The integration of current instrument transformers, with optic transmitting of information, into actual measuring systems

Abstract

The trends to improve the performances of the classic instrument transformers were oriented to introduce new materials, components and methods in the design, manufacturing and operation. The paper presents some technical solutions adopted to integrate a current instrument transformer into measuring system at medium voltage. The transformer uses a fiber optic link to send the measuring signal from the medium voltage point to the monitoring point. Also, the solutions for the limiting and protection of inputs of the transformer unit against accidental overvoltage are presented. On the monitoring side, the measuring signal is converted from voltage signal to current signal which flows through an ammeter or a current loop for remote control and telemetry. Also, the analog to digital conversion is possible to send the result of measurement at the master monitoring system. Finally, the waveforms, recorded during the performed tests, are presented.