IEC 60524 Ed. 1.0 b:1975

Applicable to d.c. resistive volt ratio boxes with fixed ratios having a ratio input voltage up to 1.5 kV and a class index of 0.1 or better, as well as to all equipment which is built-in or supplied by the manufacturer (or responsible supplier) as an essential part of the volt ratio box. Classification system. Permissible errors for each accuracy class. Conditions for determination of errors. Markings. Information supplied by the manufacturer.