ABB Relion 670 Series Applications Manual page 488

Section 20
Basic IED functions
If PTP is not used, use the same synchronization method for the HwSyncSrc as the merging unit
provides. For instance, if the merging unit provides PPS as synchronization, use PPS as HwSyncSrc. If
either PMU or LDCM in GPS-mode is used, that is, the hardware and software clocks are connected to
each other, HwSyncSrc is not used and other means to synchronize the merging unit to the IED is
required. Either FineSyncSource is set to the same source that the merging unit uses, or the PPS output
from the GTM module is used to synchronize the merging unit. If the PPS output from the GTM module is
used to synchronize the merging unit and PTP is not used, the IED does not know how the merging unit
is synchronized and the parameter SyncLostMode must be set to NoBlock.
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If the IED is used together with a merging unit and no time synchronization is available,
for example, in the laboratory test, the IED will synchronize to the SV data
stream. During the re-synchronization, the protection functions will be blocked once a
second for about 45 ms, and this will continue for up to 10 minutes. To avoid this,
configure PTP (IEEE 1588) to On for the access point where the merging unit is
configured.
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1MRK 505 370-UUS Rev. K
Busbar protection REB670
Application manual