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Film insulated magnet wire was the first type of electrical insulating material to standardize a thermal life procedure based on the original work of Dr. Thomas Dakin.1 The procedure was developed by AIEE/IEEE in the 1950's and adopted by NEMA, ASTM and IEC in the 1960's. The expansion of the general aging procedure and the evaluation of other insulating materials has resulted in the development of...
Two kinds of dual coated magnet wires based on electrodeposition process (MEDIS wires) have received practical application to electrical machines in these two years. They consist of electrodeposited epoxy-acrylic layer as a common undercoat and conventional enamels as a topcoat. Polyamideimide and polyvinylformar enamels are used as topcoat of the wires. Polyamideimide overcoated MEDIS wire exhibits...
Stator core testing in a local shop setting has become more and more important over the past few decades with the industry moving to extract greater loads from smaller units creating higher temperatures. These temperatures press the insulation systems to their maximum capability and significantly reduce the allowance of the ever so important "hot spot" in the stator cores. We will explore...
Historically, coated electrical sleeving has been offered in several grades characterized by prescribed minimum voltage breakdown levels determined by means of short time dielectric testing. Various empirical criteria have been used to determine the Jevel of continuous applied voltage which could be considered a safe level for intended applications for these grades in service. To date, no significant...
To raise power per unit weight and improve reliability of DC motors for rolling-stock, we have developed a new insulation system with high thermal endurance by adopting a solventless thermosetting resin for coil impregnation which consists of polyfunctional epoxides and heterocyclic compounds. Evaluation tests have revealed that the insulation system has excellent thermal endurance classified into...
In determining the cost of producing magnet wire, the amount of coating in a quantity of magnet wire enamel is critical. ASTM addressed this concern and established a method of test.1 This method of test has come under much criticism as being unreliable, inaccurate and lacking reproducability. It shall be shown in this paper that the ASTM method of test is an accurate procedure for determining the...
The purpose of this paper is to present supporting data that a series of room temperature stable polyamic acid solutions developed by The P. D. George Co. meet or exceed the requirements of NEMA's MW-16 and the Federal Specifications J-W-1177A/GEN and JW-1177/15A.
This paper deals with the real and hypothetical health risks associated with asbestos containing products. The issues involved have been inaccurately reported by the news media. Most of the information that the general public has received is based on exposure levels that were prevalent 30 or 40 years ago. It is necessary for the industry to provide current data on the environmental impact of asbestos...
A new polyamideimide-ester resin (PAIE) has been developed by the reaction between polyamideimide macromer, polyfunctional carboxylic acids and polyfunctional alcohols. The molecular structure of the PAIE consists of polyamideimide chain which exhibits excellent heat resistance, physical and chemical properties, and a polyester chain which exhibits good flexibility and solubility in conventional solvents...
Magnet Wire used in high temperature environment such as the proximity of the core of nuclear reactor should have a capability of operating temperature 400°C or higher, and also the wire should be free from radiation damage. From these stand points, ceramic insulating wire has been often used in such case that the conventional enamelled wire is not unable to use.
With a view to developing superheat-resistant enameled wires capable of continuous service at 300°C or higher temperatures we studied the applicability of synthetically obtained borosiloxane resins whose chemical structure suggested excellent heat resistance.1 As a result, a solvent-soluble varnish made up mainly of the borosiloxane resins was obtained, and through use of this varnish two types of...
The history and chemistry of solderable and tinnable insulation systems are reviewed. This study shows the evolution of property improvements with changes in the chemistry. Properties of new proprietary systems are presented.
This paper will deal with fibrous glass as it is used in the electrical, electronic, and reinforced plastic industries, and its environmental aspects. Environment is defined in the broadest items, to include both the occupational, as well as the general environment. This paper will deal with the health effects of these materials, and their possible effect on man, as well as the environment, and will...
Polyetherimide (PEI) is a new thermoplastic resin with potential uses in a broad range of electrical applications including magnet wire Insulation, connectors, slot liners, and pressure sensitive tape. The material exhibits high temperature stability, excellent electrical properties, extremely good flame resistance, and durability under a variety of aggressive environmental conditions. As a fully...
When Polychlorinated biphenyls (PCBs) were first introduced on the market as dielectric fluids, they were heralded as a major safety breakthrough. Fire safety codes demanded that PCB transformers and capacitors be used in major buildings. Some insurance companies would not write insurance on buildings that did not have PCB transformers.
Reliable generation requires a comprehensive preventive maintenance program to locate defects and arrest deterioration on electrical generating equipment. This paper outlines one utility's preventive maintenance and investigative practices on hydro-generator insulation systems and describes experience on some of the major repairs and overhauls.
Bharat Heavy Electricals Limited, INDIA manufactures among its diversified products Turbogenerators of rating 2.5 MW to 500 MW & other Electrical machines like AC/DC motors, Synchronous Condensers etc. at 3 of its Major manufacturing Divisions at Hyderabad, Hardwar and Bhopal. The foundation towards improved and reliable insulation system was laid in B.H.E.L., when the first "Epoxy Resin...
Wound electrical coils generally have very limited life while operating under voltage stress in the presence of water. This paper examines some of the failure mechanisms and generates a few ideas which may help to extend this limited life by double, triple or even ten times. Even with this magnitude of improvement, water should be kept off operating electrical coils.
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