17.220.20 Measurement. Including measuring instruments, instrument transformers / Измерения электрических и магнитных величин. Включая измерительные приборы, измерительные трансформаторы
Описание
Classification. Class index system. Permissible errors for each class. Conditions for testing. Conditions for use. Methods of testing. Markings. Information to be supplied by the manufacturer.