13.3.2.3 Setting examples for IEC/UCA 61850-9-2LE and timesynchronization GUID-CEDD520A-8A13-41DF-BFF1-8A3B4C00E098 v3The IED and the Merging Units (MU) should use the same time referenceespecially if analog data is used from several sources, for example from an internalTRM and an MU, or if several physical MUs are used. Having the same timereference is important to correlate data so that channels from different sources referto the correct phase angle.When only one MU is used as an analog source, it is theoretically possible to dowithout time synchronization. However, this would mean that timestamps foranalog and binary data/events become uncorrelated. If the IED has no timesynchronization source configured, then the binary data/events will besynchronized with the merging unit. However, the global/complete time might notbe correct. Disturbance recordings then appear incorrect since analog data istimestamped by MU, and binary events use the internal IED time. It is thusrecommended to use time synchronization also when analog data emanate fromonly one MU.An external time source can be used to synchronize both the IED and the MU. It isalso possible to use the MU as a clock master to synchronize the IED from the MU.When using an external clock, it is possible to set the IED to be synchronized viaPPS,IRIG-B or PTP. It is also possible to use an internal GPS receiver in the IED(if the external clock is using GPS).1MRK 511 423-UEN A Section 13Station communicationBay control REC650 2.2 IEC 247Application manual
