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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...
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...
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...
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...
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...
This paper compares the reliability of four uninterruptible power supply (UPS) configurations; single module, parallel redundant, static bypass, and static bypass redundant. Equations for calculating the MTBF's of these configurations are presented along with component reliability estimates. Effects of failure rates of associated circuitry are included. System MTBF's of 200,000 hours for redundant...
The success of the application of switched mode techniques to d.c. power supplies has naturally led to developments of these techniques for the generation of a.c. voltages. Recently attention has been given to the use of microprocessors to program the outputs of these function generators. A low frequency programmable function generator has particular application in the telephone industry, where there...
This paper describes a new approach to the realization of a power frequency converter. The system is designed to accept either a three phase or single phase input with an unregulated frequency and to produce a single phase output with a precise 60 hz frequency. The system uses only one high speed power transistor switch and two SCR's featuring zero crossover switching. With a three phase input, the...
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 use of standby generators as peak shaving devices pays dividends in several ways. The practice of using the generators as peak shavers reduces the demand rate, eliminates the need to "test" the generator periodically, utilizes the fuel in a time frame which prevents contamination and better utilizes the capital investment. This paper discusses the methodology used to accomplish this.
A total battery plant system consisting of rectifier/chargers and a voltage control and distribution bay is discussed. The rectifier/chargers each have built-in provisions for testing and adjusting their high and low voltage alarms and their high voltage shutdowns without removing them from service or affecting their outputs during the testing sequence. Likewise, the voltage control and distribution...
This paper deals with the specifications, characteristics, functions, and examples of applications of the Electronic Universal Load developed for use in the developement of power supply units, their testing and income inspection. The function of controlling load current by entering a BCD code permits, among other functions, automatic testing through connection to a computer. This paper gives a detailed...
The development of digital telecommunications switching equipment with its lower power per Erlang of traffic and its more constant power requirement at a time of increasing energy shortage has created the need to re-consider conventional cooling practices and to examine other less conventional methods. This paper describes current telephone exchange cooling practices, the environmental requirements...
This paper describes the methods adopted to reduce long term energy consumption by the British Post Office Telecommunications and their application to existing and new buildings.
This paper will describe a power system configuration that provides improved energy efficiency for telephone power plants. This is accomplished by supplying the plant load with a voltage lower than typically used. The approach will be explained using a standard configuration for a +24 volt (12 cells per string) battery plant. The following points will be emphasized: - Circuitry necessary to maintain...
A high efficiency and economical arrangement for providing power to computers with 400 Hz CPU requirements is introduced. The system utilizes a conventional 60 Hz static switching bypass type 60 Hz UPS connected to a common battery with a switching type redundant 400 Hz solid state UPS thus eliminating the double conversion losses and lower efficiency of an added rotary frequency converter. A method...
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