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The construction of a 42,000 KVA, 28 pole, 13.8 KV hydroelectric generator may be a commonplace occurrence in the factories of the large electrical manufacturers of North America. But it is far from an everyday event in a country such as Brazil. In fact, the machine of this rating now being built in G. E.'s new plant in Campinas should be considered an accomplishment of some magnitude for Americans,...
The rapidly increasing activity in the field of cryogenics has established the need for a precise understanding of the physical and electrical behavior of insulating materials at the very low temperatures involved. Unlike the normal and higher temperature properties which are well-known, there is little background information and accumulated knowledge available to the design and application engineers...
Extreme value statistics have in the last few years been applied to electrical breakdown of insulation with good results. It is considered timely to present a short review of the statistics and at the same time attempt to illustrate the physical reasons for the statistical behavior.
The dielectric losses — dissipation factor, dielectric constant and loss index — are important parameters for selection and control of dielectrics for diverse electrical insulating applications. These properties are indices of the effectiveness of a material as an electrical insulation in a wide variety of applications, are guides for control of quality and lot variations, and are significant guideposts...
Chemists and microwave engineers require instruments which permit the electromagnetic parameters of complex dielectric and permeable media to be continuously determined over wide frequency ranges in the VHF, UHF and SHF region with high accuracy. The manufacturers of ceramic insulants must know the electrical values of their products if these are to be used in special capacitors or as supports or...
It has been amply demonstrated (1, 2, 3) that exposure to oxygen-containing environments above temperatures of 150°C will cause most of the commonly used electrical insulating materials to deteriorate (see Figure 1). Since many of these insulations are used in hermetic structures, life test data based on air aging could be misleading. The emphasis on space electronics in present-day technologies must...
The technology of insulation has accelerated in recent years. The old, time proven insulations have been improved, and new synthetic and natural insulations and composites are frequently appearing. These new insulations add to the difficulty of the designer, in trying to improve his product. His struggles to keep abreast of technological improvements are endless. Present transformer thermal classification...
A new type of polymer, composed of ethylene and propylene monomeric units, has recently entered the industrial rubber field. Due to the saturated nature of the polymer chain, this new rubber, ethylene-propylene rubber, exhibits good electrical properties and excellent resistance to heat, weathering, corona and ozone. These properties, plus its flexibility and low cost (26–30¢/lb), have made it particularly...
There has been considerable confusion for many years as to the significance of thermal classification data for insulating materials. This paper by no means presumes to offer an easy solution to the problem, but merely wishes to discuss the issues and offer suggestions which could lead to an understanding and possibly clarification of the present confusion.
The thermal classification of insulating materials has a long history with the first significant consideration of the subject by Steinmentz and Lamme now fifty years old. Fifty years ago, insulation systems were relatively simple. Arbitrary separation into thermal classes defined by description and supported by operating experience was relatively simple. About 15 years ago it became very apparent...
The insulation field hears much about thermal life, thermal capability, heat aging and various methods of test for determining them. However, a question that usually arises which eventually must be answered is, "What are we trying to measure?" In an effort to seek the answer we propose that: 1. The systems tests be spoken of as compatibility tests and that their results be stated as the...
While considerable progress has been made in the determination of thermal endurance of insulating materials and systems, at times progress seems painfully slow. Perhaps one of the underlying causes for this slowness is that the data obtained from these test procedures often have been misinterpreted and sometimes misrepresented.
I believe the present published methods for establishment of the thermal classification of insulating materials and systems offer a good, practical solution to a problem that has long plagued the designer of electrical equipment.
The major growth area within the printed circuit market is expected to be as a result of the development of flexible and multi-layer circuits. The continuing pressures on designers of electrical and electronic equipment for smaller and lighter packaging has greatly increased the demand for thin, multi-layer and flexible, wiring packages. In the automotive field, dashboard wiring is rapidly being replaced...
For many years the electronic industry has recognized the merits of epoxy resin for environmental protection of equipment and components. The major usage has been confined to equipment of relatively low voltage, but recently there has been increasing interest in applying epoxy resins to higher voltage units where liquids such as mineral oil would normally be used. Applications such as airborne equipment...
Epoxy resins have come into widespread use in the field of electrical insulation. Their unique combination of physical, mechanical, dielectric and handling properties will qualify them as the material of choice in such uses as potting, embedding and encapsulation. They are increasingly specified for high quality and high performance printed circuitry.
In the past, molded encapsulation of components and wire junctions could be accomplished only through the use of expensive equipment specifically designed for each size and configuration.
RTV and heat cured silicone elastomers have for some time been leaders in the materials field for thermal insulation, ablation, and electrical applications for the aerospace industry. The General Electric RTV silicone elastomers had their beginning in the company's silicone research center at Waterford, New York, more than a decade after silicones made their entry into the market as electrical insulating...
Epoxy integral insulation applied in powdered form by means of a spray or fluidized bed process to fractional and integral H.P. electric motors is replacing conventional ground insulation at a rapid rate. Since many of these motors with integral insulation are destined for the appliance market, the Underwriters' Laboratories, Incorporated responded to requests for U.L. listing of such appliances by...
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