Alstom MiCOM P546 - 7. GPS SYNCHRONIZATION; 7.1.1 Commission the P594; 7.1.2 P594 optical signal strength at P54 x relay; 7.1.3 Check synchronization signal at P54 x relay

P54x/EN CM/La4 Commissioning
(CM) 10-36 MiCOM P543, P544, P545 & P546
CM
7. GPS SYNCHRONIZATION
The P54x has a feature whereby the timing information used to align the local and remote
current vectors used in the phase differential algorithm can be very accurately synchronized
via the global positioning satellite (GPS) system. If specified, a P594 GPS synchronizing
unit is employed to decipher GPS signals and provide the P54x relay with a suitable
synchronizing signal.
If the P54x is using GPS synchronization to enhance the phase current differential
protection, then the associated P594 unit will need to be commissioned in accordance with
the relevant commissioning instructions. The P594 commissioning instructions can be found
in the CM chapter of the P594 Technical Manual (P594_EN M/D22).
If P594 synchronizing units are not employed, proceed to section 8.
7.1.1 Commission the P594
The
commissioning instructions and record sheets for the P594 GPS synchronization are
available in the P594 Technical Manual, P594/EN CM/D22. The P594 should be
commissioned as per the instructions for a P594 being used to synchronize a P54x relay.
7.1.2 P594 optical signal strength at P54x relay
With the interconn
ecting optical fiber connected to the optical transmitter of the P594
prescribed by the scheme, and with the P594 in ‘Test Cycle Mode’, at the P54x end,
measure the received signal strength. The value should be in the range -16.8 dBm to
-25.4 dBm. Record the value.
7.1.3 Check synchronization signal at P54x relay
Disable th
e ‘Test Cycle Mode’ at the P594. Connect the fiber from the P594 to the GPS
synchronizing input of the P54x relay. Enable GPS synchronization in [201A: PROT
COMMS/IM64, GPS Sync Enabled] menu cell of the relay. Check that the relay is
recognizing the GPS synchronization in [0507 MEASUREMENTS 4, Channel Status] of the
relay
If the GPS synchronization signal is being received, with the communications configured for
loopback, the ‘Local GPS’ and Remote GPS’ bits should both be set in the channel status
such that the display reads **11******** (* is ‘don’t care’ state for the purpose of this test).
7.1.4 Check GPS failure condition
Disco
nnect the fiber from the P594 and check that the display reverts to **00********.
7.1.5 Restore GPS
Re
connect the fiber and check again that the display reads **11********.