Design and Implementation of Thermal Converter for AC Volt Measurement

There are several designs and techniques for measuring the ac voltage. The ac-dc thermal transfer standards represent the common method for measuring the ac voltage accurately in terms of the dc voltage. The single junction thermal converter (SJTVC) is widely used as thermal transfer standard. It is to be noted that the SJTVC is mainly an electric resistor (heater) whose temperature is sensed by a standard thermocouple. This device has an input which is ac voltage and an output signal represented by the output voltage of the thermocouple. This thermal converter suffers from many drawbacks such as, it has low dc output voltage requiring accurate milli-voltmeter to measure it. This leads to high uncertainty and not very high accuracy of ac voltage measurement. These drawbacks are studied and treated in this thesis through fabricating of modified designs TVCs. The suggested solution depends on three different electrical connections of a number of new single junction vacuum thermocouples their heaters leads gathered in three groups; Series, Parallel and Series/Parallel arrangements. The modified TVCs are implemented entirely in National Institute for Standards (NIS), Egypt.