ABB REG670 - Page 280

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 (Equation 166)
Simplified, the example can be shown as a triangle, see figure 142.
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN
Figure 142: 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
(Equation 167)
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°.
Section 8 1MRK 502 071-UEN -
Impedance protection
274 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual