ABB REL670 2.2 IEC - Page 441

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 441)
Simplified, the example can be shown as a triangle, see figure 238.
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN-US
Figure 238: 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 442)
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°.
1MRK 506 369-UEN B Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 435
Application manual