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This paper describes the application of the theory of symmetrical components to three-phase rectifiers. The basics of the theory are given and the concepts of the theory are applied to first find a circuit that acts like an artificial neutral point (ANP) and secondly, to find a design criterion for the ANP circuit.
This paper gives the basic review of the technology development of rectifiers for central power plants in telecommunications centres. The following rectifier technologies are described - transductor-controlled rectifiers with polycrystalline and monocrystalline valves; - thyristor-controlled rectifiers; - ferroresonant stabilizers and controlled ferroresonant devices; - switched mode direct-off-line...
Low-pass passive filters used in power converters attenuate low frequency ripple in a very inefficient way. The purpose of this paper is to show how small power active filters can effectively suppress low frequency ripple levels in large power systems. Switchmode power converters with high switching frequency and high gain voltage feedback control have been used as active filters. Three different...
This paper provides a continuation of previously presented (1) availability analysis of power and cooling subsystems in an electronic switching centre. The following items are treated in particular. Failure mechanisms of power and cooling equipment are interconnected, both subsystems including common elements such as AC power supply. Availability calculations are carried out considering this interconnection...
Another paper (1) presented at this INTELEC Conference describes a hybrid power plant for remote sites, ERICSSON SUNWIND, consisting of solar, wind and minidiesel power sources. This power plant includes a microprocessor-based control system for output power optimization of the wind turbine; - this deserves a separate description. The wind turbine used in ERICSSON SUNWIND is a combined Darrieus-Savonius...
The reliability of a modern electronic switching centre depends to a high degree upon the reliability of the auxiliary systems such as power supply and cooling. Reliability studies of power supply have been presented at previous sessions of INTELEC. This paper presents an integrated approach covering the determination of the availability for power supply and cooling equipments as well as their impact...
Primary switched power supplies operating at supersonic conversion frequencies (20-50 kHz) are usually based on duty cycle control. This paper presents another possible technique - ferroresonant control. The difficulties connected with the application of the ferroresonant principle at high frequencies can be eliminated by using the controlled ferroresonant technique. The paper covers the principle...
This paper describes the development work carried out in the Power Supply Department at L M Ericsson during recent years on the design of dc power plants. Beside the standard system solution applied in different markets for the supply of all kinds of telecommunication equipment, some special designs and system modifications will be mentioned.
This paper describes a new generation of power equipment for 48 V dc, recently issued by the Power Supply Department of L M Ericsson. Major application area will be the powering of new electronic switching systems AXE and AXB. The system solution with booster converters was applied in the equipment. The new feature represent the booster converters operating at 20 kHz. The equipment is intended to...
This paper describes the development work carried out in the Power Supply Department at L M Ericsson during recent years on the design of dc power plants. Beside the standard system solution applied in different markets for the supply of all kinds of telecommunication equipment, some special designs and system modifications will be mentioned.
This paper describes a new generation of power equipment for 48 V dc, recently issued by the Power Supply Department of L M Ericsson. Major application area will be the powering of new electronic switching systems AXE and AXB. The system solution with booster converters was applied in the equipment. The new feature represent the booster converters operating at 20 kHz. The equipment is intended to...
An uninterruptible ac supply system consisting of two power sources (static inverter and ac line) and a thyristor switch is presented. The thyristor switch is operated in such a way that the equalization current flow between the sources is prevented. Consequently continuous parallel operation of the sources may be applied. Faults in one of the sources do not affect the voltage supplied to the load...
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