Experimental Applications of Hall-Effect Wattmeters at 50 Hz

Since Hall effect is the result of multiplying together a magnetic and an electric field, taking into account any phase difference between them, a wattmeter employing a semiconductor device of this kind is a logical development. The paper describes three experimental applications in the United Kingdom, including single- and three-phase instruments metering the power input to 132 kV grid lines and also to 240 volt ac cables, with a record of their performance under practical operating conditions on Central Electricity Generating Board installations. Experience showed that using indium arsenide as the semiconductor element, temperature errors were reduced to an insignificant level and an overall accuracy of about ±2 percent was readily obtainable. It is claimed that this type of instrument applicable to high-voltage lines without the need for special current and voltage transformers is much cheaper than the conventional dynamometer equipment for the same purpose and quite as reliable.