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Telecommunication - Energy Special Conference (TELESCON), 2009 4th International Conference on

Date 10-13 May 2009

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Displaying Results 1 - 25 of 31
  • ICT Getting Green

    Page(s): 1 - 6
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    It is politically correct and acceptable behaviour to resist Global Climate Change and Greenhouse Gas Emissions. Governments in Europe have set measurable targets to ecological footprints and usage of renewable energy sources. Despite of these general concerns, only few serious measures have taken place to implement these wishes in ICT sites. As a matter of fact, only few economically realistic and concrete actions have been suggested to reduce the growth of electricity consumption. Some telecom operators have set energy saving as one evaluation parameter for their new wireline and wireless infrastructure equipment. Data center owners have not paid attention to the energy consumption as much as telecom operators. ICT industry has not been among the most power consuming industries in the past, but considered as ï¿¿ï¿¿ï¿¿less than 1%ï¿¿ï¿¿ï¿¿ sector. ICT industry is quite difficult and fragmented sector to understand even to professionals from power consumption point of view. Firstly, one should understand the underlying reasoning why electricity consumption in ICT is growing nowadays over 15% year-to-year and secondly, the rapid emerge of telecom and datacom technologies to one single ICT network is blury. Thirdly, telecom and datacom engineers have traditionally understood power supply in a different manner. Power has not drawn site ownersï¿¿ï¿¿ï¿¿ primary attention since the cost of electricity has not been too high and the system reliability requirements have not been as outstanding as they are today. Powering back up and redundancy solutions as well as site powering building blocks have stayed quite the same for tens of years. Power architecture changes or introducing new technologies have not been economically meaningful. However, todayï¿¿ï¿¿ï¿¿s competition in ICT is fearce and the continuous increase of electricity costs has alerted ICT operators, data center owners and political decision makers. ICT power consumption in developed countries has been doubled in few years. It has moved- - from ï¿¿ï¿¿ï¿¿less than 1%ï¿¿ï¿¿ï¿¿ issue to ï¿¿ï¿¿ï¿¿more than 2%ï¿¿ï¿¿ï¿¿ issue from all national electricity consumption and will be doubled again within next 5 years. At the same time the price of electricity has been increasing by double digits annually, impacting very negatively to direct costs of ICT companies. This issue is today both visible and serious. There are, however, concrete means to cut the growth of electricity costs considerably, not only by using latest power technologies but introducing intelligence in power feeding modules and adopting new powering and network architectures. Further on, alternative energy sources can be applied for decentralized power feed, which at the same time can also improve the overall reliability of ICT networks. View full abstract»

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  • An Overview of Battery Development placed in a historical Context and future Aspects

    Page(s): 1 - 4
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    More than 200 years ago Luigi Galvani and Alessandro Volta evaluated the basic principles of batteries. Since those days many different types of accumulators are developed. But only three major types dominate the industrial market of secondary batteries today. This paper presents a historical overview and future aspects and trends. View full abstract»

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  • Reliable Power Supply for Remote Telecom Facilities

    Page(s): 1 - 6
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    Telecom facilities in remote areas, like repeater or cellular base stations, often cannot be powered by the electric grid. It is too expensive to build a connection or it is not ready in time. Conventional Diesel generators with standby batteries are used. This is costly and requires high maintenance. In the last years a growing number of telecom facilities use a PV panel, sometimes supported by a small wind turbine as a power source and a battery as back-up. In these applications the battery has tougher requirements as in a normal stand-by use: Every day cycling, low state of charge in winter, high over charge in summer, maintenance-free design is preferable. Test results to prove the endurance in cycles of VLA batteries according to IEC 60896-11 and of VRLA batteries according to IEC 60896-2 are presented. We also present the endurance in cycles from tubular VLA and tubular GEL VRLA batteries for the special cycles in photovoltaic systems according to the standard IEC 61427. Finally we calculate the life cycle costs of OPzS, OPzV, OGi block and AGM block for a period of 20 years. It is interesting to see, that low maintenance and high service life are the important issues for amount of the life cycle cost. View full abstract»

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  • Ohmic Testing Applications in VRLA Batteries Maintenance

    Page(s): 1 - 8
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    As a large scale Telecommunications Operator with a vast network as well as a large customer base, battery maintenance has always been an important and also a huge task for China Mobile. Traditional methods of battery maintenance have become continuously more difficult to complete due to the rapid expansion of the network infrastructure each year. Starting in 2006, China Mobile began to investigate how Ohmic testing method could play a role in easing the huge workload of battery maintenance. Hundreds of batteries in the field have been tested and results indicated that batteries manufactured in China did exhibit a correlation between Ohmic testing value and the capacity. With the conclusions drawn from the validation field tests, China Mobile started to apply the Ohmic testing technology in the practice of battery maintenance work, including using conductance testing on approval inspection before installation of new batteries. Conductance was also utilized in regular battery maintenance work, as well as the emergency patrol tests of batteries in thousands of base stations right after the occurrence of a serious catastrophe. This paper will introduce the progress that China Mobile made from the field validation tests with regard to the application of Ohmic testing value as a tool to identify the state of health of the batteries, and also the progress of China Mobile¿s application of Ohmic testing in its network, as well as some initial progress that China Mobile experienced after implementing the use of these technologies in the battery maintenance procedures. With more understanding of Ohmic testing and more confidence in the technology, Chinese telecom operators can reduce discharge testing as they gain confidence in Ohmic results over time, saving time and money. View full abstract»

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  • The Batteries¿ Regulatory Process in Brazilian Telecommunications Industry

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (137 KB)  

    The privatization of telecommunications sector in Brazil (Telebras) completed ten years in 2008. After Telebras privatizing, the Brazilian government created Anatel (Telecommunications National Agency) that is in charge of telecommunication¿s regulatory and supervisory activities. One of the activities of the Anatel is the certification and homologation of products and equipments to be used in the Brazilian¿s telecommunication network. The objective of this paper is to describe and discusses the requirements and tests specified in each ¿Resolution¿ (Anatel¿s standards) for lead acid stationary batteries, portable battery and also to present the CPqD¿s laboratories activities in this area. View full abstract»

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  • Improving the Characteristics of Lithium-ion Cells by Applying a Heat-resistant Separator and Heat Conductor

    Page(s): 1 - 7
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    In recent years, industrial lithium-ion cells have been developed that are capable of being used as backup power supplies in systems such as communication equipment, and are expected to contribute to reducing the size of backup storage batteries in many applications. For these applications, backup storage batteries must have a long lifetime and must remain safe even in unforeseen circumstances. To make lithium-ion cells safer to use, we have develop a lithium-ion cell separator with a higher breakdown temperature, and we verify the effects of this improvement. We also propose incorporating a heat conductor into the interior of the cell, and we verify its effects on the overcharging characteristics of lithium-ion cells with a nominal capacity of 40 Ah. Our results demonstrate that improving the separator breakdown temperature and installing a heat conductor can effectively improve the cell safety without any significant detriment to the cell characteristics. View full abstract»

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  • Variable Voltage PSU Technology for ICT Applications

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (862 KB)  

    ICT power supply systems are facing considerable challenges in the future. Especially in the datacom applications power demand has been rising on continuous basis. At the same time the pressure generated by rising energy cost and global need to minimize the greenhouse effect is getting heavy. Therefore, energy efficiency of ICT power supply systems must be considered carefully so that the ecological footprint can be kept tolerable also in the future. In order to achieve the goal of minimized negative environmental impact of ICT power systems, the following issues must be considered: power system architecture, load management and efficiency of each power system element. Increasing power system efficiency is the best near term means to solve the challenge of rising cost and green house gas emissions. This paper concentrates on novel power supply unit (PSU) technology developed for this purpose. One viable possibility to cut energy consumption of ICT loads is to control the supply voltage of the load devices according to the actual operating state of the unit. In datacom systems this means scaling the processor system supply voltage according to the actual operating mode (e.g. idle, sleep mode, 50 % processing capacity and full power). The same principle can be utilized also in cellular network applications, especially in RF amplifiers for base tranceiver stations (BTS). Two PSU technology options are available depending on the dynamical needs of load voltage control. Average power tracking power supply is based on rapid switching between predefined output voltage levels according to the actual load demand. In envelope tracking method the output voltage of the PSU dynamically follows the required signal envelope waveform. It has been proved that variable voltage PSU technology can provide considerable increase in efficiency of RF power amplifiers. On the other hand, variable supply voltage can have effect on other operational characteristics of the system and challenge- - s in e.g. amplifier linearization can occur. Therefore, close co-operation between the power supply and load electronics designers is necessary in order to achieve an optimized solution. View full abstract»

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  • A Study of High Voltage Converter Topologies with Wide Input Voltage Range

    Page(s): 1 - 8
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    The Power Processing Control Unit (PPCU) is one of the components of the power supply system, and it consists of eight power supplies for a beam converter, an accelerator converter, a discharge converter, two hollow-cathode keeper converters, two hollow cathode heater converters, and an auxiliary converter. The beam converter output voltage level is less than +1100V and the accelerator converter output voltage level is more than -550V. The PPCU is required to achieve high power efficiency with wide input voltage range (32.5V to 50V) as well as to minimize volume, to reduce weight and to suppress the electromagnetic interference. The power efficiency target of the high voltage converter is more than 90% for nominal 500W at input voltage between 32.5V to 50 V.The PPCU bread-board model (BBM) consisting of the high voltage converter (a beam converter and an accelerator converter) was manufactured for the ion engine system. We examined the power converter topologies to solve the issue of achieving light weight and high power efficiency. We selected the inductor-fed phase shift converter and the vector combined voltage resonant converter. These two kinds of power converter were tested in order to evaluate the converter performance, especially power efficiency. The results show that the power efficiency of the vector combined voltage resonant converter is better than the inductor-fed phase shift converter. The power efficiency is more than 90.7%, and so we select the vector combined voltage resonant converter of high voltage converter topologies. View full abstract»

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  • Method of Designing a Four-Legged Transformer for Hybrid-Type DC-DC Converters

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1681 KB)  

    An integration of an output choke with a transformer has been attempted to miniaturization of forward converter. For example, a forward active clamp topology using a four-legged core has been proposed. This paper proposes a design methodology for this four-legged transformer. By means of an analysis, it was found that the magnetic flux in the leg, which acts as a output choke, has both dc and ac component. When the core of a transformer was designed using the proposed method, it was possible to reduce the footprint of the magnetic device in comparing with that of a conventional converter. View full abstract»

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  • Improved PFC Circuit for Three-Phase Single Switch Having Auxiliary Capacitors

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2253 KB)  

    Nonlinear rectifier circuits, having capacitors or inductors, are generally used as rectifier circuits, such as those in consumer electronics and appliances. It is known that such rectifiers generate various harmonics in the power system. To reduce these harmonic problems, various original PFC (Power Factor Correction) circuits have been proposed. Amongst these, Prasad-Ziogas, et al, have proposed a PFC scheme using single switching device for three phase circuit applications. This method achieves a PFC effect by simultaneously creating three phase supplies by the use of a single switch through an inductor. On the basis of this scheme, we propose an alternative PFC circuit. This method attempts to improve the input current, approaching a nearly sinusoidal waveform, by using an intermediate capacitor circuit, with a method of operation analogous to the conventional method having capacitor filter, but is, nonetheless, original. Various fundamental operations have been considered and have been confirmed by computer simulation. Compared with the conventional Prasad-Ziogas circuits, the construction is a little more complicated, but the output power can be much increased, in addition to improved THD (Total Harmonic Distortion). View full abstract»

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  • Uninterrupted power supply - supported by fuel cells

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (902 KB)  

    Uninterrupted power supply systems (UPS) for telecommunication are already under discussion both for centralized applications as well as for decentralized applications. Remote repeater stations which have an electrical consumption of less than 750 Wel are more and more equipped with UPS systems based on either batteries or super capacitors. With decreasing reliability of electric mains the length of power outages is increasing. The more telecommunication is a necessary part of everyday life the more rises the demand for long term power backup of the telecommunication networks. Using hydrogen powered fuel cells as long term energy source in addition to short term storage devices such as super capacitors is an environmentally and economically interesting option for decentralized backup systems. In this paper a solution for an outdoor cabinet integrated fuel cell powered UPS is described. The system architecture is optimized for traffic components but is already including the classic power supply technologies for telecommunication applications. View full abstract»

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  • Fuel Cell Back-up Power

    Page(s): 1 - 2
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    The need for reliable backup power has never been greater than in today's always connected and on-demand world. Fuel cells can provide the solid-state backup power solutions that are needed in this new power paradigm. Fuel cells offer improved system reliability, more predictable performance in a broad range of climates and a reliable service life when compared to the industry standard valve regulated lead acid (VRLA) battery strings. Life cycle costs are also reduced because of greatly decreased maintenance and replacements needs. Finally, fuel cells also offer strategic environmental advantages to end users because disposal costs and liability risks related to lead acid batteries are an increasing concern. Unlike batteries (energy storage), Fuel cell is a "clean" power generator which is also an alternative to diesel generators when long autonomy is required. View full abstract»

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  • Novel Voltage Balancer for an Electric Double Layer Capacitor by using Forward Converter

    Page(s): 1 - 6
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    EDLCs (Electric Double Layer Capacitors) offer high energy density and long life span, so various applications may be anticipated in the realm of energy storage devices, such as those used in electric vehicles or electric power stabilisation in power systems, etc. However, since the voltage limit of the devices is low, it is necessary to connect them in series or parallel. In addition, it is required that they be used in the region of their critical voltage or capacity limits. In order to apply them efficiently, the devices should be used with balanced voltage. Firstly, the authors discuss a conventional method, using a forward converter, and then propose a modified novel simple solution. Characteristics of the proposed circuit are analized and discussed. View full abstract»

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  • Investigation into technical factors related to stationary lithium-ion battery used in telecommunications applications

    Page(s): 1 - 5
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    Today, lead-acid batteries are the most common choice for battery backup of communication equipment power systems. In recent years, however, a demand for a more compact power supply is growing amid expectations for spreading use of the NGN. Lithium ion batteries, which feature high energy density, are expected to greatly contribute to such reduction of power supply size. Improved safety and longer lifetime are indispensable for use of lithium ion batteries in power supply facilities for communication equipment. When manganese-based active material is used for the positive material, manganese eluted from the positive electrode migrates to the negative electrode surface, where it reacts with lithium ions to deactivate the lithium. That phenomenon has been confirmed to decrease battery capacity. Therefore, to extend battery life, we investigated the elution characteristics of manganese ions from the positive electrode by using test samples in which the elemental manganese of the positive material is partially replaced with some other metal element. The results show that there is least elution of manganese from the positive electrodes of lithium ion batteries that use manganese-based pasitive materials when the manganese is replaced by magnesium. With the objective of higher battery safety, we also investigated the elution characteristics of manganese ions from the positive electrode for when a phosphazene-based flame retardant has added to the electrolyte solution. The results show that the flame retardant in electrolyte decomposes during long-term storage to generate fluorine compounds, which have been confirmed to accelerate the elution of manganese ions. We also learned that decomposition of the flame retardant is related to the stability of the electrolyte, so elution of the manganese ion can be controlled by using a stable electrolyte. View full abstract»

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  • Increasing Grid Transmission Capacity and Power Quality by new Solar Inverter Concept and Inbuilt Data Communication

    Page(s): 1 - 5
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    Increasing regenerative power sources installed in low voltage grids tend to cause overvoltage problems due to the reverse power flow direction. Consequently, regenerative sources need to be turned off temporarily or on the long term, the grid infrastrucutre would have to be extended by the utility company. Additionally, the increasing number of grid connected power electronic systems causes a high level of reactive power flow and harmonics in the grid affecting power quality. The concept described in this paper uses reactive power which is generated in the solar power inverters to increase power capability of the grid. By means of additional reactive power consumption, the grid voltage can be decreased to acceptable values and stabilized. Grid extension in many cases can be avoided or, at least it can be delayed. For control of a distributed system of a number of solar inverters installed in a grid segment distributed data collection and central control is required. Data and control parameters are being transmitted over the power lines with inbuilt real time DLC (distribution line carrier) communication. Additionally, the inverters can be remotely controlled to compensate harmonic distortion and to improve phase voltage balance by feeding unsymmetrical currents into the three phases. The concept can be applied not to solar power systems only; it is rather a basic technology which can be used in future grids with distributed generation and storage. Even the power consumption in the grid can be optimized accordingly to the generation if remotely controllable appliances will be installed in the future. With the technology shown in the paper higher reliability, increased and controllable power quality and less problems in low voltage grids can be achieved. Thus, the capability to accept, integrate and transmit higher quantities of decentralised generated power can be improved. View full abstract»

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  • Evaluation of dc Voltage Levels for Integrated Information Technology and Telecom Power Architectures

    Page(s): 1 - 7
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    This paper discusses possible dc voltage options for information technology and telecom power architectures. Instead of considering an adaptation of existing architectures, it contemplates design factors without engineering preconditions. This is a technology planning approach based on systems fundamentals. Both conventional architectures and microgrid-based designs are discussed. The study reveals that there exist many tradeoffs which yield no particular best option. A compromise solution with a ± 150 V split phase microgrid-based architecture and a corresponding multiple-input SEPIC converter are also introduced in this paper. View full abstract»

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  • Scientific methodology for Telecom services energy consumption and CO2 emission assessment including negative and positive impacts

    Page(s): 1 - 14
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    The France Telecom operator is highly involved in environmental preservation and part of it, is the scientific studies of ICT impacts associated with an active contribution to standardization bodies, observatories, groups, fora and initiatives such as ETSI and ITU-T. This paper describes France Telecom and university common research work in this field and how it can help standardization works. All these methods will help to determine holistic negative impact of ICT, but also the positive impact by dematerialization in a realistic way. Then it is possible to calculate the balance and the so-wished gain by using ICT. The paper will also compare the different Key Performance Indicators that can be calculated by using the impact results such as ICT power consumption reduction, ICT gain on other sectors, ICT contribution to the effort on global consumption and CO2 reduction targets. Finally, the paper should not be complete without indicating some new paradoxes that need much more studies: intensity decrease may hide an absolute value increase, manufacturing optimization and green label may increase the global consumption, the sustainable development level can limit the absolute reduction. View full abstract»

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  • Site Power Saving

    Page(s): 1 - 5
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    The solution Site Power Saving, adopted in Telecom Italia by using Ericsson Technology, addresses the Company need of power consumption management optimization on BTS sites. View full abstract»

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  • A New Multi-Loop Digital Control DC-DC Converter

    Page(s): 1 - 5
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    This paper presents a new multi-loop digital control circuit which is able to detect not only the average output voltage but also the output current and input voltage of the dc-dc converter. The proposed digital control circuit consists of the three A-D converters, one DSP and the digital PWM circuit. In this proposed digital control circuit, the output voltage is used for the digital P-I-D control, the load resistance is calculated using the output voltage and current and then the moving average of the load resistance is obtained for another control loop. As a result, it is clarified that the transient time is suppressed to within 1.15ms and this result is approximately 84% smaller than the conventional static model controlled dc-dc converter. Especially, the overshoot of reactor current is suppressed to within 68% and this result is approximately 50% smaller than that of the conventional control method. It is confirmed that the proposed multi-loop control technique is useful to realize the high performance digital control circuit of dc-dc converter. View full abstract»

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  • Efficient powering of communication and IT equipments using rotating UPS

    Page(s): 1 - 5
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    Today, the demand for uninterrupted power supply for Telecommunication and Internet services increases drastically. Following the same trend, cooling demand explodes. Supplying sufficient power with extremely high reliability becomes even more challenging. The era of telephone exchanges using 48V power supply and 8 hours of battery backup is past. Telecom Operators are currently migrating from POTS to all IP. In addition, broadband Internet access for everyone using DSL or fibre is already reality. More and more applications like TV on demand, streaming services, online gaming or entertainment are very power hungry. For such large systems, static UPS systems are no more efficient. A better alternative is offered by rotating UPS, also known as "No-break". In addition to requiring less space and no batteries, these systems have a better power efficiency too. View full abstract»

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  • Increased MTBF and Decreased Maintenance Cost by using systems without fans

    Page(s): 1 - 5
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    This paper describes the advantages of power supply without fan in telecommunication systems. Reliability engineering focuses on design rules using high quality components and avoiding components with lifetimes shorter than service life of the power supply system. Convection cooling avoids high temperature levels, high temperature rise and too compact design. The focus is low maintenance effort, long service life, low stress, moderate utilization for general long life time. For these applications Gustav Klein has developed power system solutions with no need of regular maintenance within lifetime. Natural cooled Rectifiers, Inverters, DC/DC-Converters, Frequency-Converters and Uninterruptable Power Supplies are available up to 80kW respectively 80kVA. Natural cooled Power Supplies needs more powerful components, but a smaller quantity. The low quantity of components and the low temperatures increases the MTBF. Convection cooling uses low air speeds and needs in most applications no filtered air. Heat sinks with low temperature differences are in full operation even when they are covered with dust. So maintenance effort is in most applications a simple visual check. View full abstract»

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  • Fuel-Cells in the required packaging

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (231 KB)  

    One of the major properties of a commercial fuel-cell-system is the right packaging for the provided operational environment. The following description explains the needs and experiences for such applications in indoor and outdoor environments. View full abstract»

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  • Overview to ETSI Standards and Guides for Efficient Powering of Telecommunication and Datacom Equipm ent and Building

    Page(s): 1 - 6
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    Telecommunications networks worldwide are evolving rapidly into systems carrying over the broadband services with Internet, cable TV and other data traffic in addition to traditional voice telephony, and operators are seeing a large increase in Internet equipment installed in their networks. This development has influence to the actual existing standards for the power supply interfaces. European Telecommunication Standardization Institute (ETSI) is the regional organization that is recognized by the EC and EFTA as one of the three official standards-making bodies in Europe, and is responsible for standardization in the whole field of telecommunications, including radio, broadcasting and private telecommunications. The requirements for the power distribution to the interface ¿A" for -48V/-60V are standardized in the ETSI EN 300 132-2. The mixing of the traditional telecommunication equipment with new broadband and IT equipment in the Central Office (CO) and access network need a solution for the powering and safe installation (earthing, grounding, batteries) with higher efficiency and reliability. In the year 2003 was published the ETSI EN 300 132-3 for direct powering the transmission equipment with 400 V. In several workshops on the INTELEC 2003, 2004, 2005, 2006, 2007 and 2008 and worldwide initiatives were discussed the different experiences and solutions in connection to several pilot projects. A wide use of DC in electrical installations offers high energy efficiency, and improves power quality in the AC distribution network. The presentation will give a small overview to the standardization in the last 6 years with the actual results, problems and trends in the worldwide realization of higher efficient powering of the new internet equipment. View full abstract»

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  • The New Product Safety Standard for Communication Tec hnology Equipment

    Page(s): 1 - 7
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    The IEC Technical Committee 108 - Safety of electronic equipment within the field of audio/video information technology and telecommunication technology - is developing an entirely new safety standard, applicable to Consumer Electronics, Information Technology Equipment and Telecommunication Equipment. The standard will be performance based and technology independent. The standard is being developed using engineering principles and will clearly identify the hazards addressed. This is a "Hazard Based Safety Engineering" concept (HBSE concept). (IEC = International Electrotechnical Commission). Between IEC TC 108 and ETSI TC SAFETY exist a liaison. This new standard is very different from previous standards. The ¿Hazard Based Standard¿ addressed all hazards, which could be present in equipment falling under the scope of this new standard IEC 62368. This presentation will be given an overview about this new standard. On the example of the protection against electric shock and chemical hazards inclusive safety requirements for batteries the hazard based concept will be discussed. The electric shock depends on various parameters and causes different reflexes of the human body. The electrical energy source is depending of different parameters of power source, such as voltage and current for dc, low and high frequencies, as well as for single pulses. The model for safety ¿ energy source => safeguard => safe human body ¿ will be in the presentation discussed. Safeguards for protection against electric shock could be insulation (Basic; supplemental, reinforced) components (e.g. transformers, capacitors, resistors) and conductors (PEconductor). Detailed requirements for the parameters of the safeguards will be given in the standard IEC 62368. The presentation will show the safety concept only. View full abstract»

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  • The Green Base Station

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    In times of steadily increasing energy costs and with the vanishing resources of the classic, non-regenerative energy sources, we see the challenge of finding new solutions for the uninterruptable power supply of mobile radio base stations (BTS). A growing environmental consciousness and the demand for reduction of the emission of greenhouse gases like CO2 increase the motivation to develop alternative power supply concepts. The paper introduces a concept: how to feed a BTS with all known suitable power supply technologies, including PEM fuel cell, wind power, photovoltaic power and high-efficiency-power conversion technology. The application of these building blocks can be adapted individually to the local environmental conditions and requirements. These technologies also offer the possibility to build up mobile radio base stations in locations that are miles away from the public mains grid (off-grid). The Green Base Station which is introduced is equipped with the regenerative energy sources wind power and photo-voltaic energy to reduce the power consumption taken out of the public grid to a minimum, whenever sunlight or wind is present. During operation times when wind power and solar energy are not sufficient to feed the BTS, additional energy is taken out of the public mains grid. High-efficiency rectifier modules convert the mains AC to a 48V DC voltage for the radio equipment. High-efficiency technology reduces losses of the AC/DC and DC/DC power conversion to a minimum and also contributes to the reduction of the requested air conditioning power. A Free-Cooling air conditioning system reduces the energy consumption of the base station additionally, in comparison to traditional solutions. If all of the mentioned power sources fail or cannot provide the total requested power of the BTS equipment, an additionally installed PEM fuel cell starts up automatically. The PEM fuel cell is able to provide long backup times with minimal space demand and low weight. The - - fuel cell does not produce hazardous emissions and acoustic noise like traditional diesel generators. Only a small backup battery is used during the start-up time of the fuel cell. Thus, the amount of lead is reduced to a minimum in the Green Base Station. Depending on the system configuration, it is even possible to completely avoid the usage of lead acid batteries. The pros and cons of the Green Base Station concept will be presented and evaluated, as well as chances and challenges stated. The technology for a Green Base Station is already available, but costs and reliability are two of the most important challenges to solve before the Green Base Station can become a widespread reality. View full abstract»

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