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Conductive rubber compounds fabricated into a variety of shapes are increasingly finding their way into military, industrial and consumer electronics products. They have a long history as switching devices in automotive horns, door activated lights and keyboards and are available in four configurations; buttons mounted in insulated carriers, alternating layered connectors (ALC), separate elements,...
Well developed techniques are available for the detection of partial discharges (PD's) in equipment tested in either the laboratory or factory environment. However, because of the need for clean power supplies and an RF shielded environment, most of these techniques are not applicable to on-line equipment. Consequently, recourse must be made to the detection of other signals (related to partial discharges)...
A particularly troublesome problem to the electrical utility industry is the occurrence of tree-like defects in polyolefin insulated transmission cables that have been energized for a period of time in the presence of water. These defects, water trees, are associated with decreased dielectric strength and may be responsible for premature failure of underground cables. Although it is generally agreed...
Studies of changes with aging of distribution cables involve determining the effects of electrical, thermal and environmental stresses on the entire cable system. Changes in the dielectric insulation material are subtle. The materials employed are polyethylene and EP rubber. Differential thermal analysis and differential scanning calorimetry have been employed extensively in studies of changes of...
At some time in an insulation engineer's career a lab must be initially equipped or enlarged. In this photo essay one company's experience will be shared. The first step, to define the mission, is the hardest. While development and quality control are suitable choices, one must take precedence. Second step is to study standard procedures from IEEE, NEMA and ASTM and to write a few procedures specifically...
Mechanical, thermal and electrical design requirements of cylindrical support structures for large generators are demanding. High elastic modulus and matching linear coefficients of thermal expansions in the axial and circumferential directions are required to meet design criteria for successful performance of machines. In order to achieve design objectives, a filament winding process using high performance...
Several types of insulation deterioration common to large rotating electrical machines produce Electromagnetic Interference (EMI) at discrete frequencies or within bands of frequencies. This paper employs the use of standing wave calculations to predict these natural resonant points. Curves of measured impedance variation with frequency are presented to verify calculated values. Determination of these...
As laboratory costs continue to escalate, the need for accurate test results with minimum test hours becomes increasingly important. Utilization of censored test data is one means to this end. This paper will present support for the use of censored data. It is based on the comparison of results of 85 sets of complete thermal aging data used for component recognition. In this comparison the same data...
Recently developed mica paper tapes designed for the VPI-process for high voltage rotating machines offer the great advantage over conventional tapes, that the impregnation with epoxy resins of higher viscosity is possible. Therefore substantial cost savings are attained as the increase of viscosity of the impregnant is less critical than has been the case up to now. This is especially important for...
A newly developed adhesive tape which utilizes conductor stripes with a range of center-to-center spacings produces reliable, cost effective, multiple electrical connections to liquid crystal displays (LCD), printed circuit boards (PCB), membrane switches and terminal pads on other components. A continuously striped tape in a roll format allows bonded connections to be made at any point using a rapid...
NEMA MW-1000 is a viable document that is continuously upgraded to meet the Magnet Wire Industries needs. This paper will cover the activities of the NEMA Magnet Wire Section during the period of 1982–1983. Part I of MW-1000 has been revised quite extensively, both editorialy and technically. Two new standards have been added to MW-1000 and three more are nearly complete. A number of new test procedures...
UL 1446 — Systems of Insulating Materials — General, required a reevaluation of electrical systems. This reevaluation included an upgrading of electrical impregnating insulating varnish to a primary insulation component. A massive program was then undertaken by the resin industry to establish component recognition values for the varnishes. Testing was conducted on all types of varnishes. Each product...
The radiation resistance of three popular families of insulating varnishes was investigated. The materials selected included oil modified polyesters, solventless epoxies, and unsaturated sol-ventless polyesters. A representative material from each of the families was evaluated in terms of electrical and mechanical performance, exposed to an intense beam of electron radiation, and then re-evaluated...
Successful manufacture of modern thermosetting Class F epoxy Mica Mat high voltage stator winding ground insulation for hydrogenerators requires rigorous attention to material input, manufacturing process detail and quality assurance. The CGE manufacturing process is described while the quality assurance program is highlighted.
A new coil insulation system which is based on electrodeposition of mica flake has been developed. The system is able to eliminate taping process and has better electrical and heat resistant characteristics than conventional tape wound insulation system. It has been applied to layer insulation of armature coil for a traction motor. A new automatic plant for this insulation system aids reliable manufacturing...
European Standards for rotating machines include rules for acceptance tests on high voltage winding insulation. The standard claims for dielectric loss and dielectric strength measurements and contains a thermal short time stability test of single bars or coils. This paper describes the test methods and the values of the acceptance limits. Examples will be shown how dielectric loss measurements serve...
The trend to higher efficiency motors and operations has created the need for a new family of Electrical Insulations Systems for Magnet Wire. These needs are being met with modifications of current technologies and applying new chemistries to existing technologies. The use of improved lubricants which allow more dense packing of the wires in a given slot has initiated the development of a "thermosetting"...
The bondable system concept provides a strong, uniform bond between all components of a motor, transformer or coil. Only two major components were changed when converting from a conventional insulation system to a bondable system. These components were: bondable magnet wire and "B" stage resin treated sheet and tape insulation. Bonding of the system may be accomplished by resistance or oven...
During the 10-III-82 period, the Western Electric Montgomery Works began experiencing microscopic cross solders (microshorts) on numerous data set printed wiring board assemblies (circuit packs). The microshorts were generally observed on fine line circuit packs (.010" lines and spaces) after the machine soldering operation. Three conveyorized in-line assembly/soldering processes which were involved...
Multi-functional testing of an insulation system is gaining more recognition and acceptance as indicated in IEEE Standard 434-1973. Thermal aging is only one factor causing deterioration of all insulation systems. Voltage stress along with thermo-mechanical forces, electro-mechanical forces and environments are also destructive. This paper reviews the various physical / mechanical functions of solventless...
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