Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22373
M. Nakao, H. Hayama, T. Uekusa
The evaluation of air-flow systems for telecommunication equipment rooms was carried out experimentally. Parameters were room air temperature distribution and ambient temperature of electric parts, i.e. air temperature around circuit boards, which are influenced by an air-flow system. The under-floor air supply and overhead return system has shown to be superior to other flow systems and its allowable average heat density was up to 1.1 kW/m/sup 2/. A microcomputer control unit was developed for the cooling unit. It is shown that this control can optimize the refrigeration cycle of the cooling unit under low outdoor air temperature, minimizing running costs.<>
{"title":"An efficient cooling system for telecommunication equipment rooms","authors":"M. Nakao, H. Hayama, T. Uekusa","doi":"10.1109/INTLEC.1988.22373","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22373","url":null,"abstract":"The evaluation of air-flow systems for telecommunication equipment rooms was carried out experimentally. Parameters were room air temperature distribution and ambient temperature of electric parts, i.e. air temperature around circuit boards, which are influenced by an air-flow system. The under-floor air supply and overhead return system has shown to be superior to other flow systems and its allowable average heat density was up to 1.1 kW/m/sup 2/. A microcomputer control unit was developed for the cooling unit. It is shown that this control can optimize the refrigeration cycle of the cooling unit under low outdoor air temperature, minimizing running costs.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115593918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22387
F. Ekelund
A switch-mode rectifier designed with a built-in microprocessor has been developed. This rectifier is custom-made to fit into a power plant that is controlled and supervised by a computer system. It operates with high efficiency, no audible noise, high power factor, sinusoidal input current, and low electrical noise. The microprocessor can also be used to facilitate production testing of the rectifier as well as power plant testing and operation. The rectifier ratings are an input of 208-204 V single-phase, a power factor of 0.99 at full load, and an output of 48 V (adjustable 40-57 V), 28 A.<>
{"title":"A rectifier with an internal microprocessor, that is an essential part of a very flexible, computer controlled power system","authors":"F. Ekelund","doi":"10.1109/INTLEC.1988.22387","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22387","url":null,"abstract":"A switch-mode rectifier designed with a built-in microprocessor has been developed. This rectifier is custom-made to fit into a power plant that is controlled and supervised by a computer system. It operates with high efficiency, no audible noise, high power factor, sinusoidal input current, and low electrical noise. The microprocessor can also be used to facilitate production testing of the rectifier as well as power plant testing and operation. The rectifier ratings are an input of 208-204 V single-phase, a power factor of 0.99 at full load, and an output of 48 V (adjustable 40-57 V), 28 A.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123001582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22354
D. Sable, R. Ridley
The design of a high-frequency, multimodule boost regulator suitable for use as a spacecraft battery discharger is presented. A combination of AC inductor current feedback and current-injection (DC switch current feedback) is used for optimum dynamic performance, overload protection, noise immunity, and current sharing of the modules. By suitable design of the second stage output filter, it is shown that the output impedance characteristic possesses a resonant notch instead of a resonant peak and can ensure system stability over a wide range of complex load conditions. Both the overall loop gain and the outer loop gain must be viewed to fully understand all system dynamics.<>
{"title":"A high frequency, multi-module, spacecraft boost regulator","authors":"D. Sable, R. Ridley","doi":"10.1109/INTLEC.1988.22354","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22354","url":null,"abstract":"The design of a high-frequency, multimodule boost regulator suitable for use as a spacecraft battery discharger is presented. A combination of AC inductor current feedback and current-injection (DC switch current feedback) is used for optimum dynamic performance, overload protection, noise immunity, and current sharing of the modules. By suitable design of the second stage output filter, it is shown that the output impedance characteristic possesses a resonant notch instead of a resonant peak and can ensure system stability over a wide range of complex load conditions. Both the overall loop gain and the outer loop gain must be viewed to fully understand all system dynamics.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122033678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22393
T. R. Bartholf
The author considers the economic evaluation of eight commonly used power system designs for remote locations. These designs are based on the following power-plant configurations: diesel engine generator, thermal electric generator, closed-cycle vapor turbine, solar electric generator, wind energy conversion system, solar hybrid (PV/diesel), wind hybrid (wind/diesel), and solar/wind hybrid. This evaluation provides a guideline for system design economics by comparing the results from each of the two sample cases. From these figures, a cost-to-load ($/W) ratio is calculated for each of the eight power-supply options.<>
{"title":"An economic analysis of power system designs for remote site telecommunications applications","authors":"T. R. Bartholf","doi":"10.1109/INTLEC.1988.22393","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22393","url":null,"abstract":"The author considers the economic evaluation of eight commonly used power system designs for remote locations. These designs are based on the following power-plant configurations: diesel engine generator, thermal electric generator, closed-cycle vapor turbine, solar electric generator, wind energy conversion system, solar hybrid (PV/diesel), wind hybrid (wind/diesel), and solar/wind hybrid. This evaluation provides a guideline for system design economics by comparing the results from each of the two sample cases. From these figures, a cost-to-load ($/W) ratio is calculated for each of the eight power-supply options.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125391301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22372
A. Malhammar
The latest development in natural convection theory has made it possible to predict the heat transfer coefficient for cases where an air channel, a 'chimney', is located above parallel warm plates. If this theory is applied to a cabinet filled with printed circuit boards (PCBs), it is possible to define three thermal quantities: the thermal efficiency, the heat area ratio, and the surface heat load ratio. If cabinets with different approaches in the thermal design, such as serial and parallel cooling, are compared, it is found that the thermal efficiency is about the same. The surface heat load ratio is, however, superior for the parallel cooling approach, making it suitable for PCBs with high heat loads.<>
{"title":"The thermal efficiency of cabinets cooled by natural convection","authors":"A. Malhammar","doi":"10.1109/INTLEC.1988.22372","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22372","url":null,"abstract":"The latest development in natural convection theory has made it possible to predict the heat transfer coefficient for cases where an air channel, a 'chimney', is located above parallel warm plates. If this theory is applied to a cabinet filled with printed circuit boards (PCBs), it is possible to define three thermal quantities: the thermal efficiency, the heat area ratio, and the surface heat load ratio. If cabinets with different approaches in the thermal design, such as serial and parallel cooling, are compared, it is found that the thermal efficiency is about the same. The surface heat load ratio is, however, superior for the parallel cooling approach, making it suitable for PCBs with high heat loads.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125262221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22367
G. Moore, W. Peterson
A solar photovoltaic (PV) thermoelectric generator (TEG) hybrid system combines the economics of a solar photovoltaic system with the reliability and heating capability of a thermoelectric generator system. The solar system provides power during seasons with abundant sunshine while the thermoelectric generator system provides power and heat as required during seasons with insufficient solar insolation or during extended periods of inclement weather. The author discusses the principle of operation of a thermoelectric generator and solar PV-TEG hybrid system, and examines two existing sites in northern Canada. It is concluded that, to obtain maximum reliability and still remain cost-effective, the design of a remote power system must be tailored closely to individual site requirements, location, and ambient temperatures. It has been found that at locations where delivered fuel costs become significant and stand-alone solar is not a viable alternative, a solar PV-TEG hybrid system can provide unmatched reliability and economics.<>
{"title":"Solar PV-thermoelectric generator hybrid system: case studies","authors":"G. Moore, W. Peterson","doi":"10.1109/INTLEC.1988.22367","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22367","url":null,"abstract":"A solar photovoltaic (PV) thermoelectric generator (TEG) hybrid system combines the economics of a solar photovoltaic system with the reliability and heating capability of a thermoelectric generator system. The solar system provides power during seasons with abundant sunshine while the thermoelectric generator system provides power and heat as required during seasons with insufficient solar insolation or during extended periods of inclement weather. The author discusses the principle of operation of a thermoelectric generator and solar PV-TEG hybrid system, and examines two existing sites in northern Canada. It is concluded that, to obtain maximum reliability and still remain cost-effective, the design of a remote power system must be tailored closely to individual site requirements, location, and ambient temperatures. It has been found that at locations where delivered fuel costs become significant and stand-alone solar is not a viable alternative, a solar PV-TEG hybrid system can provide unmatched reliability and economics.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"35 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133036594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22319
T. Sugiura, T. Ogata, T. Koyashiri
The authors describe the state of ISDN (integrated services digital network) services in Japan and discuss issues concerning power supply systems suitable for the ISDN age. A distributed power supply system has been developed to solve the problems posed by centralized systems in telephone offices when ISDN systems are adopted. A compact, thin board-mounted DC-DC converter for a digital switch system has been developed. In addition, a small-size constant-current DC-DC converter has been developed for the metallic subscriber-loop system. A small-capacity uninterruptible power unit with back-up batteries, for use on subscriber's premises, has been developed for the optical-fiber subscriber loop systems. An extremely lightweight, high-voltage DC-DC converter for a communications satellite has also been developed.<>
{"title":"The impact of ISDN on Japan's telecommunications power system","authors":"T. Sugiura, T. Ogata, T. Koyashiri","doi":"10.1109/INTLEC.1988.22319","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22319","url":null,"abstract":"The authors describe the state of ISDN (integrated services digital network) services in Japan and discuss issues concerning power supply systems suitable for the ISDN age. A distributed power supply system has been developed to solve the problems posed by centralized systems in telephone offices when ISDN systems are adopted. A compact, thin board-mounted DC-DC converter for a digital switch system has been developed. In addition, a small-size constant-current DC-DC converter has been developed for the metallic subscriber-loop system. A small-capacity uninterruptible power unit with back-up batteries, for use on subscriber's premises, has been developed for the optical-fiber subscriber loop systems. An extremely lightweight, high-voltage DC-DC converter for a communications satellite has also been developed.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127158670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22347
R. M. Welch
The 'worth of a watt' concept deals with the cumulative operating expense associated with consuming one AC watt of power at any point in a central office power processing chain. Here, the worth of a watt concept is extended from central office power systems to power systems in 'confined locations' i.e., small above-ground or below-ground electronic equipment enclosures, that house loop and interoffice electronic equipment. Also considered are changes that have occurred during the period 1978 to 1988 in the present cost and inflation rate for AC power costs, in corporate income tax rates, and in the economic life of power equipment. The net effect of these changes is that the worth of a watt has increased much less than might be expected from the increases in the cost of commercial AC power over the decade. The implications for both designers and users are explored.<>
{"title":"Worth of a watt for power systems in digital loop carrier and other remote locations","authors":"R. M. Welch","doi":"10.1109/INTLEC.1988.22347","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22347","url":null,"abstract":"The 'worth of a watt' concept deals with the cumulative operating expense associated with consuming one AC watt of power at any point in a central office power processing chain. Here, the worth of a watt concept is extended from central office power systems to power systems in 'confined locations' i.e., small above-ground or below-ground electronic equipment enclosures, that house loop and interoffice electronic equipment. Also considered are changes that have occurred during the period 1978 to 1988 in the present cost and inflation rate for AC power costs, in corporate income tax rates, and in the economic life of power equipment. The net effect of these changes is that the worth of a watt has increased much less than might be expected from the increases in the cost of commercial AC power over the decade. The implications for both designers and users are explored.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134055100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22377
A. Ghiraldi
The application of phase-change materials to the control of internal temperature in telecommunications equipment enclosures has resulted in the development of passive conditioning systems (PCS) which will maintain temperatures within equipment operating limits without the use of conventional air conditioning. PCS-equipped enclosures can readily protect electronic systems of up to 30 kW dissipation, and because the system is passive, the reliability of the electronic installation is that of the prime equipment rather than that of the far less reliable air-conditioning equipment. A further advantage is that, with temperatures closely controlled without air exchange from the outside environment, there is a resultant stabilization of internal humidity at acceptable levels, again without active control equipment. The basic principles of such systems are presented, and attention is given to the design philosophy, construction, the heat-exchanger option, manufacturing, and life-cycle costs.<>
{"title":"Passive conditioning systems for temperature control in telecommunications equipment enclosures","authors":"A. Ghiraldi","doi":"10.1109/INTLEC.1988.22377","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22377","url":null,"abstract":"The application of phase-change materials to the control of internal temperature in telecommunications equipment enclosures has resulted in the development of passive conditioning systems (PCS) which will maintain temperatures within equipment operating limits without the use of conventional air conditioning. PCS-equipped enclosures can readily protect electronic systems of up to 30 kW dissipation, and because the system is passive, the reliability of the electronic installation is that of the prime equipment rather than that of the far less reliable air-conditioning equipment. A further advantage is that, with temperatures closely controlled without air exchange from the outside environment, there is a resultant stabilization of internal humidity at acceptable levels, again without active control equipment. The basic principles of such systems are presented, and attention is given to the design philosophy, construction, the heat-exchanger option, manufacturing, and life-cycle costs.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128157014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-30DOI: 10.1109/INTLEC.1988.22318
G. Pagliai, M. Brambilla
The authors describe the basic nature of photovoltaic (PV) systems, the reason for PV growth in telecommunications applications and the trends of photovoltaic evolution. The development of both components and systems is discussed. Economic aspects of the use and choice of solar systems are presented by evaluating markets, equipment cost trends, and system cost variations due to different site and environment data and also to the possible system policy approaches. Topics concerning the current economic position of PV systems with respect to other power sources are included. Finally, the most important advantages of 'power mix' are described by taking hybrid power systems into consideration.<>
{"title":"Photovoltaics and TLC (telecommunication power supplies)","authors":"G. Pagliai, M. Brambilla","doi":"10.1109/INTLEC.1988.22318","DOIUrl":"https://doi.org/10.1109/INTLEC.1988.22318","url":null,"abstract":"The authors describe the basic nature of photovoltaic (PV) systems, the reason for PV growth in telecommunications applications and the trends of photovoltaic evolution. The development of both components and systems is discussed. Economic aspects of the use and choice of solar systems are presented by evaluating markets, equipment cost trends, and system cost variations due to different site and environment data and also to the possible system policy approaches. Topics concerning the current economic position of PV systems with respect to other power sources are included. Finally, the most important advantages of 'power mix' are described by taking hybrid power systems into consideration.<<ETX>>","PeriodicalId":169486,"journal":{"name":"10th International Telecommunications Energy Conference","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123080379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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