ABB Relion 670 Series Applications Manual page 112

Section 7
Impedance protection
=
V 400
r
EQUATION1728 V1 EN-US
=
V
min
EQUATION1729 V1 EN-US
=
f
n
EQUATION1730 V1 EN-US
400
=
V
p
EQUATION1731 V1 EN-US
0.115
=
V
s
EQUATION1732 V1 EN-US
=
I
p
EQUATION1326 V1 EN-US
=
I 5
s
EQUATION1734 V1 EN-US
=
Z
L 1
EQUATION1328 V1 EN-US
=
Z
SA 1
EQUATION1329 V1 EN-US
=
Z
SB 1
EQUATION1330 V1 EN-US
S
max
EQUATION1331 V1 EN-US
(
j
cos
EQUATION1332 V1 EN-US
j
max
EQUATION1333 V1 EN-US
=
f
si
EQUATION1334 V1 EN-US
=
f
sc
EQUATION1335 V1 EN-US
The minimum load impedance at minimum expected system voltage is equal to equation 16.
Z
L min
EQUATION1736-ANSI V1 EN-US
106
kV
380 kV
60 Hz
kV
3
kV
3
1200 A
A
( )
+ W
10.71 j 75.6
( )
+ W
1.15 j 43.5
( )
+ W
5.3 j 35.7
=
1000 MVA
)
=
0.95
max
= °
25
2.5 Hz
7.0 Hz
2 2
V 380
min
= = =
144.4
S 1000
max
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Rated system voltage
Minimum expected system voltage under critical system
conditions
Rated system frequency
Rated primary voltage of voltage (or potential) transformers
used
Rated secondary voltage of voltage (or potential)
transformers used
Rated primary current of current transformers used
Rated secondary current of current transformers used
Positive sequence line impedance
Positive sequence source impedance behind A bus
Positive sequence source impedance behind B bus
Maximum expected load in direction from A to B (with
minimum system operating voltage V
Power factor at maximum line loading
Maximum expected load angle
Maximum possible initial frequency of power oscillation
Maximum possible consecutive frequency of power
oscillation
W
1MRK 511 407-UUS Rev. J
)
min
(Equation 16)
Phasor measurement unit RES670
Application manual