The Study of Possibility to Use the Current Transformer for Power Conversion

The current transformer is largely used in power system as instrument transformer which made possible the measurement of big intensity current (hundreds or thousands of Amps) by reducing to accessible values for usual instruments (1 - 5 amperes). Nominal current ratio and accuracy class characterizes it. Current transformer can supply measurement instruments connected to secondary winding, nominal power being in the range 10 - 102 VA. Exceeding of nominal power has as result exceeding of operating errors allowed by accuracy class. Use of current transformer for power transfer between primary and secondary windings, not as measurement instrument represents the main aim of the paper. Its design in that purpose will be made beginning from technique and economic reasons (nominal power, material consumption, power looses, efficiency etc.). It takes in consideration that secondary power has to be a constant voltage independent of primary current value for a large range of its variation (20... 120% from nominal current). There are presented also the experimental results made on current transformers used in power system or in laboratory, with magnetic core made by laminated silica steel or permalloy. There are verified practically dimensioning relations obtained for current transformer used as power converter and power transfer.