Hitachi Relion 670 Series Applications Manual page 375

1MRK506375-UEN Rev. N
Procedure to bring protections back into service and enable maintenance
of a faulty merging unit
1. Disconnect bay
2. Energize binary input, block of bay. Protections are now back in service.
3. Maintenance of the merging unit can start.
Procedure to bring bay back into service after maintenance of a merging
unit
1. Energize merging unit.
2. De-energize binary input block of bay. Protections are now back in service.
3. Reconnect bay.
18.3.3 Bay out of service for maintenance
When a bay need maintenance and has energized merging unit connected, it is always a risk to get
unplanned interruptions in the auxiliary power supply which may lead to unwanted blocking of
protections.
This is resolved by setting the merging unit "out of service" by setting the parameter "Operation" in
"Main menu/Configuration/Analog modules/Mu....", to "Out of service" instead of "In service". The
merging unit will look like it is in normal operation from the protection point of view, with perfect 0-
value input values, comparable to a TRM that is not connected. A hint will be shown to inform that a
merging unit is out of service.
18.3.4 Setting guidelines
Merging Units (MUs) have several settings on local HMI under:
• Main menu /Configuration /Analog modules /MUx:92xx . The corresponding settings are also
available in PST (PCM600).
• Main menu /Configuration /Communication /Merging units configuration /MUx:92xx . The
corresponding settings are also available in ECT (PCM600).
XX can take value 01–12.
18.3.4.1 Specific settings related to the IEC/UCA 61850-9-2LE communication
The process bus communication IEC/UCA 61850-9-2LE has specific settings, similar to the analog
inputs modules.
If there are more than one sample group involved, time synch is mandatory. If there is no time
synchronization, the protection functions will be blocked due to condition blocking.
CTStarPointx: These parameters specify the direction to or from object. See also section
current channels".
SyncLostMode: If this parameter is set to Block and the IED hardware time synchronization is lost or
the synchronization to the MU time is lost, the protection functions in the list
conditional blocking. If this parameter is set to BlockOnLostUTC, the protection functions in list
blocked if the IED hardware time synchronization is lost or the synchronization of the MU time is lost
or the IED has lost global common synchronization (i.e. GPS, IRIG-B or PTP). SYNCH output will be
set if IED hardware time synchronization is lost. MUSYNCH output will be set if either of MU or IED
hardware time synchronization is lost.
Railway application RER670
Application manual
Binary signals over LDCM are transmitted as valid and processed normally even when
analog signals are transmitted as invalid due to loss of communication or loss of time
synchronization.
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Section 18
Station communication
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