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Telecommunications Energy Conference, 2004. INTELEC 2004. 26th Annual International

Date 19-23 Sept. 2004

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Displaying Results 1 - 25 of 129
  • Safety performance for phosphate based large format lithium-ion battery

    Page(s): 146 - 148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB) |  | HTML iconHTML  

    The use of lithium-ion batteries in many of today's electronic consumer products has increased significantly due to the advantages of high energy density, high cell voltage, and longer shelf life over that of comparable battery chemistries. The cell chemistry of conventional lithium-ion batteries has been limited by the choice of suitable lithium liberating cathode materials i.e. the three oxide electro active materials: LiMn2O4, LiCoO2 and LiNiO2 (lithium-manganese, lithium-cobalt, and lithium-nickel respectively). These materials are generally found to offer high electrochemical performance at the expense of poor thermal stability. The three lithium oxide's thermal instability when over-charged has limited the application of these materials to small and relatively low capacity lithium-ion batteries. The novel use of a phosphate-based material in the cathode has been found to offer many of the advantages of traditional lithium-ion chemistries without sacrificing the safety necessary in a large format application. In this paper, the results of safety testing comparing phosphate-based cells and the most popular of the three lithium oxide materials (lithium-cobalt), is presented. Test data will show that the safety circuitry used in popular lithium-cobalt 18650 cylindrical cells will not prevent an event or propagation of an event if thermal runaway occurs within one cell in a battery pack. In contrast, abuse testing of phosphates based cells shows no thermal events under identical conditions. View full abstract»

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  • A new stand-alone hybrid power system with wind generator and photovoltaic modules for a radio base station

    Page(s): 254 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB) |  | HTML iconHTML  

    This work proposes a new stand-alone hybrid power system with a wind turbine generator and photovoltaic modules for a radio base station. We studied the system characteristics by simulation on Yonaguni Island, where the wind speed is over 4.0 m/s throughout the year, and the average annual wind speed is about 7.0 m/s. It was found that the base station equipment needs a wind generator output power of 8 kW, a photovoltaic output power of 7.4 kW and 177 kWh storage batteries for a system operation rate of 100%. View full abstract»

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  • Innovation in switch buildings

    Page(s): 270 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    This paper outlines the environment and logistical problems that are common to developing countries roll-outs and the solution to switch buildings that was developed to overcome these problems. Emphasis is placed on the financial and market share advantages of a fast roll-out. MTN Nigeria faced all these challenges in a race to roll-out in a market that was and still is hungry for an efficient communication system and the challenge is to roll-out quickly, professionally, cost effectively and with a product that would withstand the Nigerian environment. View full abstract»

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  • Cost/benefit analyses of a new battery pack management technique for telecommunication applications: future directions with fuel cell/battery systems

    Page(s): 73 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (972 KB) |  | HTML iconHTML  

    A new approach to battery pack and fuel cell management, the battery health manager-BHM™ and the fuel cell health manager-FCHM™, both cell-based techniques that manage power supplies without disrupting operations, was described at INTELEC 2002. Using the BHM, each cell (or module) in a battery pack can be cycled to up to a full-load discharge, and then smart charged, in a regenerative cycling process, to optimize cell capacity and life, without removing the cells from the battery string or compromising inter-cell connections. A historical database providing full state-of-health (SOH) information for backup battery packs is now available based on BHM™ technology. In addition to conventional information such as float voltage and current, temperature and internal resistance, the database created by BHM™ technologies is able to provide critical SOH information including voltage, current, and temperature for up to full discharge cycles on all the individual cells of the backup battery pack. A cost/benefit analysis of this powerful cell based technique for telecommunication applications is shown using this database as well as previously published data. A new concept, the fuel cell health management (FCHM™) technique, is applicable to fuel cell stack management. Fuel cells and fuel cell battery/hybrid systems are being considered for telecommunication applications. Because of the difficulty in storing hydrogen, in many fuel cell applications the hydrogen is produced chemically from fuel such as methanol or natural gas using a fuel reformer to strip out the hydrogen. In addition to hydrogen and carbon dioxide, reformates contain significant concentrations of carbon monoxide (CO) and H2S, catalyst poisons which degrade the fuel cell electrical output. Recent results for a PEM fuel cell operating on 100 ppm CO show however that there is a significant loss of overall efficiency when compared with results for pure hydrogen. As an alternative cheaper approach than current practices to dealing with hydrogen contaminants, we have applied pulsed oxidation for the removal of CO and regeneration of CO poisoned cells using a microprocessor-based fuel cell health manager. We will present results for the regeneration of Pt a- nd Pt-Ru anodes in a PEM fuel cell fed with CO concentrations as high as 10,000 ppm (1% CO). The results of a cost/benefit analysis for the use of a FCHM™ on a 4 kW fuel cell system are also presented. View full abstract»

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  • DC-DC converter controlling input supply voltage of five-level inverter

    Page(s): 289 - 295
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (627 KB) |  | HTML iconHTML  

    For various electronic equipments including both analog and digital circuits, sometimes requires power supplies with different supply voltages. We propose a novel chopper, with simple circuit configuration, which can supply to two or more different output loads. This converter provides wide control output voltages by varying duty ratio using switching devices. View full abstract»

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  • Improving the efficiency of cooling systems in data centers considering equipment characteristics

    Page(s): 32 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (686 KB) |  | HTML iconHTML  

    Internet data centers are helping to expand the network society throughout the world. These data centers require air conditioning to operate, and raising the efficiency of their cooling systems can have significant benefits such as the prevention of equipment failure and the saving of energy as well as improved cost performance. A data center in which much heat-generating equipment has been installed produces a large amount of heat, and achieving a balance between cooling power and fan driving power holds the key to greater efficiency. This study consisted of: 1) full-scale mockup experiments that consider the ventilation of even heat-generating equipment installed in racks; and 2) efficiency evaluation and intake-temperature evaluation based on measurement results for fixed heat-generating equipment using ventilation volume and interequipment gap area as parameters. The results of these evaluations revealed that intake temperature could be predicted when varying these two parameters. View full abstract»

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  • Small-signal averaged model and simple control of a high-power-factor three-phase/switch/level fixed-frequency PWM rectifier for high-power telecommunications

    Page(s): 449 - 456
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (690 KB) |  | HTML iconHTML  

    This work presents a new small-signal model of a three-phase three-switch three-level boost-type rectifier operating with a fixed switching frequency. The proposed model is obtained by linearizing the (d,q)-averaged representation of the converter in the neighborhood of a desired unity-power-factor operating point. The linearized model is expressed both in the time domain, using the state representation, and the frequency domain by computing the corresponding transfer functions. These latter are then used into the design of linear-control-based regulators in order to ensure the convergence and stability of the system around the desired set point. The control system is implemented numerically using Matlab/Simulink, and simulation experiments are carried out in order to test and verify its tracking and regulation performance, as well as its robustness towards load or mains source disturbance. View full abstract»

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  • Analytical estimation of common mode conducted EMI in PWM inverter

    Page(s): 569 - 574
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (637 KB) |  | HTML iconHTML  

    In PWM inverter system, the high dv/dt and di/dt due to the fast switching of IGBT could bring serious EMI issues. How conducted emission measurement should be made are specified. Based on the study of mechanisms on common mode conducted electromagnetic interference (CM EMI) associated with a single phase PWM inverter, the origin and propagation path of CM EMI noise are highlighted. Compared with buck converter, a simple equivalent circuit is proposed to study the CM EMI. Time and frequency domain analysis is conducted to obtain CM current waveforms and noise spectra in 10 kHz-30 MHz frequencies. The simulated CM EMI waveforms are compared with the actual experiments to verify the validity of the proposed model. The modeling method described can be readily extended to a three-phase PWM inverter. View full abstract»

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  • Modeling and performance studies of a fuel-cell powered boost converter

    Page(s): 713 - 717
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (617 KB) |  | HTML iconHTML  

    The proton exchange membrane (PEM) fuel cell is becoming popular as an alternate power source for various applications. The paper presents a novel circuit model for a PEM fuel cell that can be used to design and analyze fuel-cell power system. The PSPICE-based model uses BJTs and LC elements available in the PSPICE library with some modification. The static and dynamic characteristics obtained through simulation are compared with experimental results obtained on a commercial fuel-cell module. The possibility of operating the fuel cell at its maximum power point is investigated. The performance of the fuel cell module when feeding a boost converter is studied through simulation and experiment and the waveforms are presented. The need for a buffer capacitor to make up for the voltage drop under transient switching operation is established. View full abstract»

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  • A low-cost fuel-cell (FC) power electronic system (PES) for residential loads

    Page(s): 468 - 473
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (627 KB) |  | HTML iconHTML  

    We describe a low-cost power-electronics system (PES) for a solid-oxide fuel cell (SOFC) power system. The PES consists of a (DC/DC) zero-ripple boost converter (ZRBC) followed by a soft-switched multilevel high-frequency (HF) inverter and a single-phase cycloconverter. The zero input ripple-current feature of the boost converter improves the durability of the SOFC, while reducing the size and cost of the inductor. The multilevel arrangement of inverter switches reduces the voltage stress on the switches is sine-wave pulse-width modulated SPWM and has phase-shifted ZVS turn-on. The cycloconverter, switches at line frequency when the power transfer is active; otherwise, it switches at the switching frequency (20 kHz). A 1 kW prototype of the proposed PES achieved an overall efficiency of 91%. We present a detailed description of the operation of the PES and its key features and advantages. Finally, experimental results showing the performance and operation of the PES are demonstrated. View full abstract»

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  • A monitoring system implementation in China

    Page(s): 489 - 494
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB) |  | HTML iconHTML  

    Today's network structures within datacom and telecom networks with a large number of sites, high requirements of availability, reliability and profitability puts high demands on the operation and maintenance organization to handle the mission critical systems including DC power, AC power, climate and battery systems in an efficient way. This paper will describe a monitoring system used for the mission critical systems within telecom and datacom networks. More than 50,000 sites all over China have the monitoring system installed. The paper will present the design and architecture of the present monitoring system. An enhanced site solution, which is based on the existing site solution, will also be presented. View full abstract»

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  • Energy management & limiting CO2 emissions in the telecommunications powering environment

    Page(s): 615 - 622
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (819 KB) |  | HTML iconHTML  

    The minimisation of energy costs for telecommunications companies is essential for their business, as it has a direct affect on their overall profit and hence shareholder dividend. An emerging concern on a global and regional scale is the emission of "greenhouse" gases, CO2 in particular. Developed nations and major companies are seeking means by which greenhouse gas emissions may be reduced, thereby meeting their actual or perceived global obligations as good "corporate citizens". In the field of telecommunications, both these goals have to be achieved whilst maintaining very high levels of network integrity. This presents a series of challenges to the operators and designers of telecommunications powering systems. The aim of this paper is to present the holistic approach that Silcar, the operator, designer, constructor and provider of Telstra Corporation Limited's (Australia's national carrier) power equipment, proposes to take in order to progress these goals. Silcar has developed strategies and proposed policies for energy management and greenhouse gas emission reduction via the following actions: reduction in the requirement for excess rectifier capacity to meet battery recharge requirements; isolation of excess rectifier capacity to improve operating efficiency of remaining "on line" rectifiers; development of solar powered solutions for thermal management of remote equipment enclosures; cost-benefit analysis of replacement of inefficient legacy rectifiers with high efficiency rectifiers; reduction of heat dissipation of power equipment to air-conditioned telecommunications equipment environments; modification of battery maintenance practices and equipment commissioning practices to limit maximum demand; re-appraisal of need for coolant heating systems on diesel generators; evaluation of quantitative negative impact of supply authority AC power failures on energy cost, with a view to obtaining discounts. All process changes will be risk assessed, and all benefits quantified in regard to cost savings and greenhouse gas emission reduction. View full abstract»

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  • Real time VRLA life test or how a small difference can have big effects

    Page(s): 314 - 320
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1008 KB) |  | HTML iconHTML  

    Stationary lead acid batteries can experience temperature differences within a string especially when operated as 110 V or 480 V back-up batteries. In the present study the influence of a ∼3°C temperature difference on the corrosion induced capacity loss of VRLA monoblocs during 7 and 9 years of float operation in a 5 tier rack installation is reported. Corrosion sensitive VRLA monoblocs can have residual capacity values ranging all the way from 3% to 110% in the same string due the cumulative influence of such minor temperature differences. VRLA cells and monoblocs in which positive grid corrosion has been designed-out as main failure mode, show a much more robust performance under these adverse conditions. View full abstract»

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  • Power MOSFET failure mechanisms

    Page(s): 499 - 502
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (612 KB) |  | HTML iconHTML  

    Power MOSFET failure mechanisms are reviewed and discussed with emphasis on the parasitic bipolar transistor (BJT) turn on. The first two failure mechanisms reviewed result from high dVDS/dt. The third failure mechanism results from the slow reverse recovery of the MOSFET body diode and the fourth is a single event breakdown due to inadequate voltage derating of the MOSFET. A condition for the parasitic BJT turn on is derived and used to discuss the failure mechanisms. View full abstract»

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  • 3 kW in 60% less space: design of high power density telecommunications rectifiers with improved reliability

    Page(s): 379 - 384
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (754 KB) |  | HTML iconHTML  

    Due to increase in the floor space cost, rectifiers and other telecommunication gear, are getting smaller. Designing smaller rectifiers is not a simple task. Several design criteria must be simultaneously satisfied. These include creepages and clearances, EMC, thermal design, effects of fan forced cooling on reliability, cost and use of industry standard components. This paper discusses design challenges in the area of thermal design, and robustness to dust and airborne contaminants which can often be corrosive. Finally, it shows a practical application of these design techniques into a high reliability 3 kW telecommunications rectifier with a power density exceeding 10 W/in3. View full abstract»

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  • Low cost lithium-ion batteries for cable TV/telecom power backup

    Page(s): 155 - 158
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB) |  | HTML iconHTML  

    Modular energy devices, Inc has developed 80 Ah Li-ion battery modules having the nominal voltages of 11 V and 14 V for configuring cable TV/telecom power backup batteries. The modules are constructed from small, highly reliable, affordable and safe Li-ion cells using a proprietary electronic technology called the massively parallel modular architecture. The battery modules are readily combined in series and parallel to produce 24, 36 and 48 and 96 V battery packs configured for a wide range of capacities from 25 to 300 Ah for cable TV/telecom power backup. The use of small cells in combination with the superior electronic architecture makes the high energy battery packs safe, reliable and low cost. The design and preliminary performance data for a 36 V/160 Ah cable TV battery, CTV 100, installed in a customer facility are reported. These batteries with a nominal energy content of 5.8 kWh are drop-in replacements for the lead-acid batteries and provide up to four times longer power backup than lead-acid in the same battery enclosure over the -20 to 60°C range. View full abstract»

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  • Reliability and availability comparison of energy chain architectures

    Page(s): 554 - 560
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    Reliability and availability calculation is a useful method used for energy chain architectures comparisons. In this work, a VRLA battery reliability taking into account age, working temperature, floating voltage regulation, and autonomy of the battery strings, is proposed. Others components failures rates are gathered from the field. Then an availability calculation program for architectures, with and without generator, is developed. This program takes into account the used battery autonomy and the maintenance conditions of the energy station. Finally, reliability data with high level of inaccuracy are adjusted to fit observed unavailability results, during a five year period on France telecom energy station population. Based on this program, a sensibility study is done to determine the influence of the battery autonomy and the maintenance conditions. Finally, battery autonomy rules are derived from this study, to fulfill a very common unavailability target of 5 mn/year with the minimum of maintenance conditions. The necessity for a back-up generator with a switchover system is also discussed depending on site power AC grid quality. View full abstract»

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  • Power factor correction using CSC converter

    Page(s): 117 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (670 KB) |  | HTML iconHTML  

    The single-phase power factor correction using a buck boost type converter can control the output voltage over a wide range, because it has the ability to step-up and step-down the output voltage. Firstly, this paper compares the mechanisms of power transmission and the characteristics based on power transmission flow chart of various converters. Secondly, various chopper circuits are applied to a single-phase power factor correction, it is found that a CSC converter is suitable for such a circuit. View full abstract»

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  • VRLA battery development and reliability considerations

    Page(s): 296 - 300
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (666 KB) |  | HTML iconHTML  

    Given the wide scale acceptance of VRLA battery in standby usage, efforts to improve its reliability has been a continuous endeavor. This effort received a large impetus from the several catastrophic and well-publicized incidents with VRLA installations in the early stages, which did however allow an insight into the root causes of battery failure. The main focus of the development work has been on these root causes: more corrosion resistant grid and strap alloy, superior absorbent glass mat separator, compression issues in cell design and the need to use pure components for minimizing side reactions that lead to early failure. Improvements in these areas together with attention to battery layout within the cabinets where they were deployed and providing electronic controls are now resulting in a vastly superior VRLA experience for standby applications. View full abstract»

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  • High reliability-low cost outdoor battery enclosure

    Page(s): 429 - 436
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1057 KB) |  | HTML iconHTML  

    Growth in the outside plant equipment has prompted a demand for longer battery backup which is met by an outdoor battery enclosure (OBE). Maximizing battery life with minimum maintenance is the objective for every provider. This work presents factors affecting the design and specific requirements for a high reliability and low cost battery enclosure. The design process to develop such an OBE is described in detail. Requirements for compliance to safety and regulatory standards are also explained. View full abstract»

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  • Identification and analysis of nonlinear phenomena in boost PFC converter using bifurcation maps

    Page(s): 705 - 712
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (909 KB) |  | HTML iconHTML  

    Power-factor-correction (PFC) boost converter is the common choice for a pure sinusoidal current with a near unity power factor. The dynamics of PFC converter can be periodic with line frequency or switching frequency. This paper describes low-frequency instability, which has the practical effect on power factor values. The converter has been controlled using a conventional average-current-mode control to operate at continuous-conduction-mode (CCM). Computer simulations based on nonlinear analysis are performed to study the system stability under the variation of some chosen parameters such as load, output capacitor and feedback gain. Also, the regions of instability phenomena of the PFC converter are delimited, which is of practical interest for engineering design. The nonlinear analysis is constructed mainly from the state-space equation averaged over the switching frequency only. Based on this analysis, new two-dimensional bifurcation maps are provided to give some general outstanding about stability conditions and to identify the stable regions in the parameters space. Moreover, these maps provide an indication about the PFC converter dynamics such as its power factor values and load regulations. Beside, a prototype design of the PFC circuit is introduced to detect these instability experimentally and confirm the simulated result. Results show a good agreement between the numerical analysis and experiment. View full abstract»

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  • Fast-charge in lithium-ion batteries for portable applications

    Page(s): 19 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (699 KB) |  | HTML iconHTML  

    Lithium-ion (Li-ion) batteries are now very common in portable electronic devices (mobile phones, portable computers and other electronic devices). Moreover, this battery technology is considered as the best option for portable telecommunications applications. The main reason is the trend to produce smaller, thinner and lighter weight products. The possibility of fast-charge is very interesting in different applications in order to minimize charging time. However, a safe fast-charge (without negative effects on battery life) requires the application of the right current rate depending on battery state, operating conditions and so fourth. In this study, several Li-ion batteries (0.7 Ah) were testing intensively at charging rates from C/3 to 1.5 C, and 23° C of environment temperature. Evolution of main parameters (battery voltage, current and temperature) were recorded. Then, data obtained were processed and analyzed to determine the effects of fast-charging on Li-ion batteries. In this paper, statistic data are represented through graphics to show main characteristics of charging process as a function of charging rate used. At the end, conclusions on recommended application range of fast-charging in low capacity Li-ion batteries are presented. View full abstract»

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  • A ZVT 48 V single-phase single-stage AC-to-DC converter

    Page(s): 46 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (639 KB) |  | HTML iconHTML  

    This work presents a pulse width modulated (PWM) high frequency (HF) transformer isolated, single-stage AC-to-DC converter with a new zero-voltage transition (ZVT) circuit. This converter integrates the front-end boost stage with the cascaded DC-to-DC bridge converter. The auxiliary circuit of this topology is placed out of the main power path and, therefore, has small power rating. Identification and analyses of all operating modes of this converter are presented. Based on these analyses design example of a 50 kHz, 48 V, 1 kW AC-to-DC converter is given. Results obtained from PSPICE simulation are presented to verify the performance of this converter. View full abstract»

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  • Ambient air cooling of electronics in an outdoor environment

    Page(s): 437 - 441
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (649 KB) |  | HTML iconHTML  

    Factors that define the outdoor environment include temperature, humidity, solar loading, UV, pollution and chemical exposures, salt, wind, rain, sleet and snow. The traditional method of ensuring a "clean" environment in outdoor electronics deployment applications is through the utilization of closed-loop systems that eliminate the exchange of outdoor air with the internally housed electronics equipment. Typical examples include a sealed enclosure with a closed loop heat exchanger or air conditioner that utilizes positive pressure to guard against ingress. This type of solution requires a tremendous amount of power and generates significant acoustical noise as well as providing above ambient temperature cooling. Telcordia developed GR-63-CORE and GR-487-CORE to define standardized methods to compare units and at times force solutions (like the use of a sealed enclosure and a heat exchanger). As a way to provide the proper level of cooling and protection for the electronics, a dual media filter system was developed that allows the use of ambient air for cooling. The primary filter media is intended for the removal of aerosol particulate, and the secondary filter media is intended for the removal of liquid vapor/mist from the aerosol. A study was conducted to compare a heat exchanger system to a dual media filter system and show that it not only provided the required cooling, but also prevented corrosion due to its ability to minimize the relative humidity and industrial pollutants. View full abstract»

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  • Working with the electricity industry in times of rapid change - a telecomms user's experience

    Page(s): 100 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB) |  | HTML iconHTML  

    The public electricity supply industry in the United Kingdom has been undergoing a period of unprecedented change. Before 1990 the industry was wholly in state hands but since then the industry has been almost entirely privatised and there has been intense activity on the merger and takeover front, with most of the industry now owned by nonUK companies. This has produced a challenging environment for large users of electricity such as British Telecommunications. As one of the largest users of electricity within the UK, it is heavily dependent upon the cooperation of the electricity industry in order to be able to deliver new telecommunications services and meet its own regulatory obligations. A particular problem area is in the provision of new or upgraded electricity supplies to its buildings, where it frequently encounters long delays. The new structure of the industry has also afforded opportunities to large users to save money. One such opportunity is triad avoidance, where money can be saved by deliberately running standby generators to support BT's own load, and thereby take pressure off the national grid system at times of high demand. At BT's largest sites, it is cost effective to run the generators manually, although a new web-based remote access system is being deployed which makes it possible to run these sites remotely. At BT's other sites, it is continuing to deploy a remote alarm and control system which enables remote running of generators, both for routine and triad avoidance running. This paper expands on these and other opportunities and problems encountered in BT's dealings with the UK electricity industry. View full abstract»

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