The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The development of one part powdered epoxy resins for spray and fluidized bed use has given the electric motor industry a new approach to ground insulation. Refinements of the epoxy systems to provide high edge coverage, high cut-through resistance, and no post cure makes them even more attractive to the motor manufacturer. The advantages of integral insulation over conventional ground insulation...
This paper summarizes data obtained on the voltage endurance and corona resistance of various electrical insulations in sheet and film form. The method of testing and its limitations are discussed. The improvement in voltage endurance and corona resistance obtained by incorporating oriented mica flake in various organic insulation systems is shown.
The whole useful life of hydrogen-cooled turbogenerators must be considered in planning generator operation and maintenance practices. Factors to be considered in planning an operating program include cyclic loading, stator and rotor temperatures, core temperatures, differential expansion, expected useful life of turbogenerator, system configuration, etc.
The long range scheduling of periodic maintenance on large turbine generators is of increasing importance with units of larger generating capacities, and the corresponding higher penalty for forced outage time. With larger machine sizes go increased magnetic and mechanical forces, more complex equipment, and more auxiliary equipment, as well as more automation of the entire system. Planned maintenance...
One of the first practical industrial applications of electric power some 75 years ago was a motor turning a shaft. Both the magnitude and diversity of motor applications have since had a tremendous growth, and in the more recent years this trend has been increasing rather than diminishing. In many industries, particularly the chemical industry, the environment in which the motor must operate has...
The need for weatherproof-chemical resistant insulation systems for form wound pre-insulated motor field coils has received greater emphasis in recent years. This has been due partially to the desire to use lower cost open-frame motor designs and to the advent of new electrical insulating materials capable of withstanding moist and corrosive environments.
Economics of manufacturing has dictated that the indoor housing of process facilities be limited to the minimum possible, that necessary only to protect the products. Where the material in process is housed in pipes, totally enclosed vessels, etc., it does not usually need additional weather protection, so the trend toward completely outdoor plants has become the rule rather than the exception.
The insulation of high voltage stator windings for electric utility generators must have a very high order of reliability. Machines of this category have always been of extreme importance because of their size with the accompanying high capital investment and the dependence of so many things in our society upon their continuous and uninterrupted operation. Lately, the size of these machines, particularly...
The rapid progress of the more glamorous areas of electronic technology, such as microelectronics, tends to obscure the continuing evolution of some of the older forms of technology applied; for example, to electronic transformers. This evolution for transformers, while proceeding at a slower pace, is resulting in greater integration and interdependency of the various aspects of electronic transformer...
Materials produced by crystallization of glass present a unique combination of properties such as homogeneity, pore-free structure and small particle size, which is controllable by heat treatment within the 0.1 to 1 micron range. Furthermore, shaping and sealing operations are possible in the glass state.
Liquid dielectrics have been successfully used for many years for the major insulation system impregnate for transformer applications above 10–25 KV operating levels. Extensive use of liquid insulants is based primarily on their ability to satisfy the prime design requirements of low cost, long service life with a minimum of maintenance, good dielectric, thermal properties and compatibility with other...
H Film is the designation for a new high-temperature polyimide film under development by the Film Department of the Du Pont Company. It is a product of the same research effort which produced the Fabrics and Finishes Department's "Pyre-M.L."1 enamel and "Pyre-M.L." varnish, both of which are being used by the electrical industry for high temperature insulation. A chemically different...
Over the last few years, the surge test has become a very common useful tool for analyzing the quality of electrical equipment. Test stands are commercially available for installation on production lines whereby units such as stators can be quickly examined for electrical properties turn to turn, phase to phase, or coil to ground. Usually, the unit under test is compared to a "standard"...
There is no subject which is so fraught with empiricism as surface flashover. A tremendous amount of work has been done on the subject of breakdown in gases, solids and liquids, but practically all of it is for uniform fields in isotropic systems. When we mix a solid with a gas or a liquid so that the field is not uniform, the amount of surface, the condition of the surface and the disposition of...
In order to determine the adequacy of a dielectric, a testing program must be devised that covers the three areas of possible dielectric deficiencies. These modes of dielectric failure may be reviewed briefly as follows: The intrinsic strength of a solid dielectric is that which relates to its atomic structure. The breakdown mechanism of this mode takes place when the applied electric field is strong...
Today, with the development of switchgear and circuit breakers aimed toward increased ratings while the physical size is steadily becoming smaller, we have to put greater emphasis on our electrical insulation requirements. Because of these conditions, we have to review our requirements with greater care than before and have to give more consideration in the selection of materials and their properties.
In many areas of electrical equipment — generators, for example — the constant push toward greater performance levels has made necessary a frequent reappraisal of the materials available for design purposes. This is no less true in switchgear. In the case of arc barriers, the number of available materials has in the past been fairly limited to a group of organic-bonded laminates on the one hand and...
Studies have been made of transformers and similar equipment in which various faults have been associated with the formulation of combustible gases(1). It has been shown there are many reasons for the formation of combustible gases(2), but not all of the causes are necessarily faults. As more and more emphasis is placed on preventative maintenance of electrical equipment, the need for a thorough understanding...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.