ABB Relion 670 Series Applications Manual page 151

1MRK 511 358-UUS A
ANSI05000149 V1 EN-US
Figure 66: Connection of polarizing voltage from an open (ANSI-broken) delta
The different steps can be described as follows.
Step 1
This step has directional instantaneous function. The requirement is that overreaching of the
protected line is not allowed.
3I
0
67
67N
N
ANSI05000150 V2 EN-US
Figure 67: Step 1, first calculation
The residual current out on the line is calculated at a fault on the remote busbar (one- or two-
phase-to-ground fault). To assure selectivity it is required that step 1 shall not give a trip at this
fault. The requirement can be formulated according to equation 39.
³
I 1.2 3I (remote busbar)
step1
EQUATION1199 V3 EN-US
Application manual
×
0
67N
xx05000149_ansi.vsd
One- or two-phase ground-fault
ANSI05000150_2_en.vsd
Section 7
Current protection
M15282-123 v5
(Equation 39)
145