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A simple and reliable PWM inverter to generate sinusoidal wave of constant voltage and variable frequency is presented. In the control circuit of this inverter, amorphous cores are used to produce PWM wave. These cores have three kinds of windings, that is, the common windings, the bias winding and the output windings. The bias winding gives each core a different amount of ac mmf to decide the order...
A research task was undertaken to evaluate the behavior of Ni Cad batteries under extreme temperature conditions. Identical tests were repeatedly performed in order to record the spread of terminal voltages and discharge capacity during (a) initial conditions, (b) after several charge/discharge cycles, and (c) under different temperature conditions. The test proved that significant degradation of...
The stationary lead acid battery is the dominating power reserve for telecommunications by reason of their high reliability which could be demonstrated in the past. Lead acid batteries can easily be recharged, methods for the conservation of the charge are even very simple. The required capacity and number of cells in correspondence to the specified time can easily be calculated. The following requirements...
A thermoelectric generator has been developed especially for the low power consumption radio equipment now being used to provide communication systems in developing areas. The new generator uses the same thermoelectric converter as used in Global's propane fueled Model 5120 which has proven high reliability and long life as established from seven years of field service throughout the world. However...
Lead-acid storage batteries are a vital part of any UPS installation. They supply the emergency power to the load in the event commercial power is interrupted or lost. Today's UPS batteries are specifically designed for their intended applications and differ significantly from those used in communication and switchgear service. Design considerations include plate thickness, separator and retainer...
The paper covers the basic factors which were taken into account when considering the installation of a Total Energy System in a major communications centre. It also describes the main components of the plant which is currently being commissioned ready for service. Tentative conclusions are given suggesting some limitations to the more widespread use of Total Energy Systems in telecommunications buildings.
The goal of this development was a stationary, standby, diesel engine alternator set in the 20 to 30kW capacity range that can be applied in telephone offices without the need for a dedicated engine room. It was further desired to minimize the effort of application engineering, installation and building modification for this set. The result of the development is an automatic engine alternator set...
A large capacity, float charged stationary lead acid cell designed to provide maximum electrical performance per square foot of floor space for a given height, superior sealing, minimum maintenance and optimum safety that meets the battery energy requirements for the next decade. Unique design features include a transparent jar that is self-extinguishing, a permanent thermal fusion jar-cover seal,...
Throughout the World, the requirements for automonous power supplies for telecommunication purposes are many and varied. This paper outlines the criteria to be considered when selecting power plants and identifies two major fields of application. Modular design of Plant and its installation in environmentally hostile conditions is considered and the affect of climate on power systems indicated. Design...
"Impulse Strength" is a relatively new parameter, having been defined officially as "the area under the amplitude-time relation for the impulse". In power systems, impulse strength is measured in volt-seconds, and it can be a critical factor in determining the "worst-case" performance of power-supply regulators, "line conditioners," or so-called "uninterruptible"...
This paper considers the reliability of several ring generator systems. The mean-time-between-failure (MTBF) is developed for a generalized system. This equation is applied to three specific cases.
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.
The evolution of electronic components in the computer field, especially increasing density and continuous reduction of the cost of processing and memorization integrated circuits, affects directly the design and development of equipments. The highest concentration of functions involves an increase in the specific power to be dissipated. This has to be taken into account when selecting the type of...
General Electric Company has developed the D67D (a high speed darlington) power transistor rated at 400 Volts (sustaining) and collector currents of 100 Amps continuous (160 Amps peak). The devices are monolithic and utilize a new power package which is available in the isolated (R??JC = .4??C/W max.) and non-isolated (R??JC = .25??C/W max.) collector configurations. Some typical applications for...
The specification for large UPS systems is becoming more standard, and this presentation is an attempt to highlight some of the less obvious points. The subjects chosen for discussion are input requirements of voltage, isolation and harmonics, together with considerations of the battery and the output filter. Areas for potential savings in energy and cost are investigated.
Designers involved in the ac power side of telecommunications equipment have been justifiably concerned with surge protection because field experience is rich in case histories of failures attributable to transient overvoltages. Insufficient knowledge of the exact nature of these overvoltages, however, has made their task difficult in the past. After several years of data collection by a number of...
A new British Post Office standard power plant has been designed to operate from a single-phase a.c. mains or standby generator input, and to provide secure d.c. power to 50 V telecommunications equipment. The plant features standby rectifier capacity, battery standby with a choice of duration, and a regulated output during battery discharge without the need for end-cell switching. A range of standard...
Two-core Wroblewski ferroresonant transformers up to 25 kVA have been built for 1-phase, and up to 75 kVA for 3-phase, 60-Hz operation. These transformers are used for the isolation, regulation, and transient suppression of line voltage for computers and other data-processing equipment. The transformers have also been used for general service in overseas 50-Hz poorly regulated electric-supply systems...
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