Time Synchronization of the Line Differential Protection Measured Values with Millisecond Accuracy
The measured values of the line differential protection for the various line ends are synchronized with each
other with microsecond accuracy via the mechanisms of the protection interface. The protection interface
displays this state with the RAISING indication
Protection interface synchronized
.
If communications problems occur, it is possible that the measured values may not be properly synchronized.
In this case, the protection interface generates the CLEARED indication
Protection interface
synchronized
. The line differential protection is blocked. This state can be corrected only by manual inter-
vention.
NOTE
You can reset the synchronization of the protection interface directly in the device. Proceed as follows:
Device functions > x Device protection comm. > Protection interface y > Reset synchron.
Synchronization via GPS Second Pulse
Millisecond-accurate synchronization of the devices (1*10E-06 s), connected via protection interfaces, can
take place via a high-precision GPS second pulse at the time-synchronous port G for special differential protec-
tion applications or synchrophasor measuring devices. As a result, the transmission time of the communica-
tion route can be measured and displayed separately in the directions forward and reverse. This ensures that
the maximum responsivity can be obtained during differential protection, even if transmission times are
unbalanced in the communication networks. Different transmission times are insignificant for the transmis-
sion of protection data with a protection communication of type 2.
Log Off the Device
A device can be logged off for protection-function tests, system inspections, or disconnection of a feeder for
operational reasons. The device that is logged off no longer participates in the distributed functionality and is
therefore no longer a component of the topology. The protection functions are still in operation for the other
end or ends.
The following conditions are necessary for a successful logoff of the device from the point of view of protec-
tion communication:
•
The protection topology is not in a transient state and is stable in operation without switchovers.
•
The local device is one of the 2 token masters if there is a chain topology. The token masters are the
devices at the ends of the chain.
•
The circuit breaker must be open and current must not be flowing.
NOTE
If one of these conditions is not fulfilled, the device cannot be logged off.
You can find more detailed information in chapter 3.8.4 Device Logoff.
System Functions
3.5 Protection Communication
SIPROTEC 5, Overcurrent Protection, Manual 121
C53000-G5040-C017-8, Edition 07.2017
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