyzed. The combined performance of the stress grading coating and the semiconductive slot coating is studied under fast rise time transient voltages. During the rapid rise of voltage, the high stress moves from the stress grading coating to the semiconductive coating at the end of the slot. According to the results, it is evident that the design of both the stress grading and semiconductive slot coatings must be done together for effective stress relief. The use of materials with varistor behavior in the stress grading coating, combined with a high conductivity semiconductive slot coating, is analyzed as a solution to the high stress that develops at the slot end of form wound Stator Coil groundwall insulation of inverter fed drive (IFD) motors.

F P Espinocortes - One of the best experts on this subject based on the ideXlab platform.

  • effectiveness of stress grading coatings on form wound Stator Coil groundwall insulation under fast rise time pulse voltages
    IEEE Transactions on Energy Conversion, 2005
    Co-Authors: F P Espinocortes, E A Cherney, S H Jayaram
    Abstract:

    In this paper, the effectiveness of stress grading coatings (SGCs) on form wound Stator Coil groundwall insulation under fast rise time pulses is analyzed. The combined performance of the stress grading coating and the semiconductive slot coating is studied under fast rise time transient voltages. During the rapid rise of voltage, the high stress moves from the stress grading coating to the semiconductive coating at the end of the slot. According to the results, it is evident that the design of both the stress grading and semiconductive slot coatings must be done together for effective stress relief. The use of materials with varistor behavior in the stress grading coating, combined with a high conductivity semiconductive slot coating, is analyzed as a solution to the high stress that develops at the slot end of form wound Stator Coil groundwall insulation of inverter fed drive (IFD) motors.

M L Miller - One of the best experts on this subject based on the ideXlab platform.

  • Turbine generator Stator slot thermal conductivity
    Proceedings: Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Conference (Cat. No.99CH37035), 1999
    Co-Authors: M L Miller
    Abstract:

    Thermal power dissipation from vacuum pressure impregnated Stator Coils to the Stator core in turbine generators is a topic of technical importance. In order to increase turbine generator MVA output by increasing current through the Coil wire strands, there must be improved thermal conductivity in the Stator slot to improve thermal power dissipation capability. A benchmark study of vacuum pressure impregnation (VPI) and global vacuum pressure impregnation (GVPI) Stator Coil groundwall insulation has been investigated in a previous paper (1997). This paper builds on the model showing a relationship between the Stator Coil groundwall insulation composition and thermal conductivity. This paper looks at improving the Stator slot thermal conductivity by increasing the thermal conductivity of the Stator Coil groundwall insulation and the region between the Stator Coil and the core. The models generated provide a design tool which can estimate the thermal conductivity in the Stator slot, from the Coil wire strands to the core.

  • Achieving high voltage dielectric breakdown of turbine generator Stator Coils using capacitors
    1998 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.98CH36257), 1998
    Co-Authors: M L Miller
    Abstract:

    High surface electric field gradients are generated between the Stator half-Coil straight section grounding and the Coil involute region. Surface flashover at electric stresses typically less than the dielectric strength of the groundwall often occurs. Oil or SF/sub 6/ immersion to prevent surface flashover is not feasible for these very large size of Stator half Coils. The surface flashover voltage has been used as a lower estimate of performance capability by Westinghouse. To determine the capability of Westinghouse Thermalistic/sup (R)/ groundwall, an electrical circuit has been devised to suppress the intensity of the surface voltage gradient across the involute region. The test circuit using high voltage capacitors allows the dielectric strength of the Thermalistic/sup (R)/ groundwall to be measured. The new testing circuit can be used to prevent over-design and the associated added cost to Stator Coil bars. The author will introduce the application of using capacitors to achieve dielectric breakdown of Stator Coil groundwall.

  • thermal conductivity of high voltage Stator Coil groundwall insulation
    Electrical Insulation Conference, 1997
    Co-Authors: M L Miller, F.t. Emery
    Abstract:

    A current topic of interest and technical importance is the thermal conductivity of the vapor pressure impregnated (VPI) groundwall and the Stator core slot contents. In order to improve turbine generator performance, there must be improved thermal conductivity for increased thermal power dissipation capability in the Stator slot. A benchmark study of the current Westinghouse VPI Stator Coil groundwall insulation including modeling to estimate thermal conductivity has been investigated. This paper presents a model showing a relationship between the VPI groundwall insulation composition and thermal conductivity. The VPI groundwall insulation thermal conductivity model compares very well with physical measurements. The model generated provides a materials design tool which can estimate composition effects on thermal conductivity of Stator Coil groundwall insulation.

He Sheng-xi - One of the best experts on this subject based on the ideXlab platform.