ABB REG670 - Page 191

~
HV Substation
ZMH PDIS
21 Z<
Y
Y
@
Generator CB
Auxiliary
Transformer
Step-up
Transformer
Excitation
Transformer
HV CB
F
i
e
l
d
C
B
CT: 4000/5
VT: 13,5kV/110V
70MVA
13,2kV
3062A
65MVA
123/13kV
x
t
=10%
REG670
IEC10000102 V1 EN
Figure 78: Application example for generator under-impedance function
The first under-impedance protection zone shall cover 100% of the step-up
transformer impedance with a time delay of 1.0s.
Calculate the step-up transformer impedance, in primary ohms, from the 13kV side as
follows:
1MRK 502 071-UEN - Section 8
Impedance protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 185
Application manual