ABB REC670 Applications Manual page 598

Section 23
Basic IED functions
592
easily performed and a more accurate view of the actual sequence of events can be
obtained.
Time-tagging of internal events and disturbances are an excellent help when
evaluating faults. Without time synchronization, only the events within one IED
can be compared with each other. With time synchronization, events and
disturbances within the whole network, can be compared and evaluated.
In the IED, the internal time can be synchronized from the following sources:
• BIN (Binary Minute Pulse)
• DNP
• GPS
• IEC103
• SNTP
• IRIG-B
• SPA
• LON
• PPS
• IEEE 1588 (PTP)
For IEDs using PMU functionality, only PTP, GPS or IRIG-B or a combination of
both GPS and IRIG-B is allowed.
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.
1MRK 511 401-UEN A
Bay control REC670 2.2 IEC
Application manual