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A Call Progress System generating telephone calling tones and ringing power with a high degree of flexibility is described. It has a multi-microcomputer architecture and is personalized for a particular application by use of a ROM.
Multi-output dc-to-dc converters controlled by magnetic amplifiers are presented. In these power converters, the magnetic amplifiers with frequencies of 80 to 400kHz are used instead of the conventional switching transistors. The magnetic amplifier and an additional saturable core suppress the surge occurrence, and consequently these power converters can operate with the relatively low power dissipation...
A new PWM controller with simple structure is presented. This controller consists of a modified transistor-core multivibrator having a single saturable core and is capable of changing the oscillation frequency with ease by a low control voltage. Accordingly, if this controller is applied to a small DC power supply or a feedback element of the switching regulator, a considerable reduction of the number...
This paper is mainly concerned with the latest strong technological developments on high-power fast-response switching dc-dc converters controlled by time-sharing/sequencial high-frequency thyristor resonant chopper comprising energy-storage and-transfer reactor assemblies, which can operate over an ultrasonic chopping frequency region in the extent of 20 KHz or more than 20 KHz or so. The possible...
A ringing choke converter using a single core saturable reactor in the control circuit is described. Besides the few components, simplicity and small size usually found in self-oscillating converters, this converter features a saturable reactor protective functions for overcurrent through the main transistor switch and for magnetic saturation of the power transformer, and good isolation of output...
The design of a reliable DC - DC converter requires knowledge of the stress levels on critical components under worst case conditions. Although specifications define the steady state and transient limits for influence quantities, the performance of converter circuits during normal transitions between operating states can result in high stress conditions. The variability of component parameters adds...
Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle...
Developments in the telecommunication equipment require new centralized power plant policy. The paper describes the new type of power plant chosen by SIP, Italian Telephone Company, to face the telecomuunication equipment present and future requirements. A description of the plant is given together with the results of the first years of operation.
The paper describes some devices specially developed for the new type of centralized power plants for telecommunication equipment used by SIP, Italian Telephone Company. The remote rectifier's output power limitation device is of great usefulness in the power rating of the primary power plant, in particular of emergency generating sets. The selective supervising devices are an integral part of the...
Technical progresses in the field of power transistor permit now a direct switching of AC mains voltage. It is the main object of this paper to present a modular rectifying set, including two to five switching rectifiers. The main technical points concerning this type of telecommunication power plant will be discussed, thas is the electromagnetic compatibility between these materials and the surrounding...
The paper describes the hardware and software methods used to effectively test and diagnose DC to DC converters. The design requirements for the programmable sources and loads are described and the measurement schemes for ripple and alarm tests. The converter test set is presented as a part of a larger computer aided manufacturing sytem with two levels of hierarchy that follows the product from the...
Booster DC to DC converters operating with 20 kHz conversion frequency perform rapid regulation that make them very well suited to use as active filters for attenuation of low frequency noise. Booster converters with such filtering qualities are beeing used in a new series of 48 V DC power plants. The noise on the output is kept well below the limits that are specified in the CCITT-recommendations.
CIT-ALCATEL Series SPC 2700 is a twin tube coaxial cable telecommunications system that can support 2700 two-way vf channels or equivalent signals e.g. broadcast TV, up to 12 Mhz wide plus a digital bit stream up to 8448 kbit/S, over a range up to 2500 km (1500mi) between main stations. The repeaters are powered in a series loop with one remote power supply at each end of a power span. This paper...
In this paper an attempt is made to derive some major future trends for telecommunication power plants out of technological progress and some of the worldwide political processes. The main stress is laid on trends of some degree of universal applicability and thus detailed analysis of e.g. circuit solutions is avoided. General trends, system trends and trends for system components like rectifiers,...
Repeater stations in telecommunication networks are often located in unpopulated areas without a developed infrastructure or a public power supply. D.C. power must be supplied by electric power generating equipment at each station. In addition to the well established means of generation, pew methods are finding increasing application. Photovoltaic, wind energy and fuel cell systems will be described...
This paper discribes power converters used and in the research phase in NTT. Nowadays, almost all converters are semiconductor converters. Since they are efficient, small and reliable, they are used in many telecommunication systems. Recent progress in the telecommunication systems enhances the requirement for further converter development. Studies on converters have been continued to minimize size,...
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