ANSI05000152_2_en.vsd
One phase-to-ground fault
67N
ANSI05000152 V2 EN-US
Figure 73: Step 1, third calculation
In this case the residual current out on the line can be larger than in the case of ground
fault on the remote busbar.
EQUATION1201 V3 EN-US (Equation 41)
The current setting for step 1 is chosen as the largest of the above calculated residual
currents, measured by the protection.
Step 2
M15282-144 v7
This step has directional function and a short time delay
, often about 0.4 s. Step 2 shall
securely detect all
ground faults on the line, not detected by step 1.
67N
One- or two-phase ground-fault
50/51N
ANSI05000154 V2 EN-US
Figure 74: Step 2, check of reach calculation
1MRK 511 401-UUS A Section 8
Current protection
Bay control REC670 2.2 ANSI 181
Application manual
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