ABB RELION RET670 - Page 457

400
r
V kV=
EQUATION1728 V1 EN-US
Rated system voltage
min
380V kV=
EQUATION1729 V1 EN-US
Minimum expected system voltage under critical system
conditions
60
n
f Hz=
EQUATION1730 V1 EN-US
Rated system frequency
400
3
p
V kV=
EQUATION1731 V1 EN-US
Rated primary voltage of voltage protection transformers used
0.115
3
s
V kV=
EQUATION1732 V1 EN-US
Rated secondary voltage of voltage instrument transformers
used
1200
p
I A=
EQUATION1326 V1 EN-US
Rated primary current of current protection transformers used
5
s
I A=
EQUATION1734 V1 EN-US
Rated secondary current of current protection transformers used
( )
1
10.71 75.6
L
Z j= + W
EQUATION1328 V1 EN-US
Line positive sequence impedance
( )
1
1.15 43.5
SA
Z j= + W
EQUATION1329 V1 EN-US
Positive sequence source impedance behind A bus
( )
1
5.3 35.7
SB
Z j= + W
EQUATION1330 V1 EN-US
Positive sequence source impedance behind B bus
max
1000S MVA=
EQUATION1331 V1 EN-US
Maximum expected load in direction from A to B (with minimum
system operating voltage V
min
)
( )
max
cos 0.95
j =
EQUATION1332 V1 EN-US
Power factor at maximum line loading
max
25
j = °
EQUATION1333 V1 EN-US
Maximum expected load angle
2.5
si
f Hz=
EQUATION1334 V1 EN-US
Maximum possible initial frequency of power oscillation
7.0
sc
f Hz=
EQUATION1335 V1 EN-US
Maximum possible consecutive frequency of power oscillation
The impedance transformation factor, which transforms the primary impedances to the
corresponding secondary values is calculated according to equation
370. Consider a
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 451
Application manual