Aluminum Windings Research Articles

Solar Plane Propulsion Motors With Precompressed Aluminum Stator Windings

This paper reports a propulsion motor for a solar-powered aircraft. The motor uses precompressed aluminum stator windings, with a fill factor of greater than 75%, in a permanent magnet synchronous machine. The motor performance is compared empirically to an identical machine with conventionally wound copper windings. It is shown that there are many advantages to using compressed aluminum windings in terms of weight reduction, thermal improvement, and lower cost, for the same loss and electromagnetic performance, provided a sufficiently high slot fill factor can be achieved. The design and manufacture of the compressed coils is also discussed. A modular stator arrangement is used, in the form of a solid coreback with keyed teeth to allow easy assembly of the compressed windings. It is noted that the electromagnetic performance of the machine is unaffected by the modular nature of the magnetic core. Two prototype motors, one wound with conventional copper and the other with precompressed aluminum windings, are constructed and tested.

Ventilation Fan Fires: Overheated Windings Lead to Failed Thermal Limit Switch

Over the last several years, the forensic community has experienced an increase in the number of fires which have been attributed to ventilation fans. These failures have been anecdotally observed in Jakel motors, specifically model numbers J239-050-5138 and J238-050-5494, manufactured between 2000 and 2003. While there have been a number of variations to motors within exhaust fans over the preceding decades, including different winding size, winding metal, and thermal cut-off (TCO) manufacturers, two design implementations have led to the higher incidents of failure. The first design change is the implementation of 27 American Wire Gauge aluminum winding (magnet) wire. The second, and most important, is the implementation of the Tamura Thermal Device Corporation (TAM) TCO to replace the Elmwood Sensor/Honeywell (Elsen) TCO. Through investigations and testing, the Tamura TCO has been found to be unreliable at opening the circuit within the motor when exposed to temperatures above its specified cut-off temperature (136°C). Thermal testing of a Tamura TCO showed that even when exposed to temperatures as high as 260°C, the flux of the fusible thermal link is incapable of breaking down the oxides created by the metal alloy. The hypothesized failure mechanism for the Tamura TCO include increased exposure to high temperatures during fan operation and/or air infiltration from cracks in the epoxy sealant due to improper installation, along with the corrosive effects of the chlorinated flux. This work presents case studies, experimentation, and analysis of the failure mechanisms related to fires associated with the aforementioned motors.

Сравнение характеристик асинхронного двигателя с короткозамкнутым ротором при замене материала обмотки ротора и предложения по их улучшению

Have been analyzes the questions of the changes the geometry toothed zone asynchronous motor rotor, that must be done when changing the material of the rotor winding. It is noted that the use of the asynchronous generator with wound cast copper rotor winding instead of cast aluminum winding, is not a problem. But for motors with rotor copper windings should conduct additional studies to ensure acceptable starting characteristics and conservation of energy indicators. It was found that the deepening of rotor slot by 15 % will lead to increased influence of crowding out current and will provide for the asynchronous motor with a copper rotor winding same starting characteristics, which have been the engine with aluminum one. The results were obtained under the condition of conservation cross-sectional area of the groove, i.e. copper consumption and cost.

Design and Analysis of the Quench Protection System for the MICE Coupling Coils

Two identical MICE coupling coils have the largest diameter and stored energy, at 13 MJ each, of all coils in the Muon Ionization Cooling Experiment (MICE). The coils have an inner diameter of 1.5 m and radial and axial builds of 102.5 and 285 mm, respectively. The coils contain approximately 15 936 turns and are wound with a single rectangular NbTi strand with a copper-to-superconductor ratio of 3.9:1. Each coil is conduction cooled using three cryocoolers, which maintain an operating temperature at about 4.5 K. Each coil is powered through a pair of series-connected copper and 500 A HTS current leads. The quench protection analyses described here show that subdividing the winding into four or more, cold-diode-protected subsections maintain hot spot temperatures below 150 K and internal winding voltages below 300 V. The superconducting subdivision interconnect loops are protected by heat sinking them to the aluminum winding housing. Stabilizing the coil leads from the winding to HTS current leads minimizes the likelihood of lead quench. The first of three coils will be tested at Fermi Lab and the final two coils will be installed in MICE at Rutherford Laboratory.

Modeling and optimal design of relative position detection sensor for high speed maglev train

The long stator track for high speed maglev train has a special tooth-slot structure. The relative position detection sensor obtains precise relative position information for the operation control system by detecting the changing coil inductance reflecting the long stator tooth-slot structure. The aluminum windings are inlaid in the stator slots, and the magnetic field due to the sensor coils induces eddy current in them, which would change the magnetic field distribution and have a significant influence on the sensor. In this paper, the multipole theory (MT) is adopted to build the analytical electromagnetic model of the sensor. Based on the electromagnetic model, the influence of the eddy current induced in the windings on the coil inductance is studied. The DC offset formula of differential voltage owing to the slight inductance difference of the coils is derived. The influence of the eddy current on the DC offset is analyzed, based on which, a method of no-load voltage compensation and an optimal sensor excitation frequency is proposed to improve the accuracy of the sensor.

Design of Copper-Clad Aluminum Winding Alternator for Vehicle Application

Copper-clad aluminum wire which is composed of aluminum core clad with ETP copper was exploited to solve the problem of the copper price increasing by replacing traditional copper wire with copper-clad aluminum wire in the alternator for vehicle application. The aluminum winding alternator parameter was designed and the alternator was tested. The test data show that copper-clad aluminum can offer most of the advantages of aluminum, such as having lighter weight and lower cost than copper, but without the main perceived disadvantages of aluminum. With right parameter and well welding, aluminum winding can replace copper winding to reduce the alternator cost.

Selection of copper against aluminium windings for distribution transformers

Copper and aluminium are the two conductors most commonly used in transformer windings. This study presents a comprehensive comparison of distribution transformers built either with copper or with aluminium windings. The comparison is based on winding material conductivity, density, cost, connectivity, oxidation, machinability and behaviour under short-circuit. Additionally, a parametric analysis of transformer designs as a function of the cost of copper against aluminium is presented. The study establishes the winding material cost range that indicates when it is more economical to build the transformer windings with copper or with aluminium. All comparisons are carried out with cost of optimised transformer designs that fulfil all specifications together with manufacturing and operating constraints.

New Technologies in Ammonia Refrigerating and Air-Conditioning Systems

This review paper describes a brief historic perspective of transition from natural refrigerants to synthetic and now back to natural refrigerants. The thermodynamic, physical and safety properties of ammonia are presented. The advantages and disadvantages of ammonia refrigerant are discussed. The heat exchanger technology has seen introduction of compact and efficient equipment both in shell and tube and plate technologies. The micro-channel exchangers are being introduced in the automotive industry and it could soon enter into the commercial and industrial refrigeration markets. Compact heat exchangers are of interest due to their low refrigerant inventory features. A new electromotor technology is being developed now, using encapsulated copper windings or aluminum windings for semi-hermetic ammonia compressors. A hermetic scroll compressor for ammonia small refrigerating systems is also in the offing. In the last several years large numbers of air conditioning systems with ammonia chillers have been installed in commercial and public facilities. In large industrial systems where there is a need for low evaporating temperatures, Ammonia/Carbon Dioxide cascade systems are being proposed and installed.

Aluminum Windings and Other Strategies forHigh-Frequency Magnetics Design in anEra of High Copper and Energy Costs

Recent Cu price increases motivate careful examination of approaches to minimize Cu use in high-frequency transformers and inductors. Approaches that can reduce Cu use without increasing losses include careful winding design, trading winding volume for core volume, replacing Cu with Al, and using Cu-clad Al (CCA) windings. Al wire is particularly attractive. The cost of Al is lower than it might appear from the cost per unit mass when the much lower density of Al is also considered, and the disadvantage of higher resistivity becomes less important when high-frequency effects are considered.

High-speed compulsator stator thermal management

The compulsator stator armature winding includes multiple conductor layers. Each conductor layer is made of insulation wraps and transposed aluminum litz wire bundles with epoxy potting compound between the wires and the wire bundles. For a typical pulse-duty application, based on a room-temperature electrical loss calculation, the temperature rise in the aluminum winding is approximately 30/spl deg/C per shot. Adequate active cooling must be provided such that the stator insulation can survive thermally under a certain pulse repetition rate. As a result of the low equivalent thermal conductivities of the stator winding in the transverse direction, without compromising the overall structural integrity of the winding, the coolant passages have to be allocated as close as possible to the heat sources. For a given electric gun firing mission, four different cooling configurations have been investigated and analyzed by using water ethylene glycol mixture as an active liquid coolant. In this paper, thermal analysis cooling parameters, transient stator winding temperature distributions, and hot-spot temperature histories are presented, discussed, and compared.

Design Considerations for the Use of Aluminum Alloys for Integral Horsepower Motors

The design considerations on the use of aluminum alloys for the external supporting parts of integral horsepower induction motors are compared with the previously conventional use of cast iron. Covered are such factors as type of aluminum alloy selected considering service requirements and manufacturing methods planned, strength, reliability, durability (including corrosion resistance), effect on overall weight and performance. The tests made to check suitability of actual results against design plans are briefly described. In addition, the considerations and tests required to use aluminum windings alternatively with copper are discussed.

Corrigendum: Aluminium windings for hydroelectric generators: a critical analysis

Corrigendum: Aluminium windings for hydroelectric generators: a critical analysis

Aluminium windings for hydroelectric generators: a critical analysis

There has been considerable progress in substituting aluminium for copper in electrical apparatus such as busbars and transformers, but little or none in rotating electrical machines. Making certain simplifying assumptions, the paper evolves a mathematical analysis for salient-pole generators by which the losses, dimensions and cost of a generator with aluminium windings, with the same rating and short-circuit ratio (s.c.r.) as one with copper windings, can be evaluated. An extension of the analysis permits a price comparison to be made both without and with the capitalisation of losses. These results are displayed as families of curves with either gap diameter, or cost of copper, as the independent variables. An appendix considers the substitution of aluminium for copper in the stator winding only. Worked examples are given of a medium-speed and a low-speed hydroelectric generator, and the results show that, for the medium-speed type to become an economic proposition with aluminium windings, the price of copper must increase by about 20%, whilst for the low-speed type an increase in the price of copper of only about 5% is sufficient. These conclusions may be modified in countries developing their industrial capacity with ample indigenous aluminium, but importing copper. Here the reduction of the drain on foreign credits by restricting the import of copper may be the paramount consideration.

Use of Aluminum Coils Instead of Copper Coils in Accelerator Magnet Systems

Use of aluminum windings for the ac injector-synchrotron and dc storage ring magnet systems has been studied. 1, 2 The injector synchrotron is an 18-Hz fast-cycling 8-GeV accelerator that feeds protons to the 200-GeV main ring. The physical properties of aluminum are discussed, as are the extrusion of the conductor and the winding of the coils. Also included is a discussion of cooling-system problems and their solution. Important design conditions for aluminum coils are given. An economic analysis of aluminum- and copper-coiled magnet systems is presented. As an example, the injector-synchrotron magnet system is compared to a dc storage-ring magnet system with the same magnetic characteristics. The optimum coil current density is discussed, as are the effect of gap field, economic life, and core shape on cost and optimum current density. Physical and economic advantages of aluminum coils for magnet systems are presented as are conditions under which the use of aluminum coils should be avoided.

Pure metal AC windings for use at cryogenic temperatures

The use of hyperconductors presents entirely new conditions in the design of transformer windings. Because of the very large mean free path of electrons, a few parasitic effects of resistivity can no longer be neglected: size effects determine the minimum thickness of the conductors, magnetoresistive effects are much less adverse with ac fields than with dc fields. As regards the low value of the penetration depth of electromagnetic waves, three types of aluminium windings with one single turn per layer have been studied: 1) Wide-Sheet Windings: The supplementary losses due to the radial field are high; their proportion is 340 percent in the example considered. 2) Transposed-Band Windings: The proportion of supplementary losses due to the radial field is reduced to 110 percent if the width of the strips is 0.4 mm. 3) Perfectly-Transposed Windings: An increase in length of the conductors must be accepted. This increase and the radial field result in additional losses of 90 percent for the same width of strips of 0.4 mm. If the geometry of the two windings and the ampere-turns are fixed, and if the lateral dimensions of the conductors remain the same, the losses pass to a minimum value for a value of the apparent resistivity which is a function of these dimensions. The total losses become 3.75 times smaller than those of the wide-sheet winding in reducing the lateral dimensions of the strips and in simultaneously choosing a metal of greater purity. This reduction in the dimensions is, however, limited by the size effect. Beryllium presents less difficult problems.

Note on the temperature compensation of precision dynamometer instruments

Small residual errors are found in precision dynamometer instruments, partly due to the resistance temperature coefficient of the copper and aluminium windings, but more particularly owing to the self-heating effect of the current in the windings on the control springs. This article gives an account of the errors found in some instruments of this type, and the method of compensating them.

Aluminum windings for the field magnets of traction motors

Aluminum windings for the field magnets of traction motors