Application Guide - NP900 Series
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Figure 3.1.1.1-3 Phase current transformer scalings to CT nominal.
After the settings are input to the IED, scaling factors are also calculated and displayed for
the user. Scaling factor P/S tells the CT primary to secondary ratio, CT scaling factor to
NOM tells the scaling factor to nominal current (in this case it should be 1 since the
selected nominal current is the phase CT nominal). Per unit scaling factors to primary and
secondary values are also shown. In this case the scaling factors are directly the set
primary and secondary currents of the set CT.
If the settings would be wanted to be scaled to load nominal then the selection “Scale
meas to In” would be set to “Object In p.u.”
Figure 3.1.1.1-4 Phase current transformer scalings to protected object nominal current.
When measurement scaling is made to the protected object nominal current, the object
nominal current needs also to be set into the “Nominal current In” input. The differences in
