Pub Date : 1989-10-15DOI: 10.1109/INTLEC.1989.88279
Simon S. Woo, Y.S. Sun, H.M. Lee
The authors describe the development of a 20 kW off-line switch mode rectifier system to power a large-capacity digital switching system which is under development. The rectifier unit uses a double forward circuit topology composed of four power MOSFET modules that are controlled by pulse width modulation; this makes it possible to reduce the size and weight of magnetic components. The unit is convection-cooled and uses isolated power modules mounted on one end of a heat-pipe-type heatsink. A well-designed heatsink along with a careful choice of parts and components yields an overall efficiency of typically 90%. Four rectifier units are housed in a rack cabinet, together with a total control unit which includes distribution, protection, control, and alarm functions. This rack cabinet can be paralleled in modular fashion to any required power level, and installed along with the digital switching system in a switch room. This eliminates the need for separate power rooms and distribution busbar layouts.<>
{"title":"A -50 V/100 Amp high frequency switch mode rectifier unit and its application to digital switching system","authors":"Simon S. Woo, Y.S. Sun, H.M. Lee","doi":"10.1109/INTLEC.1989.88279","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88279","url":null,"abstract":"The authors describe the development of a 20 kW off-line switch mode rectifier system to power a large-capacity digital switching system which is under development. The rectifier unit uses a double forward circuit topology composed of four power MOSFET modules that are controlled by pulse width modulation; this makes it possible to reduce the size and weight of magnetic components. The unit is convection-cooled and uses isolated power modules mounted on one end of a heat-pipe-type heatsink. A well-designed heatsink along with a careful choice of parts and components yields an overall efficiency of typically 90%. Four rectifier units are housed in a rack cabinet, together with a total control unit which includes distribution, protection, control, and alarm functions. This rack cabinet can be paralleled in modular fashion to any required power level, and installed along with the digital switching system in a switch room. This eliminates the need for separate power rooms and distribution busbar layouts.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130875006","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88302
K. Boettger
In the larger present-day UPS (uninterruptible power supply) systems, the DC voltage lies in the region of 400 V. In such cases, transformation of mains AC voltages of 3*380 V to 3*440 V will not be necessary. DC rectification equipment of such UPS devices is therefore designed without any rectifier transformers. The advantages presented by this concept are smaller dimensions and weights, smaller losses, and lower costs. Safety aspects in such devices require the same safety precautions as do normal AC systems. Special attention must be paid to all possible faults in the DC circuit. The possibility of short-circuit to earth must be countered by additional monitoring and shut-down facilities. In the event of earthing of the neutral line in the AC system, the battery voltage will have superimposed on it an alternating voltage which will prohibit the earthing of the battery mid-point. This superimposed AC potential will change along with the phase control angle imposed on the rectifier set. Because of these superimposed potentials, alternating voltages may be transmitted capacitively to metal battery-stand frames, which may cause noticeable electrification on being touched. Typical values and corrective measures are described and discussed.<>
{"title":"UPS DC intermediate circuits without AC line separation","authors":"K. Boettger","doi":"10.1109/INTLEC.1989.88302","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88302","url":null,"abstract":"In the larger present-day UPS (uninterruptible power supply) systems, the DC voltage lies in the region of 400 V. In such cases, transformation of mains AC voltages of 3*380 V to 3*440 V will not be necessary. DC rectification equipment of such UPS devices is therefore designed without any rectifier transformers. The advantages presented by this concept are smaller dimensions and weights, smaller losses, and lower costs. Safety aspects in such devices require the same safety precautions as do normal AC systems. Special attention must be paid to all possible faults in the DC circuit. The possibility of short-circuit to earth must be countered by additional monitoring and shut-down facilities. In the event of earthing of the neutral line in the AC system, the battery voltage will have superimposed on it an alternating voltage which will prohibit the earthing of the battery mid-point. This superimposed AC potential will change along with the phase control angle imposed on the rectifier set. Because of these superimposed potentials, alternating voltages may be transmitted capacitively to metal battery-stand frames, which may cause noticeable electrification on being touched. Typical values and corrective measures are described and discussed.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116894299","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88282
Y. Nagai, Y. Tomokuni, A. Fukui, N. Matsumiya
The adoption of sealed lead-acid batteries and switching rectifier unit systems in DC power supplies (DC UPS) provided with a back-up function by a storage battery, has made it possible to realize a compact, lightweight, and maintenance-free design for DC switching power supply systems. The authors report on a method for monitoring the conditions of sealed storage batteries, which allows calculations and display of remaining battery discharge time during discharge, and also the optimum charging method of the batteries. They also give an example of the optimum configuration of a system incorporating these functions.<>
{"title":"DC switching power supply system including monitoring of the battery","authors":"Y. Nagai, Y. Tomokuni, A. Fukui, N. Matsumiya","doi":"10.1109/INTLEC.1989.88282","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88282","url":null,"abstract":"The adoption of sealed lead-acid batteries and switching rectifier unit systems in DC power supplies (DC UPS) provided with a back-up function by a storage battery, has made it possible to realize a compact, lightweight, and maintenance-free design for DC switching power supply systems. The authors report on a method for monitoring the conditions of sealed storage batteries, which allows calculations and display of remaining battery discharge time during discharge, and also the optimum charging method of the batteries. They also give an example of the optimum configuration of a system incorporating these functions.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128311459","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88283
D. Chapman
A small 1.5 kW off-line switch-mode rectifier has been developed for use in 48 V or 24 V rack power systems. The convection cooled rectifier is only 143 mm wide, 260 mm high, and 250 mm deep, and weighs only 6 kg. Two-thirds of the rectifier volume is heatsink. This has been achieved by using relatively high switching frequencies, 200 to 450 kHz for the main isolating converter and 70 kHz for the sinewave input current boost converter. Sinewave input current maximizes the use of standby generator capacity and minimizes main noise injection into the telecommunication network. The switch-mode components are housed on one printed circuit board, allowing easy access to all componentry for service. All user-required adjustments are accessible via holes through the rectifier front panel and can be adjusted without removing the rectifier from the rack.<>
{"title":"A compact 1.5 kW resonant switchmode rectifier","authors":"D. Chapman","doi":"10.1109/INTLEC.1989.88283","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88283","url":null,"abstract":"A small 1.5 kW off-line switch-mode rectifier has been developed for use in 48 V or 24 V rack power systems. The convection cooled rectifier is only 143 mm wide, 260 mm high, and 250 mm deep, and weighs only 6 kg. Two-thirds of the rectifier volume is heatsink. This has been achieved by using relatively high switching frequencies, 200 to 450 kHz for the main isolating converter and 70 kHz for the sinewave input current boost converter. Sinewave input current maximizes the use of standby generator capacity and minimizes main noise injection into the telecommunication network. The switch-mode components are housed on one printed circuit board, allowing easy access to all componentry for service. All user-required adjustments are accessible via holes through the rectifier front panel and can be adjusted without removing the rectifier from the rack.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"287 1-2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131804327","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88358
J. Kolte, H. Zirath
The authors compare three cooling systems (two airborne and one waterborne) for telephone exchanges: (1) cooling through a false floor; (2) conventional air conditioning; and (2) cooling with natural convection coils, for instance using the Ericsson cooling system ERICOOL. The waterborne natural-convection system appears to be the most advantageous. The system has the following advantages: lowest power consumption; easiest achievement of cooling reserve in case of main failure; best working environment in the switching room; greatest development potential for future electronic packaging structures with increased power densities.<>
{"title":"A system comparison between water and air-borne cooling systems for telephone exchanges","authors":"J. Kolte, H. Zirath","doi":"10.1109/INTLEC.1989.88358","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88358","url":null,"abstract":"The authors compare three cooling systems (two airborne and one waterborne) for telephone exchanges: (1) cooling through a false floor; (2) conventional air conditioning; and (2) cooling with natural convection coils, for instance using the Ericsson cooling system ERICOOL. The waterborne natural-convection system appears to be the most advantageous. The system has the following advantages: lowest power consumption; easiest achievement of cooling reserve in case of main failure; best working environment in the switching room; greatest development potential for future electronic packaging structures with increased power densities.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122681583","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88340
L. Fiorella, C. Di Miceli, T. Raimondi, C. Cutrona
The authors develop a method for creating a linearized dynamic model for a series resonant converter operating with a small-amplitude modulating signal and a modulation factor much lower than one. The model was worked out by studying the evolution of the average values of the state variables. With suitable operating conditions, this method has led to the control-to-output transfer function of the converter under study. Comparison of the theoretical results with experimental data from a low-power prototype confirms that the proposed model is well-suited to describing the physical system under the operating conditions which are of practical interest. Additionally, the experimental results have shown that the linearized model is also valid for modulation factor values close to one. A problem of theoretical rather than application interest in this continuing investigation of resonant converters regards the shift of the dominant pole when fs/fo tends towards one. This shift, which has been detected experimentally, is caused by a reduction in equivalent impedance at the rectifier output.<>
{"title":"Analysis of a series resonant converter","authors":"L. Fiorella, C. Di Miceli, T. Raimondi, C. Cutrona","doi":"10.1109/INTLEC.1989.88340","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88340","url":null,"abstract":"The authors develop a method for creating a linearized dynamic model for a series resonant converter operating with a small-amplitude modulating signal and a modulation factor much lower than one. The model was worked out by studying the evolution of the average values of the state variables. With suitable operating conditions, this method has led to the control-to-output transfer function of the converter under study. Comparison of the theoretical results with experimental data from a low-power prototype confirms that the proposed model is well-suited to describing the physical system under the operating conditions which are of practical interest. Additionally, the experimental results have shown that the linearized model is also valid for modulation factor values close to one. A problem of theoretical rather than application interest in this continuing investigation of resonant converters regards the shift of the dominant pole when fs/fo tends towards one. This shift, which has been detected experimentally, is caused by a reduction in equivalent impedance at the rectifier output.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123927085","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88264
C. P. James
In July 1983, the first microprocessor-controlled power plant was installed in a Southern Bell central office to power a Northern Telecom DMS-100 switch. Since that time, the evolution of applications for that technology has continued to expand to meet desired or forecasted requirements. The initial technology is discussed, followed by a description of second-generation units. In order to achieve objectives of almost total remote office monitoring and surveillance, a group of alarms was specified that must be issuable from every newly installed plant, regardless of vendor. This allows all engineers and operations personnel to recognize the same power alarm indications from location to location. These alarms/codes were initially developed utilizing standards from several regional documents. Further developments are also summarized with particular emphasis on the new Lorain monitor. Future prospects are also assessed.<>
{"title":"The evolution and application of microprocessor control and monitor units in the central office power equipment","authors":"C. P. James","doi":"10.1109/INTLEC.1989.88264","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88264","url":null,"abstract":"In July 1983, the first microprocessor-controlled power plant was installed in a Southern Bell central office to power a Northern Telecom DMS-100 switch. Since that time, the evolution of applications for that technology has continued to expand to meet desired or forecasted requirements. The initial technology is discussed, followed by a description of second-generation units. In order to achieve objectives of almost total remote office monitoring and surveillance, a group of alarms was specified that must be issuable from every newly installed plant, regardless of vendor. This allows all engineers and operations personnel to recognize the same power alarm indications from location to location. These alarms/codes were initially developed utilizing standards from several regional documents. Further developments are also summarized with particular emphasis on the new Lorain monitor. Future prospects are also assessed.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121064523","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88319
Y. Ohashi, Y. Kuwata, Kazuma Mizuguti
The fundamental characteristics of a newly developed series-resonant converter bypassing discharge current (SRCBDC) and of a 2.7 kW rectifier using this converter are described. The SRCBDC has significant advantages over conventional series-resonant converters and is particularly useful for application to rectifiers. The advantages of the SRCBDC are as follows. It is possible to switch at zero current, even if f/sub r/<2f/sub s/ (where f/sub r/ is the resonant frequency and f/sub s/ is the switching frequency); bypassing discharge current away from a transformer makes it possible to use MOSFETs as switching devices; switching frequency variation is less than that of a conventional series-resonant converter so it is possible to use IGBTs (insulated-gate bipolar transistors) as switching devices even if f/sub r/=100 kHz.<>
{"title":"A 100 kHz, 2.7 kW rectifier using a series-resonant converter bypassing discharge current","authors":"Y. Ohashi, Y. Kuwata, Kazuma Mizuguti","doi":"10.1109/INTLEC.1989.88319","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88319","url":null,"abstract":"The fundamental characteristics of a newly developed series-resonant converter bypassing discharge current (SRCBDC) and of a 2.7 kW rectifier using this converter are described. The SRCBDC has significant advantages over conventional series-resonant converters and is particularly useful for application to rectifiers. The advantages of the SRCBDC are as follows. It is possible to switch at zero current, even if f/sub r/<2f/sub s/ (where f/sub r/ is the resonant frequency and f/sub s/ is the switching frequency); bypassing discharge current away from a transformer makes it possible to use MOSFETs as switching devices; switching frequency variation is less than that of a conventional series-resonant converter so it is possible to use IGBTs (insulated-gate bipolar transistors) as switching devices even if f/sub r/=100 kHz.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115909172","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88257
V. Visnjevac, D. Milasin, I. Traljic, A. Salihbegovic
A local area network (LAN) was developed to connect the distributed parts of power plant process control systems. The following requirements had to be met: fast transfer of short messages (alarms); transfer of long messages with high throughput; reliable transfer of data in harsh environments; and access to shared resources for all participants in process control. Performance measurements were carried out. Results indicate that in the network configuration of four stations, for maximum throughput of SDN (send data with no acknowledge) services the channel efficiency is 60%, while for SDA (send data with acknowledge) services it is 35%.<>
{"title":"Performance estimation of a token bus industrial local area network","authors":"V. Visnjevac, D. Milasin, I. Traljic, A. Salihbegovic","doi":"10.1109/INTLEC.1989.88257","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88257","url":null,"abstract":"A local area network (LAN) was developed to connect the distributed parts of power plant process control systems. The following requirements had to be met: fast transfer of short messages (alarms); transfer of long messages with high throughput; reliable transfer of data in harsh environments; and access to shared resources for all participants in process control. Performance measurements were carried out. Results indicate that in the network configuration of four stations, for maximum throughput of SDN (send data with no acknowledge) services the channel efficiency is 60%, while for SDA (send data with acknowledge) services it is 35%.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116175718","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 : 1989-10-15DOI: 10.1109/INTLEC.1989.88347
M. Yoshimura, N. Ito
Effective diagnosis methods to improve the efficiency and accuracy of air-conditioning equipment maintenance work developed at NTT are described. These methods consist of the refrigerant cycle diagnosis of air-conditioners and the deterioration diagnosis of pumps and ventilators. These technologies reduce manpower requirements and improve the accuracy of maintenance work on air-conditioning systems.<>
{"title":"Effective diagnosis methods for air-conditioning equipment in telecommunications buildings","authors":"M. Yoshimura, N. Ito","doi":"10.1109/INTLEC.1989.88347","DOIUrl":"https://doi.org/10.1109/INTLEC.1989.88347","url":null,"abstract":"Effective diagnosis methods to improve the efficiency and accuracy of air-conditioning equipment maintenance work developed at NTT are described. These methods consist of the refrigerant cycle diagnosis of air-conditioners and the deterioration diagnosis of pumps and ventilators. These technologies reduce manpower requirements and improve the accuracy of maintenance work on air-conditioning systems.<<ETX>>","PeriodicalId":272740,"journal":{"name":"Conference Proceedings., Eleventh International Telecommunications Energy Conference","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127034154","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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