ABB RET670 Commissioning Manual page 125

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