{"title":"Safety of DC power equipment: past, present, and future","authors":"A.S. Ancel","doi":"10.1109/INTLEC.1994.396615","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396615","url":null,"abstract":"Product safety engineering represents the application of safety engineering rules of practice to the design and manufacture of products of all types. This paper illustrates this statement under the following topics: discussion of product safety; safety history of telecommunication DC power supply equipment; distinction between safety and safety regulations; product hazards; a \"roadmap\" to obtain product safety approvals; and future considerations.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126514390","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}
{"title":"Rectifier input current distortion-how much can be permitted? Implications of existing standards and other considerations","authors":"T. Wolpert","doi":"10.1109/INTLEC.1994.396636","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396636","url":null,"abstract":"Harmonic pollution of electrical power systems is a subject of increasing importance. Power converters are a type of load that generates current harmonics, and the designers of converter equipment are highly concerned with this problem. Two existing standards, the European EN 60 555-2 and the American IEEE Std 519 formulate the requirements on harmonic contents. This paper analyses these standards and their practical implications. It is shown that (a) there is a certain ambiguity in applying EN 60 555-2, (b) although IEEE 519 refers to the power system, not to the equipment, it is possible-by some additional analysis-to formulate the requirements on the AC/DC converter equipment, and (c) despite the differences in the approach, both standards result in similar requirements. Additional considerations are necessary to determine the allowable distortion values. One such consideration is the case of supply from an emergency set diesel engine alternator. Any rectifier design should consider the eventuality of supply from an emergency set of limited power rating. The emergency set is a soft source with high internal impedance. In this case rectifier current harmonics can cause excessive voltage harmonics in the AC distribution, resulting in a severe degradation of service. This paper describes a procedure to determine the permissible requirements on voltage quality-including the case of emergency set supply. On the basis of this analysis, a value of allowable input current distortion is proposed.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126952176","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}
{"title":"Quasi resonant AC/DC forward converter with sinusoidal input current","authors":"O. R. Schmidt","doi":"10.1109/INTLEC.1994.396612","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396612","url":null,"abstract":"Offline switching power supplies usually employ a rectifier bridge with a simple capacitor input filter to draw power from the AC line. The filter capacitor charges to nearly the peak AC line voltage, supporting an unregulated DC bus powering the switching power converter. Since the filter capacitor is charged only on the top of the peak line voltage, the capacitor has to be very large depending on hold up requirements. The line current waveform is (with a capacitor input filter) a nonsinusoidal, narrow pulse with a very high peak current. The input power factor is only 0.5-0.7 and the high harmonics of the current causes line noise. The RMS value of the input current may be twice the equivalent RMS sinusoidal waveform. The purpose of this paper is to present a cost effective AC/DC power converter where both functions are performed with a single switching transistor, transformer and chokes with output power up to 100 W.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116800550","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}
{"title":"Valve-regulated lead/acid batteries for modular installation","authors":"G. May","doi":"10.1109/INTLEC.1994.396668","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396668","url":null,"abstract":"Valve-regulated lead/acid (VRLA) batteries are particularly suitable for the modular installation of power supplies to support modern telecommunications equipment. These provide the high reliability demanded by digital loop carrier systems through the use of constructional features designed to meet service conditions over the full lifetime of the battery. Higher levels of packaged energy have been obtained and battery designs have been optimised for extended life in floating service. VRLA batteries are available in various types that are specially adapted to particular installations and duty cycles. The use of thinner plates will provide good performance at higher discharge rates as well as being able to provide power for longer discharges, but places additional demands on the design to achieve the durability required. Packaging requirements need to be considered for ease of installation and for some systems need to be ruggedised for easy handling. In this paper, the ways in which these conflicting requirements can be met by careful attention to all aspects of design are discussed and operational experience with various types of VRLA battery is reviewed.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116849932","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}
{"title":"High frequency alternating current power distribution","authors":"J. Drobnik","doi":"10.1109/INTLEC.1994.396620","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396620","url":null,"abstract":"The paper introduces high frequency alternating current (HFAC) power distribution as a new option in powering the equipment in telecommunications applications. A detailed comparison with powering schemes presently used in the telecommunication industry is part of the paper. The comparison is oriented towards the parameters of regulation, efficiency, input voltage range, output/input ripple, power density and EMI.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115230424","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}
{"title":"Resonant rectifier for high frequency switching converter","authors":"E. Sakai, K. Harada","doi":"10.1109/INTLEC.1994.396665","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396665","url":null,"abstract":"A rectifying unit to increase the switching frequency of a power converter is presented. The rectified current in the secondary of the power converter is commuted with this unit by a resonant technique and the commutation period can be reduced remarkably. As a result, the switching frequency can be raised significantly. Analysis and experimental confirmation are also presented.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128194965","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}
{"title":"Battery model for overcurrent protection simulation of DC distribution systems","authors":"T. Robbins, J. Hawkins","doi":"10.1109/INTLEC.1994.396617","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396617","url":null,"abstract":"This paper describes an electrical model of a battery that can accurately simulate characteristic battery behaviour during overcurrent instances. The battery model can be coupled with other distribution component models to simulate the protection performance in telecommunication DC power distribution systems.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122014687","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}
{"title":"Constant-power rectifiers for constant-power telecom loads","authors":"A. Kislovski, E. Olsson","doi":"10.1109/INTLEC.1994.396586","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396586","url":null,"abstract":"Constant-power loads that dominate in telecommunication plants feature a constant-power characteristic. Because of this they draw more current at a lower supply voltage than in normal operating conditions. If not over-sized, a power supply plant with constant-current rectifiers can latch after an interruption of the input line, and then the battery remains discharged. This paper shows that the use of rectifiers with constant-power output characteristic is an economic way for avoiding costly over-sizing or a risk of potential system breakdown.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"200 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122039081","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}
{"title":"Optimum engineered loop voltage drop for central office","authors":"L. Hinkel, C. Ashton, G. Margerum","doi":"10.1109/INTLEC.1994.396618","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396618","url":null,"abstract":"The loop voltage drop between the power distribution board and the battery distribution fuse board (BDFB) or power distribution (PD) frame is often not specified by the manufacturer of the served equipment. Common sense would seem to say that the engineer should buy smaller cables to decrease cable cost. This will result in a higher loop voltage drop than if larger cables were used. This paper shows, through economic analysis, that over a 20 year life study, the more expensive large cables (lower loop drop) actually cost less. A loop drop of approximately 1.0 V between the power distribution and PD Frame or BDFB is recommended.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126125284","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}
{"title":"Case studies of central office cable tray support failures","authors":"D. McMenamin","doi":"10.1109/INTLEC.1994.396652","DOIUrl":"https://doi.org/10.1109/INTLEC.1994.396652","url":null,"abstract":"Concrete anchor devices are an extremely important consideration when designing for network reliability. Most telephone central office cabling is supported on overhead cable racks or trays. Stored program control switching systems (SPCS) frames and modern transport equipment frames tend to be approximately 7 feet (178 cm) tall. Express cable trays to the power plant and main distributing frame (MDF) areas are usually supported by an auxiliary framing grid suspended from the ceiling slab. From a structural and earthquake protection viewpoint, both the equipment frames and the overhead structures are now separate and independent systems. This is a superior design plan, especially where building vibration or seismic activity is a consideration. Since metallic cabling, especially copper power cables, are quite heavy, all support elements must be capable of handling massive loads safely and reliably. Virtually all of the weight is borne by cast-in-place structures such as ceiling inserts, and embedded channel struts, or by anchors which are drilled and set by a variety of fastening systems. Two cable tray collapse failures in eastern Pennsylvania underscore the fact that some anchor designs are more prone to failure than others. This paper describes case studies of the two failures, and their root-cause investigations. Additionally, the paper discusses the results of dynamic pull-out tests, performed both in the laboratory and the field, on several traditional and newer style anchor designs, exploring their merits and drawbacks.<<ETX>>","PeriodicalId":123164,"journal":{"name":"Proceedings of Intelec 94","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128461452","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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