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:
EQUATION1967 V1 EN-US (Equation 401)
Simplified, the example can be shown as a triangle, see figure 239.
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN-US
Figure 239: Simplified figure to derive StartAngle
0 0
32 52
arctan arctan arctan + arctan = 21.8 + 33.0 55
80 80
³ = »
ZB ZA
angleStart +
Zload Zload
EQUATION1968 V2 EN-US (Equation 402)
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 mar
gin.
Set StartAngle to 110°
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 475
Application manual
To Next Page
Loading...
