Regulation always stops when earth fault occurs because the same zero sequence volt-
age would measured across the coil's whole adjustment range making regulation
impossible.
The earth fault generates two types messages:
– The immediate earth fault message
This message displayed soon the earth fault has been identified.
– The delayed earth fault message.3.2. The earth fault must also occur
during the whole delay time. This value relates the nominal value the coil's nominal voltage.
11.
This message displayed after the set delay time.
Default setting: 30%
0 Uerd message delay:
Transient earth fault
An earth fault identified when the absolute value the zero sequence voltage Une is
higher than the threshold value set for Uerd.
Une
Transient earth fault
Message delay
T_V
T_EW
t
T_EW Transient earth fault time
T_V Uerd message delay
Figure 76: Time behaviour the earth fault
. The below figure displays the time behaviour
for the regulator. also not certain whether older coils can moved when earth fault oc-
curs because the drive unit not always equipped overcome the high magnetic forces.1 Earth fault
0 Uerd threshold
If the set threshold exceeded, the coil movements and the current injection (if used) are
suppressed.Page 105
Detailed description REG-DP/ REG-DPA parameters
Four parameters determine the regulator's behaviour when earth fault occurs
