Earth Fault Check In A Non-Earthed System - Siemens siprotec 7SA6 User Manual

Installation and Commissioning
8.3.9

Earth Fault Check in a Non-earthed System

8-52
q
For the synchro-check the program 8V\QF 8OLQH! = <HV (address ) and
6<1&&+(&. = <HV (address $) is set.
q
Open the VT mcb of the busbar voltage.
q
A request for synchro-check measurement is initiated via binary input (FNo.  
"!6\QF 6WDUW"). There is no close release. If there is, the VT mcb for the busbar
voltage is not allocated. Check whether this is the required state, alternatively check
the binary input "!)$,/ %XV 97" if necessary (FNo. ).
q
Close the VT mcb of the busbar voltage is to be closed again.
q
Open the circuit breaker.
q
The program 8V\QF! 8OLQH = <HV (address ) and 8V\QF 8OLQH! =
1R (address ) is set for the synchro-check.
q
A request measurement for synchro-check is initiated via binary input (FNo.  
"!6\QF 6WDUW". The synchronism check must release closing (message "6\QF
UHOHDVH", FNo.  ).
If not, check all voltage connections and the corresponding parameters again
carefully as described in Subsection 6.1.1.
q
Open the VT mcb of the feeder voltage.
q
Via binary input (FNo.   "!6\QF 6WDUW") initiate the measuring request. No
close release is given.
q
Close the VT mcb of the busbar voltage again.
Addresses $ to  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
restored.
The earth fault check is only necessary if the device is connected to an isolated or
resonant-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 
6HQV (DUWK )OW = (QDEOHG must have been preset during configuration to enable
this function (according to Section 5.1). If none of this is the case, Subsection 8.3.9 is
not relevant.
The primary check serves to find out the correct polarity of the transformer
connections for the determination of the earth fault direction.
DANGER!
Primary measurements must only be carried out on disconnected and grounded
equipment of the power system. Danger to life exists even on disconnected
equipment because of capacitive coupling from other energized equipment of
the power system!
Using the primary earth fault method a most reliable test result is guaranteed.
Therefore please proceed as follows:
7SA6 Manual
C53000-G1176-C133-1