Improvements in meter testing equipment

As the subject of meter testing is highly specialized, the paper first classifies and reviews the various methods of measuring the errors of a.c. kilowatt-hour meters. A description is then given of new equipment for rapid and precise testing in which decade counter tubes, controlled by a rotary sub-standard, are used to indicate the error. The substandard runs at the same speed on both unity and 0.5 power factor. Starting and stopping of the counter is effected with high precision without any mechanical movement. This is accomplished by optical and electronic means involving clip-on mirrors which are attached to the meter spindles by special tools. Push-button load selection, error tables and meter connecting plugs are employed. The results obtained and costs involved are given. A new device for preliminary setting of the quadrature and low-load adjustments is described; also a new dial-testing machine. Starting load-tests, creep tests and warming facilities are briefly discussed. Finally, the application of the electronic test method to the calibration of rotary substandards is mentioned.