ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN-US
Figure 242:
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 411)
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.
If the centre of pole slip is within the generator block set
N1Limit
to 1 to get trip at first
pole slip.
If the centre of pole slip is within the network set
N2Limit
to 3 to get enable split of the
system before generator trip.
Section 8
1MRK 504 163-UUS A
Impedance protection
480
Transformer protection RET670 2.2 ANSI
Application manual
Summary of Contents for RELION RET670
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