A.4 Current Transformer Requirements
541
7UT613/63x Manual
C53000-G1176-C160-2
Mismatching factor for 7UT613/63x, (limited resolution of the measurement)
Caution
: If earth fault differential protection is used, the requirement for the phase
current transformer of the REF side is as follows:
1
/
4
≤ F
Adap
≤ 4, (for the starpoint trans-
former remains
1
/
8
≤ F
Adap
≤ 8)
Figure A-30 CT verification for Devices 7UT613/63x
The CB layout within the power station unit is not specified.
where:
I
nO
= rated current of the protected object
(in relation to the parameterised rated current)
U
nO
= parameterised rated current of the protected object
I
Nrelay
= nominal device current
S
Nmax
= maximum (rated) power of the protected object
(for transformers: side with the largest (rated) load)
x”
d
= sub-transient direct-axis reactance of the generator in p.u.
U
k
= transformer short-circuit voltage HV - LV in %
R
relay
= assumed with 0.1 Ω, (the consumption of the above devices is below
0.1 VA)
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