ABB Relion 620 Series - Page 605

Table 530: Protected generator values
Quantity Value
S
n
8 MVA
U
n
6 kV
I
n
770 A
I
kmax
4620 A (6 × I
n
) out-of-zone fault
I
kmaxin
9.24 kA (12 × I
n
) in-zone fault
Table 531: Assumed CT data
Quantity Value
CT 1000/1 A
R
in
15.3 Ω
U
kn
323 V
I
e
35 mA (at U
kn
)
Figure 318: Example calculation for high-impedance differential protection (only one
phase is presented in detail)
The length of the secondary circuit loop is 200 m and the area of the cross-section
is 2.5 mm
2
. Resistance at 75°C is 0.00865 Ω/m.
1MRS757644 H
Protection functions
620 series
Technical Manual
605