0.3
0.15
0.15 90
2.0
j
ZC
j
pu
pu
=
=
=
Ð
o
EQUATION1975 V2 EN-US
(Equation 464)
Set ZC to 0.15 and
AnglePhi to 90°.
The warning angle (
StartAngle) should be chosen not to cross into normal operating area. The
maximum line power is assumed to be 200 MVA. This corresponds to apparent impedance:
2
2
20
2
200
U
Z
ohm
S
=
=
=
EQUATION1976 V1 EN-US
(Equation 465)
Simplified, the example can be shown as a triangle, see figure
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN-US
Figure 254: Simplified figure to derive StartAngle
0
0
arctan
arctan
arctan
+ arctan
= 7.1 + 5.4
0.25
0.19
13
2
2
³
=
»
ZB
ZA
angleStart
+
Zload
Zload
EQUATION1977 V2 EN-US
(Equation 466)
In case of minor damped oscillations at normal operation we do not want the protection to
start. Therefore we set the start angle with large margin.
Set
StartAngle to 110°.
For the
TripAngle it is recommended to set this parameter to 90° to assure limited stress for
the circuit breaker.
Section 7
1MRK 505 343-UEN B
Impedance protection
388
Application manual
Summary of Contents for Relion 670 series
Page 1: ...RELION 670 SERIES Line differential protection RED670 Version 2 1 IEC Application manual...
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