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Programmable logic control (PLC) microprocessors are designed to take the place of hard-wired relay and contactor-control assemblies. Among the multiple advantages offereo are a wider scope of task adaptation and protective devices, rapid functional testing with less instrumentation in a small space: and greater reliability and endurance following therefrom. These merits can of course be put tc good...
This paper describes a DC power supply consisting of a number of parallel operating charging rectifier units operating on a common battery bank. This system is developed for and in cooperation with The Norwegian Telecommunications Administration. A control system takes care of the load sharing independant of the number of charging rectifier units in parallel. A monitoring system can take care of units...
Research and experience have shown that cell voltage plays a significant role for the service lifetime of constantly charged high-antimonic lead batteries. It is generally believed that this also occures for newer types low-antimonic lead batteries. Since a battery charger keeps the total voltage at a constant level there will excist deviations between the individual cells. As a consequence of this...
A photovoltaic (PV) system is an economical solution for power supply problems of telecommunication stations in rural areas. Photovoltaics is a new concept and consequently the standards and specifications have not yet been fully developed. This paper presents some aspects about specifying, sizing, and designing a PV-system. Also some experiences on carrying out a large telecommunication project with...
Since 1972 the Greenland Telecom Service has been operating a 1500 km microwave radiolink from Cape Farewell to the Diskobay area on the westcoast of Greenland. This link system incorporates 25 unmanned, rather inaccessible repeater stations on mountain sites at heights from 100 to 1500 meters above sea level. The supply of such stations with the necessary electric power has created many problems...
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...
The telecommunications industry is evolving toward a more distributed system architecture. Stored Program Controlled switching machines will interface with feature processors so new services can be integrated into the network. This is expected to reduce the financial outlays, and lead times previously expended to implement hardware dependent new features. Additionally, computerized Operational Support...
Field reliability data are described with references to 48V/60V 300A power plants, developed by ITALTEL according to specifications of SIP, Italian Telecommunication Operating Company. Each power plant consists of a power distribution system, 60A rectifiers and 25A buck-boost converters, redundant parallel operating with load sharing and selective cut-off of failed unit. The period under examination...
Point of view of safety authority which is responsible of the safe use of electricity in Finland, about the international safety requirements for telecommunication equipment.
As the most widely used means to know the charged condition of a lead-acid battery, the method to measure the specific gravity of the electrolyte is adopted. Here we report in this paper on an optical-type sensor taking advantage of the fact that the sulfuric acid electrolyte has a certain definite refractive index in accordance with its specific gravity and the device applying such a principle. Several...
Satety of telecommunication equipment and systems are going to become internationally standardized. Because of the far reaching interconnections via telecommunication networks, safety is a most important factor in designing and constructing telecommunication equipment and systems. In the past safety standardisation of telecommunication was a national task mostly adressed by the telecom administrations...
The number of telecom switching offices in the Swedish network is about 7000 and among those, roughly 90% have 2000 lines or less. When converting the telecom equipment from electromechanical to SPC technique, the number of minor switching exchange offices will increase. This paper describes two power supply systems introduced by the Swedish telecom administration as standards for minor telecom installations...
KOKUSAI DENSHIN DENWA CO., LTD. (KDD) will construct the transpacific optical fiber submarine cable system (TPC-3) between Japan, Guam and Hawaii in 1988, with AT&T. This system has a total system length of about 9000km. The power feed equipment (PFE), for long haul optical submarine cable system like as TPC-3, needs capability of feeding the large constant current, standing on the high voltage,...
A power-feeding system developed for digital signal-transmission systems on optical fibers is presented. It consists of 1 to 3 power-feeding units (400 mA, 700 V each), a power-feeding control unit, the power-feeding cable and the remotely-fed converters to supply the loads. The power-feeding control unit performs a route test before the power-feeding is switched on, locates route faults and monitors...
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.
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