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Industry Applications Magazine, IEEE

Issue 6 • Date Nov/Dec 1995

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Displaying Results 1 - 5 of 5
  • Computer-aided selection and verification of circuit breakers

    Page(s): 26 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    Procedures governing medium- and high-voltage breaker application, although conceptually tractable, tend to be repetitive for large systems. Hand calculations can become quite laborious when assessing safety margins of installed switchgear on systems that have experienced sudden growth. This article describes how a computer can be used as an efficient tool to address these concerns. The discussion focuses on how the computer can be used to interface the short circuit study results to the breaker modules, on how breaker adequacy evaluation can be computerized, and finally how these calculations can be extended to yield automated breaker selection according to user-defined criteria and breaker rating structures. The discussion is confined to the North American breaker application procedures and rating structures as tabulated in the ANSI Standards, and addresses only short circuit current interrupting requirements View full abstract»

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  • Modeling of electrostatic-based pesticide spray systems

    Page(s): 33 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    A microscopic model for the electrostatic spraying system is presented to investigate the effect of the voltage applied to the induction nozzle on the droplet's charge, mobility, and charge-to-mass ratio. The variation of these parameters along the jet was also included. The model also lays particular emphasis on the effect of the applied voltage on the spray current and the charge density at the nozzle. A macroscopic model for the electrostatic spraying system is also presented. The objective of the model was to study the spatial distribution of the droplet charge density, transit time, and trajectory in the region between the nozzle and the target in terms of the flow velocity of the spray and the space-charge-produced electric field. On the macroscopic scale, both the droplet charge density and the spray current increase with the voltage applied to the charging electrode. With the decrease of the spray flow velocity, the space-charge-produced electric field becomes dominant and tends to: contract the droplet trajectories toward the axis of the spray system, and hence enhance the droplet deposition efficiency; and decrease the charge density at the target with the possibility of minimizing back-ionization. On the microscopic scale, induction charging eliminates the ion current from the current to the target and the associated back-ionization. The calculated droplet charge and charge-to-mass ratio which increase with the voltage applied to the charging electrode, agreed with the values reported previously View full abstract»

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  • Contactless charging and communication for electric vehicles

    Page(s): 4 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    Charging batteries in electric vehicles needs to cover several aspects including electrical safety, the weight of an onboard charger, different types of chargers needed by different types of batteries, low line disturbance with high efficiency, and the influence of the charging process on the lifetime of the battery. Another important problem is the communication between the vehicle and the outside world during the charging process. This article describes a system combining energy transfer and signal transmission in one unit, which is able to solve all of the above-mentioned problems. Minimal power electronic components are installed in the vehicle. The system uses contactless energy transmission employing an inductive high-frequency coupler. The charging process is monitored and controlled by an onboard charge meter, which can communicate with the converter outside the vehicle via the signal transmission included in the inductive coupler. A laboratory setup able to transfer up to 5 kW was built to demonstrate the performance of the system. The efficiency of the overall system, including all filters, converters, and rectifiers, is at a power level of 5 kW better than 92%. The used gelled lead acid battery, 35 Ah and 288 V, was made from 24 battery modules View full abstract»

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  • Control batteries: power system life savers

    Page(s): 18 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    If protective devices and relays represent the ≫OPEN "nerves” of a medium- or high-voltage electric power system, the DC control battery distribution system represents the system's “bloodstream.” The battery distribution system delivers energy the battery provides to the control circuits of AC circuit breakers and other electrically operated interrupting equipment (the “muscle” of the electric power system), allowing operation. The battery is the DC power distribution system's “heart.” Reliable control battery systems assure proper functioning of well designed, installed, and maintained power systems. Battery system failure jeopardizes a power system by eliminating the DC control power source for AC system circuit breakers and protective devices. Failure to protect DC system components also could result in disastrous consequences for the battery system itself. The author discusses battery faults, battery protection, and battery maintenance. Battery charger faults and protection are also briefly mentioned, as are load protection, and DC system protection View full abstract»

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  • UPS applications: a mill perspective

    Page(s): 12 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    This article results from the experience of installing a number of uninterruptible power supply (UPS) systems for various projects. It attempts to describe typical applications in a pulp and paper mill, determines how to evaluate whether a UPS system should be used, and suggests some alternative approaches to the problem. There are several types of UPS configurations available. Although rotating types are extensively used, the static type is more prevalent and is the basis for most of the discussion. Many applications have potential problems with power quality and availability. Factors are listed that will help determine whether a UPS system should be installed. Typical applications in pulp and paper mills are listed and discussed. Problems from some actual installations are described and alternative approaches are examined. Power quality and availability is a design consideration that requires careful attention to achieve the desired result. It will be more important in the future as utility power systems become less reliable View full abstract»

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Aims & Scope

IEEE Industry Applications Magazine reports on the development 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; the encouragement of energy conservation; and the creation of voluntary engineering standards and recommended practices.

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Meet Our Editors

Editor-in-Chief
H. Landis "Lanny" Floyd