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Industry Applications, IEEE Transactions on

Issue 3 • Date May/Jun 1988

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Displaying Results 1 - 25 of 25
  • Voltages to ground in load-commutated inverters

    Page(s): 526 - 530
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    Load-commutated inverter (LCI) drives are well suited to the starting and variable-speed operation of large fans, pumps, and compressors used in the petroleum industry. The origin and magnitude of the voltages to ground found in these types of drives are introduced and explained. The voltage to ground in most of the LCI circuit depends on bridge firing angles and can reach a maximum value as high as 2.4 p.u. (per unit) of rated. An analysis of this phenomenon and an algorithm for predicting the magnitude of the voltage as a function of machine voltage, and bridge firing angles is presented. Test results are included for validation of the analysis. How system grounding and DC link reactance can be used to reduce the magnitude of the elevated voltage to ground and transfer it to less devices is discussed View full abstract»

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  • Protection of thyristors against overvoltage with breakover diodes

    Page(s): 444 - 448
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    Overvoltage protection is achieved by connecting the breakover diode (BOD) between anode and gate of a thyristor in such a way that it is turned on when excessive voltage occurs. The turn-on delay time of the thyristor is dependent on the magnitude of the supplied BOD current. The delay time can be less than 0.3 μs, so that protection against steep transient is possible. The BOD is, in many cases, indispensable for thyristor strings when the load conditions are unpredictable View full abstract»

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  • A microcomputer-based speed controller for lift drives

    Page(s): 487 - 498
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    A microcomputer-based speed controller for squirrel-cage induction motors for lift drives is presented, designed as a replacement for the classical analog versions. The appropriate speed control is achieved by phase-cut stator voltage control and by dynamic braking with DC current injection. Both actions are implemented by standard analog phase-control integrated circuits and 8-bit D/A (digital-to-analog) converters. A speed feedback signal is generated by a noisy tachogenerator, so that a low-pass antialiasing filter, followed by a true-averager circuit, is involved for proper signal conditioning. The true averager provides high rejection of the mains frequency and its higher harmonics. The built-in self-test routines and associated circuitry provide part-by-part testing of the hardware. This together with simple diagnosis, supports faster installation and more efficient troubleshooting. Complete firmware is organized in the shape of interrupt-driven routines, which are reentered at every mains zero crossing in the positive direction. A reference-speed profile with the shape of parabola is used to achieve a constant acceleration-time gradient. A discrete proportional integral (PI) control algorithm with lag-lead frequency compensation gives acceptable control accuracy, stability and robustness View full abstract»

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  • Mechanics of bearing systems

    Page(s): 531 - 540
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    The mechanics underlying the performance characteristics of fluid-film bearings are discussed with emphasis on the dynamic properties of bearings. Advantages and disadvantages of different bearing geometries are described. Different methods of oil supply are discussed. The characteristics of an innovative bearing configuration, called the hybrid bearing are described View full abstract»

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  • The generalized theory of indirect vector control for AC machines

    Page(s): 470 - 478
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    The instantaneous torque produced by an AC machine is controllable when vector control is applied. However, the published papers on vector control deal with either induction machines or synchronous machines. A generalized vector-control theory is developed, considering a generalized AC machine as a salient-pole synchronous machine having three kinds of torque, i.e., the field torque, the reluctance torque, and the induction torque. The theory can be extended to the AC machines producing a voluntarily combined torque among the three. The experimental system consisted of applying the generalized vector control theory to a nonsalient-pole synchronous machine with damper winding. It was verified experimentally that the instantaneous torque was controllable, not only in synchronous or induction-machine operation, but also in the transient state between the synchronous-machine operation and induction-machine operation, without any change of the control circuit View full abstract»

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  • Modeling of large AC motor coils for steep-fronted surge studies

    Page(s): 422 - 426
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    Interturn insulation failure is now recognized as a common cause of failure in large AC machines. The line-end coil is the most likely site of such failure, since under steep-fronted surge conditions it bears 100% of the surge amplitude for several microseconds. During this period, measurements show that the interturn voltage distribution in the line-end coil is nonlinear, with up to 40% of the surge voltage appearing between the last two turns of the coil. To predict the voltage distribution in the line-end coil under such conditions, a multiconductor transmission line model of the coil has been developed. This model can then be used in a general-purpose electromagnetic transients program (EMPT) or in a special-purpose EMPT. Results are presented for measured and simulated waveforms on a large AC motor. The simulations have been done on a special- purpose EMPT. The latter has also been used to compute the impulse response of the coil which can, then be convolved with the applied surge waveforms to derive the coils response to a variety of surge waveshapes. This is a much cheaper method of solution if responses to a variety of surge waveforms are required since it only requires running the PT program once, followed by a number of runs of the much simpler and faster convolution program View full abstract»

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  • Nonlinear modeling of transformers

    Page(s): 434 - 438
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    The performance of classical transformer models under nonsinusoidal excitation is investigated and two novel models for such analysis, both of which account for the transformer core magnetic nonlinearities, are presented. All analytical results are compared with experimental data View full abstract»

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  • Destruction of living cells by pulsed high-voltage application

    Page(s): 387 - 394
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    Destruction of living cells in liquid has been formed by pulsed high-voltage application to the liquid. S. cerevsaie (yeast cell) or Bacillus natto, dispersed in deionized water and one- and three-percent NaCl solution, were used in this experiment. Four different electrodes (plate-plate, needle-plate wire-cylinder, and rod-rod electrode) were tested. The survival rate of cells was measured against peak electric field Ep pulsewidth T W, and pulse application number N. The experimental results indicate that the survivability roughly follows Weilbull distribution. Yeast cells dispersed in deionized water could be almost completely destroyed when the wire-cylinder electrode was used with Ep=20 kV/cm, TW=100 μs, and N=200. The energy input to a unit volume of the liquid to complete the cell destruction, however, differed significantly with the electrode type. The wire-cylinder electrode required above 10-30 cal/cm 3 to destroy the yeast cell in deionized water to 10-6 survivability. This value was less than that required more than 70 cal/cm3. Using the rod-rod electrode contained in a pressure vessel, an arc discharge was generated to produce an intensive shock wave, which also destroyed the cells by its mechanical force. In this case, 5-10 cal/cm3 of energy was required to decrease the survivability of yeast cells in deionized water to 10-6. Though further studies are necessary, this results indicate a possibility of the cell destruction by pulsed high voltage to be used as an energy-efficient sterilization process View full abstract»

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  • A high-performance cross-current type cycloconverter-fed induction motor drive system

    Page(s): 479 - 486
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    Making use of the latest techniques, the authors have successfully developed a cross-current-type cycloconverter-fed, squirrel-cage induction motor drive system, which far exceeds DC drive systems over a wide range from zero speed to high speed. It is best suited for tandem cold mill main and various other large-scale rolling mills View full abstract»

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  • A new sensing device for washing machines

    Page(s): 499 - 502
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    A device is presented that is able to monitor the washing process, turning the washing machine into a closed-loop controlled machine. The device, based on light scattering to detect the different structure of surfactant micelles and emulsions, is able to understand the different situations occurring during the washing and determines when it is over. This creates savings of electric power, detergent, and water View full abstract»

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  • Numerical computation of fields in electrostatic devices: experience and applications

    Page(s): 395 - 401
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    A computer package developed for the numerical field computation of electrostatic fields is presented. The package is composed of an interactive preprocessor for data definition, a field computation program based on the general purpose field computation code COMPELL, and a program for the interactive analysis of results and postprocessing. It has been devised to simplify as far as possible its management by users not skilled in numerical methods and is provided with a quasiautomatic grid-generation algorithm and a powerful data definition system for advanced users. The package has been field proven with good results on many practical cases, both of scientific and technical interest, and some obtained results are shown and discussed View full abstract»

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  • Design optimization of glass-embedded capacitive-type water sensors

    Page(s): 402 - 410
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    Capacitors consisting of oppositely charged inductor bars sandwiched between two parallel plates of glass are well suited for applications requiring the detection of water. The sensitivity to water on the glass surface is a complication function of both the geometry and dielectric properties of the sensor and its environment. A closed-form analytical model suitable for use in the optimization of such sensors is presented. The model is successfully applied to the design optimization of an example and is verified using a finite-different model and test results View full abstract»

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  • An efficiency-optimizing permanent-magnet synchronous motor drive

    Page(s): 462 - 469
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    A permanent magnet synchronous-motor drive that uses and adaptive control to find the maximum-efficiency operating point at any speed and load is demonstrated. Active damping is provided by modulating the inverter frequency in proportion to the perturbations in the average inverter DC link current. All principal control functions, including efficiency optimization and frequency modulation, are performed by a real-time digital control algorithm, using only the filtered inverter DC link current as a feedback signal from the inverter. Laboratory tests and computer simulations demonstrate the performance of the efficiency-optimizing control and the frequency-modulation feedback loop View full abstract»

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  • Maximum insulation stresses under transient voltages in the HV barrel-type winding of distribution and power transformers

    Page(s): 427 - 433
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    Analytical as well as experimental results are presented for voltages developed in HV (high-voltage) windings of dry-tyre power and distribution transformers when subjected to surge transients. Although the existence of this phenomenon has been known for years, it has not always been taken into consideration in the calculation of insulation stresses. The possibility of accurate prediction of the developed voltages is demonstrated View full abstract»

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  • Computation methods for one-dimensional bipolar charge injection

    Page(s): 411 - 421
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    Kerr electrooptic field-mapping measurements have shown strong space charge effects in high-voltage stressed dielectrics, where the magnitude and sign of injected charge depends on electrode material. With appropriate choice of electrode material combinations and voltage polarity is possible to have uncharged, unipolar positively or negatively charged, or bipolar charged dielectrics. The bipolar homocharge case lowers the electric field at both electrodes due to space-charge shielding, and thus allows a higher voltage without breakdown. Using charge-transport analysis the authors consider the general case of charge injection from both electrodes and solve time and space dependences of the electric field and charge distributions and the time dependences of the terminal voltage and current. This analysis extends earlier work by including nonequilibrium charge dissociation and recombination so that the effective ohmic conductivity is not constant but varies with time and position due to local net charge density. Specific cases discussed are the open-circuit voltage decay of an initially charged capacitor, the charging and discharging by a Marx generator, and alternating voltage excitations View full abstract»

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  • Design procedure for switched-reluctance motors

    Page(s): 456 - 461
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    Some of the design aspects of the switched-reluctance motor for nonservo applications are considered. Towards this objective, a step-by-step procedure is developed for the design of switched-reluctance motors View full abstract»

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  • The effects of fixture type and HVAC integration on fluorescent lamp/ballast performance

    Page(s): 365 - 369
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    The effects of fixture type and lamp compartment air extract on lamp/ballast performance are described. A luminate/plenum/HVAC simulator was used to measure minimum lamp-wall temperature inside four fixture types while varying lamp-compartment extract conditions. Experimental data show that the lumen output of the lamp/ballast system varies by 20% and system efficacy by 10% depending on the type of fixture and lamp-compartment extract technique used View full abstract»

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  • Electrostatic beneficiation of gold ores

    Page(s): 380 - 386
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    The authors present encouraging results obtained in separation of the Doyon gold ores when using the electrostatic inverted roof apparatus described by I.I. Inculer et al. (ibid., vol.IA-9, no.3, p.318-23, 1983). The electrification phenomena through combined tribo-electric and inductive charging were studied at various relative humidities. Contrary to expectations, the experimental work showed that the best separations are achieved at relatively high humidities of ~70% or higher. One of the main cost factors in electrostatic beneficiation of minerals is that of drying the material. The lesser drying required of this gold ore may be of considerable economic importance View full abstract»

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  • Saving electricity in commercial buildings with adjustable-speed drives

    Page(s): 439 - 443
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    Fan and chiller energy savings achievable in commercial buildings with adjustable-speed drives are described. The savings are estimated with the aid of parametric simulations from a sophisticated, hourly building-energy simulation model. Two prototypes-a single-zone retail store and a multizone medium-sized office building-are simulated for five US locations. The model incorporates part-load performance curves for both inlet vane and adjustable-speed drive controls for fans and centrifugal chillers. The results identify economic conditions that justify the added expense of adjustable-speed drives View full abstract»

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  • Analysis of three-phase AC-DC converters under unbalanced supply conditions

    Page(s): 449 - 455
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    A three-phase AC-DC converter is analyzed, and the performance of the converter under balanced conditions is evaluated. It has been observed that the level of unbalance plays a significant part in the converter characteristics, especially at the lower output voltage range View full abstract»

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  • Economics of switching fluorescent lamps

    Page(s): 370 - 379
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    Based on side-by-side cost comparison of different switching options, including a combination of parameters based against frequent switching, it is argued that it is economical to turn fluorescent lamps off when they are not needed. Background information to explain the calculation procedures and a sensitivity analysis are included View full abstract»

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  • Ground grid design in large industrial plants

    Page(s): 521 - 525
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    IEEE Standard 80-1976 is primarily concerned with ground gradient of substation installations. Large industrial petrochemical plants demand bulk power supply from substations and, coupled with cogeneration plants, make the design of the grounding system rather complex and costly due to high ground fault currents. The basic design criteria in grounding are clarified and a step-by-step procedure in designing a safe and economical ground grid for such plants is provided View full abstract»

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  • Power line carrier systems for electric heat tracing control and monitoring

    Page(s): 516 - 520
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    Addressable power line carrier (ADPLC) is the latest technology for electric heat-tracing systems. ADPLC systems are unique in that dedicated instrument wiring is not required for centralized temperature control and monitoring. The applications and value of ADPLC systems are examined View full abstract»

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  • Optical dust deposition meter

    Page(s): 508 - 513
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    Coal dust is produced in coal mines during normal mining operations and by the movement of men and machines. The operation of a prototype optical dust deposition meter used to measure the mass-loading density of stratified coal and rock dust layers to assess the flat coal dust hazard is described. The meter determines the surface-loading density of a dust layer by measuring its optical reflectivity. The theory of the prototype unit's operation is developed and compared with experiment. The studies showed that the prototype unit is capable of measuring coal dust and rock dust surface-loading densities of up to 7 mg/cm2 for coal and 10 mg/cm2 for rock dust. This is well within the hazard range with an accuracy of about ±5%. Results of the laboratory and experimental mine testing of a second portable meter are reported View full abstract»

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  • Energy comparisons between electric melting and gas firing for the production of rolled glass

    Page(s): 503 - 507
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    The production of glass by electric melting and gas firing is compared on a direct basis. The product and processes are compared from a quality, operational, energy, construction, and economic viewpoint. It is argued that electric melting is much more BTU-efficient but, depending on the cost of local energy, not always cost-efficient 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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