ABB RELION RET670 Applications Manual page 485

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