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The calculation of a transformer's parasitics, such as its self capacitance, is fundamental for predicting the frequency behavior of the device, reducing this capacitance value and moreover for more advanced aims of capacitance integration and cancellation. This paper presents a comprehensive procedure for calculating all contributions to the self-capacitance of high-voltage transformers and provides a detailed analysis of the problem, based on a physical approach. The advantages of the analytical formulation of the problem rather than a finite element method analysis are discussed. The approach and formulas presented in this paper can also be used for other wound components rather than just step-up transformers. Finally, analytical and experimental results are presented for three different high-voltage transformer architectures.

The detailed switch-level models of front-end diode recti fi er loads can be readily implemented using a number of transient simulation programs, such as PSCAD/EMTDC, and the toolboxes in Matlab/Simulink. To improve the simulation ef fi ciency for the system-level studies, the so-called dynamic ave rage models have been widely used by researchers and en- gineers. Recently, several aver age-value modeling methodologies for the conventional three-phase (six-pulse) front-end recti fi er loads have been discussed, and the dynamic performance of sev- eral developed models has been demonstrated in discontinuous and continuous modes. In this paper, the effects of topological variations of the ac-side fi lters on the system performance are investigated. Also, the steady-st ate and dynamic impedances pre- dicted by the average models under balanced and unbalanced operation are compared. The studies and analyses presented here extend and complement those set forth in the preceding companion publication.

In this paper, a thermally actuated medical stent and staple using shape memory alloy (SMA) are designed, numerically analysed, and compared to similarly designed stents and staples made of 316L stainless steel and Co-Cr alloy. The numerical analysis was carried out using finite element method. A consistent 3D model is used to investigate the effect of materials on the performance of the stent and staple. This study takes into account the interaction between the stent/staple and the in vivo environment, by modelling the in vivo environment forces. The results are in good agreement with those reported in the literature. According to the results, it can be concluded that when these three commercially available materials undergo an external force, SMA yields much better results in terms of maximum displacement under the same amount of stress. Especially when undergoing large loads, the SMA produces considerably more displacement than 316L stainless steel and Co-Cr, which suggests that using SMA is a promising path to make biomedical stents and staples.

This paper presents an experimental investigation on vibration control using an active mount activated by piezostack actuators. After describing the schematic configuration and operational principle of the proposed active mount, dynamic characteristics of the rubber element and the piezostack are experimentally identified. An active mount is then manufactured using a rubber element and two piezostack elements. Prior to validating vibration control of the proposed active mount, fundamental characteristics such as resonant frequency, deflection at rated load, strength, shock and fatigue characteristics are experimentally investigated. A two-degree-of-freedom control system in which an active mount is installed with a supported mass of 100 kg is established for evaluating vibration control performance. In order to actively attenuate the vibration transmitted from the base excitation (50–1000 Hz), a negative velocity feedback controller is experimentally realized. Control responses such as mass acceleration are evaluated in both frequency and time domains.

Wireless sensor networks (WSNs) have gained importance in recent years as this support a large spectrum of applications such as automotive, health, military, environmental, home and office. Various algorithms have been proposed for making this technology more adaptive the existing algorithms address issues such as safety, security, power consumption, lifetime and localization. This paper presents an extension to HiRLoc algorithm and highlights its benefits. Extended HiRLoc significantly reduce the average localization error by suggesting a new method directional antenna based scheme.

Multistatic radar has attracted considerable interest. One of the reasons is that it can provide improved performance against deception jamming. However, the existing anti-jamming methods always need multiple pulse repetition intervals (PRIs), and the slow fluctuating targets will be misjudged as deception targets. In this paper, hierarchical clustering analysis method is first utilized in multistatic radar to discriminate deception targets within one PRI in a defined amplitude ratio feature space, in which deception targets concentrate on one position, while physical targets possess dispersion characteristic. Two approaches are provided to terminate the clustering process by optimizing the number of clusters or designing the minimum cost among clusters. The first one works in most cases without any prior information, but is not in Neyman–Pearson sense. The other one can achieve a constant probability of false alarm, but obtain its optimal performance only when the jamming-to-noise ratios of all generated false targets are approximately equal. According to the final clustering results, deception targets can be discriminated by deciding that the targets in the cluster with more than one target are all false targets. The simulated results are covered to illustrate the feasibility and validness of the proposed approach.

Motor current signature analysis is the reference method for the diagnosis of induction machines. However, it features some drawbacks, as it is bound to steady-state conditions, and fault signatures may be created by different overlapping phenomena. This paper presents a full-time domain-based method for the quantitative evaluation of electrical faults in induction machines. It relies on stator current measurements; thus, it is compliant with switching power converter drives, provided that a proper current measurement technique is available. Moreover, it allows an accurate quantification of faults without requiring spectrum analysis; hence, it achieves high resolution even with a low time acquisition period. A fault index is computed as the energy of the signal in a suitable ldquofault bandwidth,rdquo thus reducing the effects of frequency variations. The aforementioned advantages are perfectly suited to time varying signals and to embedded drive diagnostic systems.

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An extension of the Potier method of testing for armature leakage reactance of synchronous machines is presented in this paper, wherein it is shown that the easily tested for Potier reactance varies considerably and therefore has a limited field of usefulness. It is further shown that if the Potier reactance is measured at high values of field current, the armature leakage reactance is closely approximated and a more valuable test results.

The paper deals with simulations of power line channel transfer functions in Network Simulator version 3. Firstly, an empirical model and calculation of the channel transfer function are given to reflect the necessity of channel transfer function for Power Line Communication system design. The framework for Power Line Communication in Network Simulator version 3 and then the necessary extension implementation are introduced. Other simulators are also mentioned. Secondly, various scenarios were implemented for the analysis and simulation of power line channel transfer functions. New scenarios for large topologies and for different approaches to calculate primary parameters were created. In the simulations, various kinds of topologies are considered for an analysis of the power line transfer function. The simulation part also focuses on the simulation of channel transfer function where the time- and frequency-selective impedances are considered. Finally, the last part focuses on measurements and a comparison of the simulation results with real measurements are given.

A methodis given in this paper for determining the wave forms of alternating currents which uses no highly specialized measuring apparatus. No contact maker is used, and it is generally appliable on polyphase circuits only. It is recommended as a method which may be used under many circumstances where the special contact maker apparatus is not available.

For a number of years, two-axis Sawyer motors have been used as motive devices for flatbed plotters and wafer probers. These two applications are quite different in their requirements for motor dynamics, but both depend on the motor's high speed and good open-loop positioning capability, as well as on its almost unlimited life expectancy. The motors are now being applied to a variety of other motion system requirements, and motor and control drive electronics tailored to these more general applications are being produced. This paper presents some general properties of the motors and describes the control strategies utilized to maximize their performance.

The UHF FLEETSATCOM system provides a substantial resource to support important communication needs of the U.S. Navy and other Department of Defense users. Because of the significant investment being made in this system, there is strong motivation to examine techniques that make efficient usage of its components. This paper reports on one such effort, the Terminal Access Control System (TACS) that was developed at the M.I.T. Lincoln Laboratory. TACS utilizes time division multiple access (TDMA) to derive up to nine 2400 bit/s circuits from each of the several 25-kHz-wide frequency channels available on the FLEETSAT satellites. Using TACS, access to these circuits would be controlled in real time by a central control station in response to user demand. This application of demand assignment further multiplies the number of subscribers that can use the system by a significant factor. A description of the access control techniques and efficiency of performance is provided. A master control station and subscriber unit were constructed and used in an extensive laboratory test program.

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The author of this paper has endeavored to exemplify certain fundamental principles connected with the phenomena upon which he has treated; and in considering these subjects, all of which may be said to be on the borderland of science, to bring out means of experiments, lantern slides and illustrations which accompany the paper, the practical and commercial side. He entertains the hope that the matter herewith submitted will prove of interest to the members of the societies before whom he has the honor of appearing, and may serve in some slight degree to stimulate investigations in these most promising fields.

The presentation of this paper has been undertaken with a view to supplying the Committee on Standardization with data to enable them to draw up rules for the determination of voltage regulation, as Section 71 of the INSTITUTE rules is, no means, in accordance with fact and observation.

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Comments by F.O. Blackwell, H.A. Lardner, and B.J. Arnold. The Redlands plant is the first three-phase power transmission plant in the United States. It had at first two 250 k.w. 2500 volt generators, operated by wheels under a 300 foot head, alnd a seven mile transmission; synchronous motors were used. Later, ahead of 800 feet was developed, and two 450 k.w. 11,000 volt machines were operated on a 30-mile transruission. This plant was connected in parallel with the Santa Ana plant, which supplied a transmission line 90 miles long to Los Angeles. The plant described in the pnaper operates under a head cf 2,000 feet and has a capacity of 4,000 hp, using the same water as the former plant. The generators are of low-voltage, tlle line pressure is 33,000 volts, and feeds into the same transmission lines to Los Angeles. The Los Angeles Edison Company controls seven power stations, located at points as far apart as 100 miles - all feeding the same transmission system, and operating practically as one station; they are now developing a new plant on the Kern River, of a capacity of 20,000 h.p. to operate at 60,000 vclts and transmuit 150 miles to Los Angeles. Thus the history of this system embodies the entire development cf hydro-electric transmission in this country.

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The object of this paper is to invite discussion on what seems to be the more important features of instrument engineering, and its value to the Institute should be found in the discussion rather than in the paper itself.

The usefulness of a satisfactory method of observing or recording the wave forms of rapidly varying electric currents and pressures has been appreciated almost from the time that investigators and designers commenced working with electrical apparatus. The various methods which have been used for obtaining these records or indications have had, and are having, an important influence on the design of apparatus and a clearer understanding of the phenomena accompanying their use. It is the purpose of this paper to outline briefly the steps which have led up to the methods in use at the present time, and to describe more fully the devices which are now most employed and the uses to which they may be put.

The purpose of this paper is to present a system of design, not based upon the cut-and-try method associated with the use of an output constant, but directly upon general experimental data and the commercial guarantees of the machine; and to deal with the limitations imposed upon the development of large machines by the quality of brushes obtainable.

In the following pages it is proposed to discuss some of the elementary phenomena found while studying the performance of alternators excited by alternating currents. In a second paper the writer intends to deal with the practical application of the principles here described.

The question of the proper reserve in an electrical installation is a problem that, like many engineering problems, must be settled largely upon a basis of cost. It is nearly always a question involving a balance between a power company's obligation to its customers and the obligation to its stockholders. From the standpoint of the consumer the more reserve the surer will be his supply of power. On the other hand, to the power company's stockholders the less the investment in reserve the larger the dividends, unless the reserve has been cut down to a point where the power company's reputation is endangered by interruptions to service. The question is purely a practical one and no definite laws can be enunciated, nor can any curves be plotted which will indicate the proper amount of reserve to be installed under various conditions. The decision in each case must be based on intimate knowledge of the local conditions and requirements of the particular installation in question. All that will be attempted in this paper will be a discussion of the general principles involved.

In a paper read before the American Institute of Electrical Engineers in December, 1898, the author advanced the hypothesis that the injury done by sparking at the brushes of a direct-current dynamo was not due, as was then commonly supposed, to the current jumping across the gap between the segment and the brush, but was done while the brush was in contact with the segment, the copper of the segment being first melted and then volatilized by the concentration of current energy at one or the other of the segment edges. Perfect commutation was also defined as such a change in the current in the coil under commutation that the current density over the contact surface between the brush and the segment would be constant and uniform, and that perfect commutation would result if the coil impedance were negligible as compared with the brush contact resistance. It was also shown that with perfect commutation the total energy developed over the contact surface would be a minimum and that every part of the contact surface would receive an equal amount of energy. On this principle the question of sparking is simply a question of the temperature of the segment while it is under the brush.

In a locomotive propelled by electric motors the motor action produces a set of stresses acting between the truck-frame, motor supports, and driving-wheels. The horizontal effort at the rail-head resulting from these stresses acts against the resisting forces of the locomotive, the principal items of which may be considered as: a. The rolling friction of the wheels on the track, acting at the rail-head. b. The resistance to acceleration due to inertia of the locomotive, and the resistance due to grades, acting at the center of gravity of the locomotive. c. The air resistance, acting at the exposed surface particularly at the head end. d. The resistance of the trailing load, acting at the draw-bar. The effect of the forces here discussed including the internal or driving forces acting between truck, motor, and wheels, and the external or resisting forces, produces a shifting or redistribution of the weight on the various wheels. In the following paper the attempt has been made to investigate the amount of this redistribution. The discussion is limited particularly to locomotives drawing trailing loads, since this redistribution of weight is particularly effective in the case of a locomotive exerting a horizontal effort at approximately the slipping point of the driving-wheels. Some of the general limitations and considerations applying to this particular case must be clearly defined.

In this paper the phrase “synchronous motor-generator” means an alternating-current synchronous motor directly connected to an alternating-current generator. The author's intention is to point out some of the details of construction, connections, and method of operation that need to be considered in order that a desired division of load will result when such units are operated in parallel.

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In this paper will be related the actions of the multigap series resistance type of arrester unit, and the multigap type of arrester unit without the series resistance, experienced during the years 1904 and 1905 on a 33 000-volt transmission system operated by the New Milford Power Company, of New Milford, Connecticut.

The division and arrangement of units and the system of electrical connections in a power station have much to do with the cost and successful operation of the plant. Conditions vary to an extent which prohibits the use of standard arrangements, but certain general principles are applicable to all layouts. For the purpose of this paper the factors to be considered are generators, transformers, lines, bus-bars, and switches with their relays. The kind of load, number of stations on system, lines in parallel, number of lines, size of generator and transformer units, and local conditions, govern the power house arrangements.

In this paper, we present the fabrication and test results of an oxide-coated polysilicon disk resonator gyroscope in a wafer-scale encapsulation process. We demonstrate the effects of an oxide coating on the device structure and the key performance parameters of resonant-based sensors, such as the temperature coefficient of frequency and quality factor ( $Q$ ). Results from the as-fabricated device show that a thin oxide coating reduces the surface roughness of a fully encapsulated device by $10\times $ , compared with a polysilicon device without the oxide coating. This increases the uniformity across the wafer, providing higher process yield. The open-loop rate measurement mode reveals an angle random walk of 0.18°/ $\surd $ hr and a bias instability of 1.43°/hr. [2015-0124]

During the last few years there has been a gradually increasing tendency in this country toward the use of three-phase transformers on three-phase circuits instead of groups of three, or in some cases two, one-phase units. It is the purpose of this paper to outline briefly these two systems, and to point out as far as possible the important features of both, with their advantages and limitations.

For any given transmission line there is a certain length of span which is most economical. A determination of what the economical span is, in any case, can only be made by obtaining data showing the variation of each item of cost which changes with the length of span. In a steel-tower line the cost of the tower is probably the most important among those items which vary with the length of span. As the span is made longer, the towers must be made higher and stronger. The purpose of this paper is to describe a method by which the relation between the height, strength, and cost of a tower of given form may be expressed. The application of this method to the problem of fixing the economical span will also be shown.