ABB RET670 - Page 125

Table 20: Test points for phase-to-ground loop CG (Ohm/loop)
Test point Reach Value Comments
1 X [X1+XN] XN=(X
0
-X
1
)/3
R 0
2 X 0
R RLdFwd When RLdFWd < RFltFwPG
R RFltFwPG When RLdFwdPG > RFltFwPG
3 X 0.85·[X1+XN] R≈0.491·(X1+XN)+RFltFwdPG
R
4 X
0.85·[X1+XN]
Can be limited by RFltFwPG
R -0.85·[X1+XN]·
tan (AngNegRes-90°)
5 X RFltFwdPG·tan (LdAngle) Only when RLdFwd < RFltFwPG
R RFltFwdPG
6 X -0,5·RLdFwd·tan (ArgDir)
R 0,5·RLdFwd
Table 20 is used together with figure 25.
X1
R
X
85%
1
3
5
2
6
4
50% RLdFwd
ArgNegRes
0.5·RFltFwdPP
LdAngle
ANSI09000735-1-en.vsd
ArgDir
60°
)/( phaseW
)/( phaseW
7
ANSI09000735 V1 EN
Figure 26: Operating characteristic for phase selection function, forward direction
phase-to-phase faults
1MRK 504 165-UUS - Section 11
Testing functionality by secondary injection
Transformer protection RET670 2.2 ANSI 119
Commissioning manual