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Oct. 30 1994-Nov. 3 1994

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Displaying Results 1 - 25 of 104
  • Proceedings of Intelec 94

    Publication Year: 1994
    Request permission for commercial reuse | PDF file iconPDF (18 KB)
    Freely Available from IEEE
  • High power factor operation of discontinuous current mode series-parallel resonant converter

    Publication Year: 1994, Page(s):359 - 366
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (568 KB)

    This paper presents the operating principle, analysis, design, simulation and experimental results for a high frequency (HF) transformer isolated AC-to-DC series-parallel resonant converter (SPRC) operating on the utility line, in discontinuous current mode (DCM). The equivalent models, the state space analysis of the SPRC in DCM are presented. PROMATLAB software is used to solve the equations and... View full abstract»

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  • A novel three-phase utility interface minimizing line current harmonics of high-power telecommunications rectifier modules

    Publication Year: 1994, Page(s):367 - 374
    Cited by:  Papers (79)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (656 KB)

    Based on the combination of a three-phase diode bridge and DC/DC boost converter a new three-phase three-switch three-level PWM rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage and low blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power supply... View full abstract»

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  • Input current controlled DC interconnection converter for fuel cell systems

    Publication Year: 1994, Page(s):375 - 380
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    Fuel cells are a remarkably efficient energy generator that also protect the global environment. NTT is developing a fuel cell energy system that supplies generated electrical energy to telecommunications equipment. It is a cogeneration system; the heat energy recovered is used to cool the telecommunications equipment. In a DC interconnection system, along with the commercial AC power, the fuel ce... View full abstract»

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  • New method for measuring the electrical resistivity of a thin layer of earth

    Publication Year: 1994, Page(s):381 - 384
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    In order to maintain an adequate safety level in a substation, resistivity of the surface layer must be estimated in situ and during a sufficiently long period of time to take into account the various effects of the climatic conditions. The purpose of the surface layer is to keep the exposure to touch and step voltages to a safe value for a person standing inside or near a substation yard. Convent... View full abstract»

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  • The use of ratiometric measurements to determine battery status

    Publication Year: 1994, Page(s):491 - 496
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    Until the introduction of the valve-regulated Pb-acid (VRLA) cell the typical telecommunication battery system used flooded Pb-acid cells. These required continual monitoring to ensure that the electrolyte levels were maintained and that the specific gravity was within certain limits. When properly maintained, these battery systems were extremely reliable and had an operational life often in exces... View full abstract»

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  • Quality assurance in telecommunications energy and grounding system connections

    Publication Year: 1994, Page(s):385 - 391
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (596 KB)

    The development of a connection system to meet the rigorous demands of any telecommunications power and grounding circuit offers a most challenging task. Each component must be designed to provide the highest degree of quality and reliability. One of the most important components in this system is the connector. There have been substantial advances in the development of many new types and styles o... View full abstract»

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  • An expert management system for VRLA batteries in remote telecommunications centers

    Publication Year: 1994, Page(s):497 - 504
    Cited by:  Papers (5)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    Reliability and longevity of “valve-regulated Pb-acid” (VRLA) batteries in noncontrolled environments is one of the foremost problems in telecommunications today. With the increasing trend for network decentralization and deployment of electronics outside and with the thrust to reduce maintenance and support staff, the need to prolong life and increase reliability of VRLA batteries whi... View full abstract»

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  • Computer simulation and verification of DC power plants for seismic qualification

    Publication Year: 1994, Page(s):229 - 237
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    Power plant integrity and resistance to earthquakes are of special interest to those living in areas of high seismic risk. Power products must be designed and tested to ensure survivability. A cost effective analytical approach using PC based software is described and verified. Medium sized power plants are selected for structural examination. They are -48 VDC plants with maximum current capacity ... View full abstract»

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  • Grounding and ground fault protection considerations specific to emergency/standby generator sets

    Publication Year: 1994, Page(s):392 - 399
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    Careful consideration of the grounding arrangements of AC generators used in emergency and standby power systems is essential for optimum continuity of power for critical loads and for the safety of personnel. There are grounding and ground fault protection considerations that are specific to emergency/standby generators when interconnected to a commercial AC power source through transfer switch e... View full abstract»

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  • Analysis and interpretation of conductance measurements used to assess the state-of-health of valve regulated lead acid batteries

    Publication Year: 1994, Page(s):282 - 291
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB)

    This paper presents data showing conductance aging of new valve-regulated Pb-acid (VRLA) secondary cells and capacity/conductance aging of older cells. It presents data showing the comparative accuracy of several techniques for selection of a cell conductance value suitable for use in field determination of cell pass/fail conditions based on either capacity failures below 80% or below 50% of rated... View full abstract»

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  • Electrical protection for multimedia workstations

    Publication Year: 1994, Page(s):238 - 244
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    Electrical protection for multimedia workstations is essentially dependent upon the product safety listing process. In other words, workstation assemblies and peripherals utilize power, grounding and protection schema that are necessary to obtain the listing mark (such as UL or CSA) for certified product safety. At the time of writing, there is no standard that specifically addresses workstations.... View full abstract»

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  • Intelligent power plant configurations

    Publication Year: 1994, Page(s):512 - 516
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    As US WEST developed the new Service Assurance (SA) Center concept, for centralized alarm monitoring, network administration, engineering, and control of all Telecommunications Network Elements (TNE) it became apparent that the personnel developing maintenance databases for monitoring the power alarms had absolutely no idea of the physical or functional characteristics of the hardware required to ... View full abstract»

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  • Interface specifications for a global grounding topology

    Publication Year: 1994, Page(s):400 - 406
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (456 KB)

    After briefly reviewing the global bonding and grounding environment in general terms, specific interface requirements of telecommunication equipment which are needed to ensure robustness and reliability in the global environment, are discussed in detail. Areas covered in the discussion include communication links (both AC and DC coupled types), DC and AC power source referencing, safety requireme... View full abstract»

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  • A recommendation for centralized powering of local network elements

    Publication Year: 1994, Page(s):108 - 114
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (560 KB)

    The challenge for the telecommunications power engineer is to devise a cost-effective and reliable means of providing power for telephone sets (POTS) over an evolving local network in a manner that allows a smooth transition to the network envisioned. This paper discusses the networks, reviews proposed powering arrangements, and recommends that centralized powering of network elements, with hybrid... View full abstract»

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  • High frequency alternating current power distribution

    Publication Year: 1994, Page(s):292 - 296
    Cited by:  Papers (24)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    The paper introduces high frequency alternating current (HFAC) power distribution as a new option in powering the equipment in telecommunications applications. A detailed comparison with powering schemes presently used in the telecommunication industry is part of the paper. The comparison is oriented towards the parameters of regulation, efficiency, input voltage range, output/input ripple, power ... View full abstract»

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  • Impedance testing-is it a substitute for capacity tests?

    Publication Year: 1994, Page(s):245 - 249
    Cited by:  Papers (15)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    Capacity tests are used to reliably determine lead acid battery capacity. The results of the capacity tests are then used to evaluate whether the battery can continue in service or needs to be replaced. Unfortunately, many batteries do not receive regular capacity tests. This occurs because of perceptions that: the test is difficult to perform; takes too much time; the battery is too important to ... View full abstract»

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  • The central office power plant of the future

    Publication Year: 1994, Page(s):517 - 522
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    The author describes an integrated system approach which would create a comprehensive power system that would have the flexibility to serve the power needs of the future central office, with systems to support multimedia and various operational support systems. All requirements for surge immunity, even higher than normal, could be met in a manner where a complete pre-engineered, pre-packaged, pre-... View full abstract»

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  • Rectifier input current distortion-how much can be permitted? Implications of existing standards and other considerations

    Publication Year: 1994, Page(s):407 - 412
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Harmonic pollution of electrical power systems is a subject of increasing importance. Power converters are a type of load that generates current harmonics, and the designers of converter equipment are highly concerned with this problem. Two existing standards, the European EN 60 555-2 and the American IEEE Std 519 formulate the requirements on harmonic contents. This paper analyses these standards... View full abstract»

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  • A novel ZVS multi-resonant converter with rectifiers' deadtime control operated in 20 MHz range

    Publication Year: 1994, Page(s):115 - 122
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (508 KB)

    A novel zero-voltage-switched multi-resonant power converter is presented. The rectifier deadtime control proposed in this paper enables this power converter to achieve zero-voltage-switching in any load range and to operate from full load to no load within a high and narrow frequency range. Experimental results of two power converters designed for 2 MHz and 20 MHz operation and analysis are prese... View full abstract»

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  • Three-wire DC distribution to telecommunication equipment

    Publication Year: 1994, Page(s):297 - 300
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    This paper takes a new look at the -48 V power distribution widely used for providing power to telecommunication equipment, and at the methodology used for grounding and bonding of both the power system and the powered telecommunication system. In contrast to AC distribution, the DC distribution used in telecommunications and its associated grounding are not extensively covered in electrical codes... View full abstract»

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  • Maintenance and reliability of standby battery systems: flooded vs. valve regulated lead acid battery

    Publication Year: 1994, Page(s):250 - 255
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    Flooded and VRLA cells should be considered as battery types which complement each other. VRLA cells are here to stay because of their gas-free nature, low maintenance, and high energy density. They should not be considered indiscriminately as substitutes for flooded cells. The special sensitivities of VRLA should be taken care of in a system approach. In particular the system float voltage should... View full abstract»

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  • Alternatives for powering the hybrid fiber/coax networks

    Publication Year: 1994, Page(s):83 - 89
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (428 KB)

    The characteristics of three types of power distribution systems for a drop segment of a hybrid optical fiber/coaxial cable telecommunication architecture are compared: DC; low frequency AC; and high frequency AC. It is shown in the paper that the high frequency distribution system has potential advantages in terms of high efficiency, small size of power converters, and low cost of powering. A pro... View full abstract»

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  • On the low-frequency noise of DC-to-DC converters with random-switching control

    Publication Year: 1994, Page(s):451 - 456
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    The low-frequency output noise that is caused by introducing random-switching control into the DC-to-DC power converter is discussed quantitatively. A modified power converter model involving the unintended effect of random switching is derived from the consideration of noise-generation mechanisms. After a theoretical analysis based on the model, it is clarified that the magnitude of output noise ... View full abstract»

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  • Communication link between power converters and computer systems for system and alarm management

    Publication Year: 1994, Page(s):22 - 29
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    Communication between computers and power converters has become more and more important. Communication between power converters and central processing equipment totally changes the traditional routine of maintenance and service departments. Introducing a communication link is a very effective way of controlling the performance of a power converter. However, the way of communication must be careful... View full abstract»

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