Abstract :
The paper deals mainly with developments in meter-testing methods which use a watt-hour meter as the standard of reference. A brief survey is included of methods, developed during the last forty years, in which some form of stroboscope has been included, and it is shown that such methods cannot be used for light-load testing owing to the fact that most meters are subject to cyclic variations. Particulars are given of recently devised schemes which incorporate a stroboscope for the higher loads and some other form of testing for the light loads. A description is then given of a new type of meter-testing unit which uses revolving optical compensators to view the disc of a meter under test, in order to compare its speed with that of a substandard meter. An image of the disc marks is obtained which is very similar to a stroboscopic image, but with theimportant difference that cyclic variations do not prevent its use for light-load testing. The new unit can therefore be used for testing meters at all loads from 1/20th to full load, and, as facilities are provided for testing meters having different constants, it is particularly suitable for use in supply authorities´ test rooms dealing with different makes of meters, so that its application in this respect is considered in some detail.
