Experimental Study on Voltage-Current Sensor embedded in Insulator

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The precise estimation of the electric power at the consumer end-side is eagerly demanded for the maintenance, control and the stable voltage regulation by electric power companies. There are several approaches to the observation of the power factor based on the practical waveform of both the voltage and the current. However, conventionally each sensor has been installed on power distribution lines independently. The measurement systems will be large and complicated to result in no maintenance free systems.To carry out the waveform observation for power factor, we have devised and proposed an insulator built-in type of voltage-current sensor. According to our previous investigations on the sensor, it was found out theoretically that a serious phase shift in the measured waveforms of the voltage and the current might occur owing to the electromagnetic interference of each phase.In this project, we have investigated the cause of phase shift in the voltage and current sensors through the finite element analyses on the single phase power distribution system, the horizontal and vertical three-phase power distribution systems. To compensate the phase shift in the current sensor, we have introduced the new current sensor coils, that are connected with opposite polarity to each other so that the sensor installed on each phase distribution line will measure only the flux linkage across its phase line and cancel the flux linkage due to other phase currents.Finally, based on the theoretical design, the prototype of the voltage-current sensor embedded in an insulator with above two coils has been fabricated in the insulator company and it has been found out experimentally that the effect of compensation on the phase shift in the current sensor could be obtainable in the simulated three-phase power distribution system.