The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
For around 20 years, the IEC static convertor standards committee has included a study group dealing with the formulation and development of IEC standards for UPS systems. In this connection, a corresponding European standardization project exists in CENELEC since 1988 with the aim of taking into account as quickly as possible, in the safety conditions for power supply devices in office equipment,...
This paper presents a newly-developed high-performance 3??CVCF power conversion conditioner incorporating a new Quasi-Resonant DC Link (QRDCL) single-phase inverter with PWM function and high-frequency AC transformer linked cycloconverter topology. The operating characteristics of a proposed QRDCLI are discussed on the basis of computer-aided simulating results. In order to achieve a significant improvement...
This article put forward the technical choices selected for the development of a single phase and three phase UPS range from 5 to 30 kVA. The authors present the topology selected in order to optimize the range, and some performances of these UPSs.
The majority of present day UPS systems is based on the traditional dual conversion topology. In this concept, all the energy for the critical loads is converted twice: first from AC power into some kind of intermediate energy that can be stored as kinetical or chemical energy, and than, in a second conversion, again into stabilised AC power for the loads. This concept is now widely used and appreciated,...
The backup battery of UPS has several kinds of physical failure modes, for example, that is caused by the loss of energy, the stress exposed from outside and the stress from inside. To find an entire failure rate, we consider this effect as a series phenomenon of each failure mode. On the assumption that backup battery of UPS has operation failure p.d.f of Erlang, we investigate the relation between...
To the traditional requirements on cooling systems for switching equipment, are now added, concurrently with rising energy prices and labour costs, requirements on energy- and space-efficiency and installation- and maintenance-friendliness. This paper describes a cooling system based on water, with compact units that can be placed in the same room as the equipment to be cooled by the system. The heat...
Today there are three main possibilities for further energy savings in the cooling of digital switching rooms of the Telekom, using the existing unit technology: - Change to constant temperature difference control The savings potential of this measure mainly depends on the existing partial load condition of the individual installation. The magnitude cannot be indicated in general, but as an average...
The paper discusses two alternative high Power Factor approaches to input current shaping in 3-phase rectifiers. The first approach gives higher value of Total Harmonic Distortion but is much simpler and thus cheaper, more efficient and more reliable. The second approach reduces the THD but is much more complicated and expensive. It is concluded that, from the user point of view, there is no need...
The introduction of a network management system is a process extended over a long period of time. All long term plans are based on forecasts. These forecasts in turn are based on experience of previous development. Because of rapid technological development in the field of network management together with increasing demands for cost effective operation of the telecommunications network, the need for...
The demands of the IEC 555 standards call for high power factor AC/DC converters to fulfill the harmonic components requirements. A conventional designed converter would include two power stages: one AC/DC converter for the power factor correction and one DC/DC converter including the main to output safety isolation. In this paper a single stage power converter including power factor correction and...
Over the past twenty years there have been significant alterations to large UPS systems and similar changes have taken place on DC power systems for telecommunications. Both have electronic circuits to condition the power and batteries to supply the energy in the event of mains failure. In the early days it was generally the policy to back up the whole, building when a UPS was employed. The incoming...
The German manufacturer union (VDMA) and the utility union (VDEW) have agreed on the paper "Richtlinie f??r den Anschlu?? von prim??r getakteten Schaltnetzteilen mit B6-Drehstromein-gang (Standard on the connection of switch-mode power supplies with B6-three-phase-input)", which are used in telephone centrals. This paper gives the relevant background information to calculate the required...
There is a continuing move in power provisioning for telecommunications to valve-regulated lead/acid (VRLA) batteries. Reductions in maintenance and an increasing need for distributed power have been key driving forces. The rapid extention of fibre optic networks is resulting in a wider distribution of power to a larger number of points in the system. This is creating a requirement for batteries with...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.