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Industry Applications, IEEE Transactions on

Issue 4 • Date July-Aug. 1989

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Displaying Results 1 - 25 of 27
  • Series and parallel operation of hysteresis current-controlled PWM rectifiers

    Page(s): 644 - 651
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (542 KB)  

    Different strategies for series and parallel connections of hysteresis current-controlled PWM rectifier have been investigated by experiments, computer simulations, and analyses. Each rectifier unit delivers near-sinusoidal current waveforms at unity (or even leading) power factor. Of particular concern are the questions of: (i) system stability; (ii) the capability of the modular units to share voltage (series connection) and current (parallel connection) under steady-state and transient operation; and (iii) sensitivity of performance characteristics to component tolerances. Experiments were made on 1 kW bipolar transistor modular units. Two configurations, having independent local control (type A) and common switching control (type B), respectively, were studied. The study shows that type B is more economical than type A and appears to give a satisfactory performance.<> View full abstract»

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  • Electrostatic separators for insulating fluids

    Page(s): 728 - 731
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    Electrostatic separators have been used in purifying hydraulic fluids, fuels, petroleum refining and coal liquefaction streams, lubricating oils, and other insulating liquids. The designs, applications, and separation efficiencies of these separators are discussed. The separators are categorized as employing either spatially uniform or nonuniform electrical fields, or electrical fields in conjunction with other physical separation techniques. They require low inlet pressures, draw low current, and are resistant to plugging. They are rugged, allowing use in high-temperature and -pressure applications. Many designs allow continuous or semicontinuous operation. Electrostatic separators can separate particles of similar density, shape and size by differences in electrical properties View full abstract»

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  • Zero-switching-loss inverters for high-power applications

    Page(s): 634 - 643
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    The development of zero switching loss inverters has attracted much interest for industrial applications. Two topologies for realizing zero switching losses in high-power converters are proposed. The actively clamped resonant DC link inverter uses the concept of a lossless active clamp to restrict voltage stresses to only 1.3-1.5 supply voltage. For applications demanding substantially better spectral performance, the resonant pole inverter (RPI), also called the quasi-resonant current mode inverter, is proposed as a viable topology. Using only six devices rated at supply voltage, this circuit transfers the resonant components to the AC side of each phase and thus requires additional inductor and capacitor (LC) components. On the other hand, the RPI is capable of true pulsewidth modulation (PWM) operation at high frequency as opposed to discrete pulse modulation operation found in resonant DC link invertors View full abstract»

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  • The in-plane fields of infinite arrays of discrete charges

    Page(s): 738 - 742
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    The electric field characteristics of infinite arrays of discrete charges are useful as the limiting cases for finite arrays of charges. Various methods were examined to obtain the field intensity; simple summation by computer, using thousands of charges, proved quickest and best. The results are presented as curves for the component fields. In addition, some discussion of the magnitude and space phase angle of the fields is given. This was done for linear arrays of equal charges spaced equal distances apart. A similar array of charges alternating in sign is also considered, and three cases of surface arrays are discussed View full abstract»

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  • Characterization of an electrodynamic balance for suspending charged droplets

    Page(s): 711 - 719
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    The electrical characteristics of an electrodynamic balance used for suspending charged droplets were determined by constructing a computer model based on the charge simulation technique. This device is traditionally constructed with hyperbolically shaped endcaps and ring electrodes since an analytical solution exists for the electric field in this geometry. Using the charge simulation technique, other electrode shapes (some with observation portals) were evaluated for their effectiveness in suspending and stabilizing droplets. In this stability study, the motion of a droplet within the electrodynamic balance was evaluated using a numerical solution of the equations of motion for a droplet in the calculated electrodynamic force field. Four shape attributes were considered: electrode curvature; chamber size and geometry; and electrode extension. Three end cap curvatures were examined: flat, hyperbolic, and more steeply curved. Two principal findings are: (1) viewing ports should be embedded within an axially symmetric groove, in which case they do not affect the function of the balance; and (2) the voltage needed to balance a particle against gravity is a strong function of the chamber geometry View full abstract»

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  • Criteria for approval of mining equipment incorporating on-board switching of high-voltage circuits

    Page(s): 676 - 682
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    The US Mine Safety and Health Administration (MSHA) recently developed criteria to modify the current regulation prohibiting the on-board switching of high-voltage circuits (>1000 V AC). Extensive research conducted by the US Bureau of Mines and MSHA provided the basis for the development of safe and viable criteria. Under the provisions of Title 30 Code of Federal Regulations, Section 18.82, experimental permits were issued to high-voltage continuous miners and longwall systems incorporating this new technology. The information gathered from the operation of this equipment in the field along with industry concerns and recommendations were considered during the finalization of these criteria View full abstract»

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  • Investigation of alleged appliance electrocutions and fires caused by internally generated voltages

    Page(s): 664 - 668
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    Many appliances convert the supply sinusoidal voltage to another voltage or waveform. Evaluation of the possible electrocution and fire hazards, which is important for internally generated voltages such as a single pulse from a capacitor, trains of pulses, direct current, and high voltage alternating current, is reviewed. For electrocution studies, the effect of a periodic output waveform is related to an equivalent 60 Hz sinusoidal electrical shock. The lethal effect for shocks from voltages with periodic waveforms is determined by the frequency components on the human body. Electrical injury is related to the energy in the shock for single pulse shocks. For direct current shocks, approximately three times as much current is required for a given effect on the human body as for 60 Hz shocks. Appliance power supplies can be a source of ignition for fires when combustibles are present. High-voltage current-limited supplies can cause fires when output currents track across combustible surfaces or ignite combustible material between the electrodes View full abstract»

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  • Harmonic measurements using a digital storage oscilloscope

    Page(s): 783 - 788
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    It is pointed out that the availability of high-quality digital oscilloscopes at reasonable cost, which can be connected to the power system using current transformers and potential transformers to capture and digitize voltage and current waveforms, allow the plant engineer to make fast, accurate harmonic measurements on the plant power system. Microprocessors, often built into the oscilloscope, can quickly and easily analyze this digitized data. The need for harmonic field measurements, for equipment required, and the properties of the fast Fourier transform (FFT) algorithm are discussed View full abstract»

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  • Triangle-shaped DC corona discharge device for molecular decomposition

    Page(s): 743 - 749
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    An earlier point-to-plane geometry corona device with a rectangular cross section demonstrated low decomposition efficiencies. The numerical simulation of this device suggested that three were zones of low electron density and electric field significant decrease in resulting in electrical sneakage which caused a significant decrease in the kinetic rate coefficients in the chemical reaction process. A triangle-shaped DC corona discharge device was developed to improve the electrical sneakage problem, and a semiempirical mathematical model was developed to describe the detailed electrical characteristics and to refine estimates on the optimum shape of the device. The preliminary experimental results indicated that the decomposition efficiency was much improved View full abstract»

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  • Self-acceleration of a charged jet

    Page(s): 699 - 704
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    When insulators are sprayed electrostatically, charges are injected into the liquid, resulting in the formation of a charged jet. Mutual repulsion between these charges, which reside on the jet surface, causes the jet to accelerate. This acceleration is opposed by surface tension and inertial forces. As the jet accelerates, its radius decreases until it reaches a minimum radius. When the minimum jet size is achieved, the rate of acceleration decreases to zero. Equations are derived which allow this minimum radius to be calculated. In addition to the accelerating jet, the equations have another solution with the jet decelerating. In the experiments the acceleration is observed but not the deceleration. Rather, drops form on the end of the jet, indicating that it becomes unstable before it can decelerate. The values for minimum jet radius calculated from the equations are compared with experimental measurements of the minimum jet size in electrostatic spraying of insulators, and good correlation is obtained View full abstract»

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  • Drop size measurements in electrostatic paint sprays

    Page(s): 720 - 727
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    Drop-sizing experiments were performed on an electrostatic fan-spray atomizer operated in the airless mode. Tests were conducted with and without application of a high-voltage charge to the electrode tip placed downstream of the nozzle exit. A nonintrusive Malvern 2600 particle sizer, based on the forward scattering of a 5 mW He-Ne laser beam, was used to yield line-of-sight and cross-sectional drop size distributions. The atomizer was traversed across the laser beam, and drop size profiles as a function of distance from the centerline were developed. Enamel paint with a viscosity of 17 cp was sprayed over a differential pressure range of 1.38 to 6.20 MPa. Results indicate that at low injection pressures the charge application has a significant effect on the average drop size and the spatial drop distribution. However, as injection pressure is increased, the electrostatic influence on drop size and distribution decreases View full abstract»

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  • A starting inverter for a voltage-source series inverter with a transformer-coupled high-Q induction heating load (type A inverter)

    Page(s): 627 - 633
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    The voltage-source series inverter with a transformer-coupled high-Q induction heating load is found to have latching and commutation problems at starting due to insufficient output current. This is because a high-Q load requires a number of cycles before sufficient energy, and therefore current is built up in the series load. A novel starting inverter is presented which establishes sufficient current in the load at starting. The operation of the inverter is described, and the modes of operation are identified. The behavior of the inverter in each mode is analyzed, and an optimum mode is selected which results in the minimum rating of the starting inverter. The selection and the rating of the components to design the starting inverter are presented. A prototype inverter system has been built and all theoretical results have been verified experimentally View full abstract»

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  • Computer-based monitoring and remote control of a new highwall mining system

    Page(s): 683 - 690
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    A new highwall mining system (HMS) for coal extraction in unreclaimed and active contour strip mines has been developed. The system is comprised of a computer-based remotely controlled thin-seam continuous miner, a multiple-unit continuous haulage system, and other support equipment located on the highwall bench. The mining process is controlled remotely by a single operator from a protected, ergonomically designed workstation. The HMS offers safe economical mining of unreclaimed coal resources. It has the potential to be competitive with other highwall coal extraction techniques, with a productivity goal of 22 ton/man-hour. Surface tests of the miner and haulage systems were completed at the US Bureau of Mines test facility. Specific results from these tests are included. Field protection trials of the HMS are being conducted View full abstract»

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  • Analysis and design of a three-phase synchronous solid-state VAr compensator

    Page(s): 598 - 608
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    A three-phase synchronous solid-state VAr compensator (SSVC) system that uses a three-phase pulsewidth-modulated (PWM) voltage-source inverter is presented and analyzed. The proposed SSVC system can compensate for leading and lagging displacement power factor. Pulsewidth modulation is used as a means of reducing the size of reactive components. The SSVC system is analyzed under self- and independently-controlled DC bus voltage operating conditions. Other areas of investigation include the design of SSVC filter components for both approaches and the closing of the loop around the reactive power command signal. Predicted results are verified experimentally for the case of the SSVC working with a self-controlled DC bus View full abstract»

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  • Drop-on-demand operation of continuous jets using EHD techniques

    Page(s): 705 - 710
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    In some applications of continuous jet drop generators, it is helpful to produce a single isolated drop instead of the stream of drops normally encountered. A voltage pulse applied to a nearby electrode can produce an isolated drop, but only if the size and shape of the pulse are carefully chosen. The proper choice is determined by decomposing the input voltage into Fourier components, following each one along the jet, and then recombining them to give a snapshot of the jet at the breakoff point. A computer program has been developed that produces a graphical profile of the jet response that demonstrates how the jet would appear in actual operation. Visual inspection of the calculated jet profile while adjusting the pulse parameters leads to several suitable voltage pulses for drop-on-demand operation View full abstract»

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  • Novel method of cell fusion in field constriction area in fluid integration circuit

    Page(s): 732 - 737
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    A novel method of cell fusion is developed based on the fluid integrated circuit (FIC) concept, in which all cell-handling components are photolithographically integrated on the substrate. A strong field constriction area is produced between the cell fusion electrodes by constricting all electric fluxes to a small opening made at the center of an insulating barrier placed between the electrodes. Cells are sent, one by one, from two micropumps, each containing a suspension of one type of cells, and then dielectrophoretically trapped at the opening to form a pearl-chain pair. Then the pulse voltage is applied to trigger the fusion of the cell pair. This procedure ensures that the fusion product is an exclusive one-to-one hybrid among the two species. Problems associated with the adhesion of the fusion product on the electrodes do not arise. The small dimensions of the field constriction area allow the application of constant pulse voltage on the cell membranes, regardless of the cell diameter. The FIC cell fusion device has been constructed and its performance tested. Analysis of the field constriction area is also made View full abstract»

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  • Industrial and cogeneration protection problems requiring simulation

    Page(s): 766 - 775
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (836 KB)  

    The procedures outlined in relay instruction manuals for setting out-of-step, loss-of-excitation, reverse power, external fault, and similar protective relays cover typical situations and may not be appropriate in all circumstances. Cogenerators, small power producers, and industrial generators can face long fault clearing times, high fault levels, lower fault levels, high voltage, and a range of other unusual conditions in the adjoining utility system. Some critical relay applications and the simulations required to select the best settings are outlined for use in such cases. The discussion covers out-of-step protection; loss-of-excitation protection; reverse power protection; overcurrent protection; shaft torques from utility reclosing; load shedding; and self-excitation overvoltages View full abstract»

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  • Development of an expert system for diagnosing component-level failures in a shuttle car

    Page(s): 691 - 698
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    The development of a rule-based expert system (referred to as SCAR) for assisting electricians in diagnosing electrical faults in a shuttle car is discussed. Insight 2+, a microcomputer-based expert-system development tool by Level Five Research, Inc. was used in creating the system. The program requires the user to specify the initial symptoms of the failed machine; then the most probable cause of failure is traced through the knowledge base, with the software requesting additional information, such as voltage or resistance measurements, as needed. A causal-reasoning approach, which was used to develop the production rules, is described. The organization, implementation, and limitations of the knowledge base are also presented, along with a brief discussion of the ongoing development of a new system, SCAR.2 View full abstract»

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  • An adaptive seam tracker for welding heavy-section aluminum

    Page(s): 658 - 663
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    Robotic welding systems which cannot adapt in real time to changes in the joint geometry along the weld seam and to the seam position itself have only limited success in many welding applications, due to heat distortion of the weldment or to an overall shift in the weld seam caused by fixturing errors. A solution to this problem requires the application of some form of adaptive joint geometry sensing system for guidance of the welding torch. Research is described that addresses the general aluminum welding problem by integrating a laser-based part-profiling sensor with a welding robot. An adaptive system is being developed that is referred to as ARTIST (Adaptive Real-Time Intelligent Seam Tracker). An IBM PC/AT-compatible microcomputer serves as the system supervisor, commands the motion of the robot, directs and processes the sensor scans, and establishes the required weld parameters. The programming language used in the microcomputers is C, chosen primarily for its flexibility and high execution speed. The host robot is a Unimate 760 Series electric six-axis articulated arm, using a VAL II controller View full abstract»

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  • Commutated relay switching system

    Page(s): 669 - 674
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    A basic electronic control scheme which allows relays to be utilized at fast switching rates with long lifetimes and is applicable with standard microprocessor-based systems is described. The basic power-switching circuit consists of a commutating diode connected in parallel with the contacts of a single master relay, and this combination connected in series with a parallel combination of slave switching relays and associated loads. Timing and control is provided in such a way that the relays are switched at a high frequency but never with current flowing through the contacts. An actual range application with multiple loads is described, along with the necessary circuitry and logic. In addition, a diagnostic scheme is described which takes advantage of the commutated system to determine component failures in the power switching loads View full abstract»

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  • Modeling and implementation of a microprocessor-based CSI-fed induction motor drive using field-oriented control

    Page(s): 588 - 597
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    A new approach to model the current-source-inverter-fed induction motor drive is presented. The mathematical model takes into account the rectifier, inverter, and induction motor dynamics and is established in the stationary reference frame. For controlling the drive speed, a modified indirect field-oriented control is proposed. To counter the effects of torque pulsations at very low speeds and rotor resistance variation, a slip compensation loop is included in the control law formulation. A microprocessor-based prototype system is also implemented, providing full digital control of the drive speed. Both computer simulation and experimental results are presented View full abstract»

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  • A nondissipative snubber circuit for high-power GTO inverters

    Page(s): 620 - 626
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    A novel snubber circuit for high-power GTO inverters is composed of only passive components which, idealized, produce no losses. The stored energy in the turn-on and turn-off snubbers is completely recovered during a switching cycle. In the absence of a permanent circulating current in the recovery transformer, the minimum on-time duration of one half-bridge is very low. The nondissipative operation of the snubber circuit permits a liberal design of the snubber components by which the switching losses in the power semiconductors are greatly reduced View full abstract»

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  • Analysis and design of a novel 3-φ solid-state power factor compensator and harmonic suppressor system

    Page(s): 609 - 619
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    A novel three-phase solid-state power factor compensation scheme is presented and analyzed. This scheme employs a PWM voltage-source inverter and has two important features. First, it can maintain a near-unity mains input power factor without sensing and computing the associated reactive power component, and second, it can substantially reduce any line current harmonics generated by nonlinear types of load. The proposed scheme is discussed in terms of principles of operation, power system design, and analysis under unbalanced operating conditions. Predicted results are verified experimentally View full abstract»

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  • Electrical studies for an industrial gas turbine cogeneration facility

    Page(s): 750 - 765
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    Electrical studies are required to assure the proper integration of a gas-turbine cogeneration facility into an existing industrial-plant electrical system and the connected utility grid. Details of such a study are presented, including boundary-limit definition for the system model, individual component modeling, load-flow and short-circuit studies, stability studies, and simulation of online isolation from the electric utility during system undervoltage or underfrequency conditions. The impact of such studies on the design process and plant system reliability is discussed View full abstract»

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  • Compact laser-diode sources for optical inspection probes

    Page(s): 652 - 657
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    The use of laser diode sources rather than conventional tube lasers to provide the illumination for many optical probe applications is considered. The technical issues addressed include temperature control, output intensity control, and collimation of the light output. Possible solutions, as well as experimental results from a laboratory optical probe developed using a laser diode source, are presented View full abstract»

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Aims & Scope

The scope of the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS includes all scope items of the IEEE Industry Applications Society, that is, the advancement of the theory and practice of electrical and electronic engineering in the development, design, manufacture, and application of electrical systems, apparatus, devices, and controls to the processes and equipment of industry and commerce; the promotion of safe, reliable, and economic installations; industry leadership in energy conservation and environmental, health, and safety issues; the creation of voluntary engineering standards and recommended practices; and the professional development of its membership.

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Carlton E. Speck