ABB 650 series Applications Manual page 307

1MRK 511 423-UEN A
Bay control REC650 2.2 IEC
Application manual
voltage inputs to the merging unit and the inaccuracy added by the merging unit
must be coordinated with the requirement for actual type of protection function.
Factors influencing the accuracy of the sampled values from the merging unit are
for example anti aliasing filters, frequency range, step response, truncating, A/D
conversion inaccuracy, time tagging accuracy etc.
In principle the accuracy of the current and voltage transformers, together with the
merging unit, shall have the same quality as direct input of currents and voltages.
Section 16
Requirements
301