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8.3.10 Earth Fault Check in a Non-earthed System
7SA6 Manual
C53000-G1176-C156-2
A request for synchro-check measurement is initiated via binary input (FNo. 2906
G
" >Sync. Start "). There is no close release. If there is, the VT mcb for the busbar
voltage is not allocated. Check whether this is the required state, alternatively check
the binary input " >FAIL:Bus VT " if necessary (FNo. 362 ).
G
Close the VT mcb of the busbar voltage is to be closed again.
G
Open the circuit breaker.
The program Usync> U-line< = Yes (address 3516 ) and Usync< U-line> =
G
No (address 3517 ) is set for the synchro-check.
A request measurement for synchro-check is initiated via binary input (FNo. 2906
G
" >Sync. Start ". The synchronism check must release closing (message " Sync.
release ", FNo. 2951 ).
If not, check all voltage connections and the corresponding parameters again care-
fully as described in Subsection 6.1.1.
G
Open the VT mcb of the feeder voltage.
Via binary input (FNo. 2906 " >Sync. Start ") initiate the measuring request. No
G
close release is given.
G
Close the VT mcb of the busbar voltage again.
Addresses 3515A to 3519 must be restored as they were changed for the test. If the
routing of the LEDs or signal relays was changed for the test, this must also be re-
stored.
The earth fault check is only necessary if the device is connected to an isolated or res-
onant-grounded system and the earth fault detection is applied. The device must
therefore be provided with the earth fault detection function according to its ordering
code (position 16 in ordering code: 2 or 3 or 6 or 7). Furthermore, address 130 Sens.
Earth Flt = Enabled must have been preset during configuration to enable this
function (according to Section 5.1). If none of this is the case, Subsection 8.3.10 is not
relevant.
The primary check serves to find out the correct polarity of the transformer connec-
tions for the determination of the earth fault direction.
DANGER!
Operations in the primary area must be performed only with plant sections
voltage-free and earthed! Perilous voltages may occur even on voltage-free
plant sections due to capacitive influence caused by other live sections.
Using the primary earth fault method a most reliable test result is guaranteed. There-
fore please proceed as follows:
G
Isolate the line and earth it on both ends. During the whole testing procedure the
line must be open at the remote end.
G
Make a test connection between a single phase and ground. On overhead lines it
can be connected anywhere, however, it must be located behind the current trans-
Installation and Commissioning
8-63
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