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Telecommunications Energy Conference, 1984. INTELEC '84. International

Date 4-7 Nov. 1984

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Displaying Results 1 - 25 of 105
  • International Telecommunications Energy Conference

    Page(s): i
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    Freely Available from IEEE
  • Copyright page

    Page(s): ii
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  • Greetings

    Page(s): iii
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  • 1984 Intelec Management Committee

    Page(s): iv
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  • Intelec Advisory Committee

    Page(s): v
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  • Conference Executive Committee

    Page(s): v
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  • Technical Program Committee

    Page(s): vi
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  • [Acknowledgements]

    Page(s): vi
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  • Table of contents

    Page(s): vii - xi
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  • The Increasing Significance of Electricity: Strategic Implications for Energy Planning

    Page(s): 1 - 7
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    This paper examines the fundamental changes that have taken place in the U.S. energy-economic relationships over the past decade. Special attention is focused on one particular form of energy, namely electricity. It is argued that the generally accepted prognosis for sluggish primary energy growth over the next two decades does not necessarily apply to electricity. The factors behind this dichotomy are examined and their implications discussed. View full abstract»

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  • The Convergence of Central Office and Customer Located Power Equipment

    Page(s): 13 - 17
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    This paper reviews the power system used in British Telecom (BT) Telephone Exchanges (Central Offices) and the growing customer located power equipment demands. The increasing switching density of modern telecommunications equipment and the changes in power density of converters and batteries are the major factors in the revolution in power supply systems. The adoption by BT of high frequency converters and sealed batteries as the recommended provision for new power plant is a major step forward and leads to the possibility of standard power modules suitable for both Central Office and customer located systems. With the expansion of telecommunication systems and facilities, flexibility of power supply is a major factor and the advantages of standard power units in modular form, which can be built into a variety of systems meeting the reliability requirements, virtually off the shelf, are discussed. The present power rack system using relatively small rectifiers increases the overall reliability. The next step and the limit of convergence are considered. View full abstract»

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  • Semiconductor Component Technologies and Packaging Structures in Future Switching Systems - Their Impact on Power Systems

    Page(s): 23 - 26
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    For fifteen years the evolution of the telecommunication exchanges has been determined by the development of the semiconductor technology. This paper deals with the use of LSI, VLSI, Gate Arrays, Cell Library and Full Custom Circuits in telecommunication equipment. The use of these circuits will affect packaging structures and the power systems in the future. Network architecture will also be affected by the use of these circuits, but this is mentioned only briefly. View full abstract»

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  • New Power Feed Techniques for Telephone Subscribers

    Page(s): 27 - 33
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    This paper describes power feed techniques for telephone subscribers in a metallic two-wire digital subscriber loop system and optical fiber subscriber loop systems. In a metallic two-wire digital subscriber loop system, Digital Service Unit (DSU) and Digital Telephone (DTEL) are installed on the subscriber premises. Since the equipment has additional new service functions compared with the conventional analog telephone, the power consumption of the equipment is increased. Therefore, it is difficult to feed the equipment sufficiently using a conventional 48V constant-voltage power supply. A constant current supply method from the central office is suitable because constant power can be supplied with little energy loss, even if subscriber's line distance varies. It is also possible to simplify the DC-DC converter circuit in DSU. A high conversion frequency (150kHz) multi-output constant current converter has been developed for power feeding in NTT. The converter can feed eight subscribers and has good constant current output characteristics. In optical fiber subscriber loop systems, it is difficult to feed the customer's equipment with power from the central office. Therefore, an uninterruptible DC power supply, which includes batteries, has to be installed on the subscriber's premises. The power supply is composed of sealed lead-acid batteries and a multi-input converter which has rectifier and DC-DC converter functions. This low-cost converter is very small compared with the conventional rectifier and DC-DC converter. Sealed lead-acid batteries are used in the power supply due to low cost and easy maintenance. View full abstract»

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  • Batteries in Power Supplies for the New Telecommunication Services

    Page(s): 34 - 40
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    A General survey on battery power supply today and tomorrow within the telecommunication services of the F.R. of Germany. The growing number of new services and modern equipment will be supplied with energy using the existing AC and DC power distribution systems. The principle of permanent power supply demands stored energy either in the fuel tanks of IC (Internal Combustion) Generator sets or in batteries. The network will be extended by optical fibre cables not capable of transporting energy. Computorized equipment requires increasingly continous power supply for memory back up. The three main categories which need stored energy in batteries are: - the central services (as exchanges. repeator stations, a.s.o.) - the subscriber premises (e.g. with optical fibre cables) - the memory backup (in various equipment) For the first category the station battery - central or decentral - will be the solution also in the future. For the decentral power equipment medium and small sizes of rechargeble batteries in maintenance free desing are preferred. Only smaller sizes of rechargeble batteries in maintenancefree design are prefered for the second category. For the third category: energy supply of memory back up's, the design alternative is between primary cells (Lithium) and secondary cells (NiCd button cells). For all types of batteries there is a high demand on reliability during service life and on maintenancefree operation. This requires changes in design of the existing battery types and or newly developed batteries. View full abstract»

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  • The Comparison of Flooded, Gelled and Immobilized Lead-Acid Batteries

    Page(s): 41 - 44
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    The maintenance free battery has received wide acceptance in a number of applications in recent years. Very recently, large power, maintenance-free batteries have been developed which can be employed in telecommunications applications. Maintenance-free batteries offer advantages in reduction of maintenance and venting requirements and avoid spillage during transit with minimal loss in electric performance. Life performance data on the large power batteries is not yet available although this product has been designed with the same lead components used in 20-year flooded batteries. View full abstract»

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  • Maintenance-Free Sealed Lead Batteries with Immobilized Electrolyte - Construction with different Grid Type Plates and/or Tubular Positive Plates - Applications in Industry and in Civil and Military Communication Systems

    Page(s): 45 - 52
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    This battery system is presently being manufactured with a capacity of 1 Ah to 110 Ah in grid type plate construction between 12,5 Ah and 200 Ah in Block design and with a capacity of 70 Ah to 1,350 Ah with tubular plates and has proved its efficiency in all kinds of battery-supported appliances, from the small portable equipment battery in cyclic operation to the big spare power supply installations in industrial standby/parallel/float operation. After having proved reliable for nearly 25 years in any kind of telecommunication equipment, from radiophone and burglar and fire alarm systems to uninterrupted power supply of most modern computers, this battery system, in special construction laid out for extremely long life, is presently being applied for glass fibre cable of the BIGFON pilot project (Wideband integrated glass fibre local communication network) carried out by the Deutsche Bundespost. Introduced in 1958, it was the first realy maintenance-free lead battery system in grid type plate construction on the market and was supplemented by a tubular positive plate construction in 1975, a development which took place by order of the German Ministry of Research and Technology and the Ministry of Defence. In Germany, it has been made a DIN standard, a military standard, and the draft of an international TEC standard has been presented. View full abstract»

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  • A Long Life Totally Maintenance Free Modular Battery for Telecommunications Standby Power

    Page(s): 53 - 57
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    Lead-acid storage batteries are used extensively in the Telecommunications industry as a source of standby power in the event that utility supplied electrical power, is for whatever reason, interrupted. Lead-acid batteries offer many advantages over alternative power sources, the most important one being low cost, reliable power. However, despite all of their inherent advantages, they do possess several unpleasant shortcomings, especially from the user's point of view. During charging, water contained in the electrolyte of lead acid batteries is electro-chemically broken down into hydrogen and oxygen gas which escapes into the atmosphere. This characteristic creates the need to periodically replace lost water, and to provide adequate means to remove the dangerous gasses that are released. Furthermore, as the gasses are emitted from the cells, acidic mist is carried with them, which causes corrosion of battery hardware, racks and any equipment which is located nearby to the battery. These idiosyncrasies have lead users of lead acid batteries to contain them in isolated rooms, separate from the telecommunications equipment which they support. Finally, conventional lead acid cells are installed on steel racks to make up a battery, which is a costly, labor intensive process. Also, the steel rack packaging concept requires a large amount of floor space leading to increased battery room sizes. A new lead acid battery, utilizing the principal of oxygen recombination, has been developed which solves all of the problems previously associated with conventional batteries, as listed above. View full abstract»

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  • Low Maintenance Batteries in Combination with Battery Supervision System

    Page(s): 58 - 62
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    Lead-acid batteries in modern design and with correct choice of alloy have a topping up interval of several years. However, this does not mean that the battery can be left without service during the corresponding time. The battery needs supervision of cell voltages, densities, levels and temperatures much more often than water filling, which means that the long topping up intervals of modern batteries cannot be fully utilized. By combination of a low maintenance battery and a battery supervision system for cell voltages, current, battery temperature and electrolyte level, a minimum of maintenance and a maximum of availability is obtainable. Furthermore a more optimized service life of the battery will be possible by use of the battery supervision system. In this paper a more detailed description of such a combined system of battery and supervision will be outlined. View full abstract»

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  • A New Concept: Intermittent Charging of Lead Acid Batteries in Telecommunication Systems

    Page(s): 67 - 71
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    Present communication systems operate their batteries in a full float mode. This mode provides a constant charge voltage which is sufficient to maintain the batteries in the fully charged state. However, this charge voltage causes an increased rate of positive grid corrosion - the accepted life-limiting failure mode of lead acid batteries. The new concept reduces the time the batteries are on float and, as a result, extends the life of the battery. This is accomplished by maintaining the batteries at their open circuit potential for most of the time and then periodically recharging them. This paper also describes a system that has been developed to provide for intermittent charging and to test each battery string, on a monthly basis, to assure proper battery availability. View full abstract»

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  • 100 Amp Switched Mode Charging Rectifier for Three-Phase Mains

    Page(s): 72 - 78
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    Uninterruptible power supply increases the availability of telecommunication systems decisively. Consisting of a large battery plant for 48 V or 60 V dc with a suitable charging rectifier, this fundamental power source maintains the secure operation of central offices or PBXes, independent of mains supply fluctuations. Considerable volume and cost are the well known disadvantages of such power systems. While the battery producers have been developing the new generation of sealed cells, designers of rectifiers have been investing remarkable efforts in reducing the size of large current range units. It is only the success on both fields that enables a reasonable integration of complete uninterruptible power supply within the communication system. The best way of avoiding the very large magnetic components used in SCR of ferro resonant controlled rectifiers, is to apply the switched mode technology. This paper is to present our latest achievements on the field of SM charging rectifiers for three-phase off-line operations. Power range up to over 8 kW and high efficiency of about 95 % will be discussed as the main features of the new power conversion system. View full abstract»

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  • AC/DC Power Supply Module

    Page(s): 79 - 82
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    First Page of the Article
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  • High Power, High Frequency, Switch Mode Rectifier

    Page(s): 83 - 87
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    There are many types of inverter circuits for switching power supply. A full bridge inverter consisting of four transistors is suitable for high power, but magnetic asymmetrical phenomena of transformer easily occurs, especially at high frequency. Storage time is also a problem in bipolar transistors. The authors analyzed the asymmetrical phenomena of transformer in a bridge inverter, and found a method which can be used to decide: which circuit elements are appropriate, how to control the driving signals, and how to drive the transistor. We made a small size, high power, high frequency, switch mode rectifier using a high power bipolar transistor at 20 kHz conversion frequency. View full abstract»

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