New precise comparison methods of testing watthour meters

Describes two methods which utilize only integral revolutions, counted over a continuous run. The first method-method of differences-permits the test to be limited (with moderate stabilization) to a single revolution, with mean precision ±0.02 percent. The second method-method of coincidences-measures accurately the relative error from a number of revolutions, dispensing with a stabilizer. No specially equipped reference meter need be used. A large number of meters can be tested within a short time interval by a single operator without special training. These methods, primarily developed for watthour meters, are suitable for other rotating instruments as well.