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Section 20
Basic IED functions
For IEDs using IEC/UCA 61850-9-2LE in "mixed mode" a time synchronization from an external
clock is recommended to the IED and all connected merging units. The time synchronization
from the clock to the IED can be PTP, optical PPS or IRIG-B. For IEDs using IEC/UCA
61850-9-2LE from one single MU as analog data source, the MU and IED still need to be
synchronized to each other. This could be done by letting the MU supply a PPS signal to the IED
or by supplying a PPS signal from the IED to the MU, by using a GTM.
Out of these, LON and SPA contains two types of synchronization messages:
•
Coarse time messages are sent every minute and contain complete date and time, that is
year, month, day, hour, minute, second and millisecond.
•
Fine time messages are sent every second and comprise only seconds and milliseconds.
The selection of the time source is done via the corresponding setting.
It is possible to select more than one time source, in which case one is backup for the other.
The time synchronization source with the best calculated time-quality is automatically
selected. For instance, if both GPS and IRIG-B are selected and both sources have the required
accuracy, optical IRIG-B with IEEE1344 will be automatically selected as the time
synchronization source. Or if GPS and SNTP are selected, when the GPS signal quality is bad,
the IED will automatically choose SNTP as the time-source.
If PTP is activated, the device with the best accuracy within the synchronizing group will be
selected as the source. For more information about PTP, see the Technical manual.
IEEE 1588 (PTP)
PTP according to IEEE 1588-2008 and specifically its profile IEC/IEEE 61850-9-3 for power
utility automation is a synchronization method that can be used to maintain a common time
within a station. This time can be synchronized to the global time using, for instance, a GPS
receiver. If PTP is enabled on the IEDs and the switches that connect the station are
compatible with IEEE 1588, the station will become synchronized to one common time with an
accuracy of under 1us. Using an IED as a boundary clock between several networks will keep
1us accuracy on three levels or when using an HSR, 15 IEDs can be connected in a ring without
losing a single microsecond in accuracy.
20.13.2
Setting guidelines
All the parameters related to time are divided into two categories: System time and
Synchronization.
20.13.2.1
System time
The time is set with years, month, day, hour, minute, second and millisecond.
20.13.2.2
Synchronization
The setting parameters for the real-time clock with external time synchronization are set via
local HMI or PCM600. The path for Time Synchronization parameters on local HMI is Main
menu/Configuration/Time/Synchronization. The parameters are categorized as Time
Synchronization (TIMESYNCHGEN) and IRIG-B settings (IRIG-B:1) in case that IRIG-B is used as
the external time synchronization source.
TimeSynch
When the source of the time synchronization is selected on the local HMI, the parameter is
called
TimeSynch . The time synchronization source can also be set from PCM600. The setting
alternatives are:
444
1MRK 505 370-UEN D
IP15089-1 v3
M11348-119 v6
M11348-143 v5
M11348-167 v17
Busbar protection REB670
Application manual
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