ABB REL650 Applications Manual page 166

Section 6
Impedance protection
160
=
I 5 A
s
EQUATION1734 V1 EN
(
= +
Z 10.71 j 75.6
L 1
EQUATION1328 V1 EN
(
= +
Z 1.15 j 43.5
SA 1
EQUATION1329 V1 EN
(
= +
Z 5.3 j 35.7
SB 1
EQUATION1330 V1 EN
=
S 1000 MVA
max
EQUATION1331 V1 EN
( )
j
=
cos 0.95
max
EQUATION1332 V1 EN
j
= °
25
max
EQUATION1333 V1 EN
=
f 2.5 Hz
si
EQUATION1334 V1 EN
=
f 7.0 Hz
sc
EQUATION1335 V1 EN
The impedance transformation factor, which transforms the primary impedances to the
corresponding secondary values is calculated according to equation 74. Consider a fact
that all settings are performed in primary values. The impedance transformation factor is
presented for orientation and testing purposes only.
I
V 1200 0.115
= p × =
KIMP
s
I V 5
s p
EQUATION1735 V1 EN
The minimum load impedance at minimum expected system voltage is equal to
equation 75.
Rated secondary current of current protection transformers used
Line positive sequence impedance
)
W
Positive sequence source impedance behind A bus
)
W
Positive sequence source impedance behind B bus
)
W
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
× =
0.069
400
1MRK 506 334-UUS A
)
min
(Equation 74)
Application manual