This part of IEC 60076 illustrates the procedures that should be applied to evaluate the uncertainty affecting the measurements of no-load and load losses during the routine tests on power transformers. This document centers on measuring systems utilizing digital instruments, although the procedures can be adapted to evaluation of systems with analogue instruments where further uncertainty sources have to be taken into account. This document describes how to determine measurement uncertainty. Information vis-à-vis judgment and traceability are given in Clauses 10.1 and 10.2 of IEC 60076-8:1997