ABB RELION RET670 - Page 485

2
20
0.15 0.3
200
T
ZC jX j j ohm= = × =
EQUATION1974 V1 EN-US (Equation 408)
This corresponds to:
0.3
0.15 0.15 90
2.0
j
ZC j pu pu= = = Ð
o
EQUATION1975 V2 EN-US (Equation 409)
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 MV
A. This corresponds to
apparent impedance:
2 2
20
2
200
U
Z ohm
S
= = =
EQUATION1976 V1 EN-US (Equation 410)
Simplified, the example can be shown as a triangle, see figure 242.
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 479
Application manual