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As a result of small computers becoming increasingly more powerful, there is a trend among computer users towards smaller systems. Nevertheless, large computer installations will still be needed for the foreseeable future. The reason is their increasing capacity and ability as well as the fact that it is very costly to close down an established large computer system such as one used for operations...
The discription of the various system shows that the problems of each individual requirement will decide in favour of one or other UPS system. Computer systems with a frequency tolerances of +/- 1 % will definitely demand the use of NO-BREAK sets with static converter controlled synchronous motor drive. Space requirements are compartitively modest, as no battery equipment is needed for energy storage...
Electronic power converters operating with a high-frequency link are receiving an increasing amount of attention. A forced interruption in current in the semiconductor switches will lead to excessive momentary values of the power compared to the conduction losses for the current conduction interval, which must be dissipated in these switching elements. The switching losses are the fundamental reason...
Conventional series-resonant converters suffer from wide variations in conversion frequency during constant voltage regulation, resulting in audible noise under light-load conditions. A new series-resonant converter has been developed in order to eliminate this problem. The converter uses a parallel resonant circuit with a resonant frequency of over 20 kHz installed in series with the load circuit...
This paper presents the softwares and hardwares for a new switched-mode DC-DC converter circuit which incorporates a single symmetrical PWM control-based voltage-fed series resonant high-frequency inverter as a sub-system for the internal power conversion and processing stage. In the first place, it refers to a novel circuit topology of the series resonant type high-frequency inverter linked DC-DC...
A novel constant-frequency, clamped-mode parallel-resonant converter is proposed and analyzed. Employing graphical state-plane techniques, five circuit operating modes together with their operating regions are defined, regions for natural and forced commutation are specified, and the dc control-to-output characteristics are derived. The predicted operating modes are experimentally verified using a...
This paper describes a new forward DC-DC converter that regulates the output voltage for a very wide range of input voltages. In a forward converter, the voltage across the transistor switch (Tr) is the sun of the input voltage and transformer clamp voltage, and the voltage across the rectifier diode (Dr) is proportional to the transformer clamp voltage. In a conventional converter, the transformer...
The paper is dealing with two commonly used topologies for pulse width modulated inverters. The first is based on a PWM converter that transforms the DC-input voltage into a high DC-output voltage, followed by a PWM bridge for waveshaping and inversion. The second uses a forward PWM-converter for transformation and waveshaping at the same time. It is followed by an inversion bridge to obtain a sine-wave...
A new 100A, 500V n-channel enhancement mode power MOSFET module is introduced in this paper. In the introduction an overview on the existing devices has been given. The nunerous merits of the new device are illustrated by means of various static and dynamic characteristics. The classic problem of intrinsic bipolar action, which leads to destruction of power MOSFET have been discussed. The new device...
In the paper the unified topological small-signal modelling method is extended to switching dc-dc converters in current-programmed mode. The method leads to the unified analytic expressions for parameters of the Y-type model and allows easy inclusion of the mutual inductances, damping networks and parasitic effects. As a result the method offers a simple to use modelling procedure especially efficient...
Because of the environmental requirements placed on traditional batteries and the noise emanating from the power equipment, power supply units have always been located separately from the telephony equipment they serve. New technology in power components and batteries has made it possible to install the power in the same room as the telephony equipment. This paper will deal with the gains obtained...
In the last decade, the Telephone Industry has dramatically changed the methods for providing communication transport from business and residential customers to the local serving telephone office. The standard pairs of wires used for subscriber loops have been rapidly replaced by the use of Subscriber Loop Carrier Systems (SLC?? Carrier), electrically combining groups of customers (i.e. 24) on only...
Brazil is a country with a large territorial extension which is divided into 26 states. Each state has its own telephone administration. Determined by the characteristics of each state, which vary from S??o Paulo with more than 12 million inhabitants in its capital to Amazonas with small villages in the Amazonian forest, there are significant differences between the administrative and operational...
After a general presentation of a new kind of supply systems for telecommunication exchange developped from the A.C. source to DC outputs ; we give an overview of one of its most important subset: the decentralized DC rack ; it will be another opportunity to emphasize concepts like : - short battery autonomy, - use of the redundancy on the exchange, - wide voltage range, - high efficiency, - modularity...
The development of electronic telecommunication systems and the offer of new services have pushed SIP (Italian Operating Telecommunication Company) to update the philosophy of its own power plants also taking into account the objectives of reducing installation, operation, maintenance and management costs. All the above requirements have rise to a new power plant for telecommunication systems realized...
The ever increasing complexity of electronic systems together with higher requirements on availability is continuously increasing the interest in redundant power supplies. This paper will describe the system design considerations for a Modular Multiple Output Redundant SMPS System.
In the telephone exchange system AXE, ring signal generation is distributed to the line interface magazines, each supplying ring signal to one Line and Switch Module (LSM) of 128 subscriber lines. This paper discusses the system aspects which led to this configuration and also some technical details of the internal design of the ring signal generators.
A local energy system including many solarcells and a single secondary battery is presented. These energy sources are connected to an ac bus line through inverters. The bus line supplies ac power to many loads. In this system, the output voltage of each solarcell is always kept constant by each interface in order to derive the maximum power from each solrarcell even when the ligtht strength from the...
The present work describes the main problems - and their corresponding solutions - in the implementation of photovoltaic energy systems for remote microwave repeaters. Initially, it was necessary to show the operational personnel the photovoltaic systems advantages of reliability and low maintenance requirements. The first goal was the installation of twenty "Photovoltaic Economizers Systems"...
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