ABB RELION 670 SERIES Applications Manual page 467

1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual
The warning angle (StartAngle) should be chosen not to cross into normal operating area.
The maximum line power is assumed to be 2000 MVA. This corresponds to apparent
impedance:
2 2
U 400
= = =
Z 80 ohm
S 2000
EQUATION1967 V1 EN
Simplified, the example can be shown as a triangle, see figure 237.
IEC07000016 V1 EN
Figure 237: Simplified figure to derive StartAngle
ZB
³
angleStart arctan + arctan
Zload
EQUATION1968 V2 EN
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.
X
ZA
Zload
ZB
ZA 32 52
=
arctan + arctan
Zload 80 80
Impedance protection
en07000016.vsd
»
0 0
= 21.8 + 33.0 55
Section 8
(Equation 432)
R
(Equation 433)
461