Time Synchronisation
Accuracy
The accuracy of the used SNTP server and the excellence of its reference clock influences the accuracy of the
protection relay's clock.
For further information about accuracy refer to chapter Specifications.
With each transmitted time information, the SNTP server also sends information about its accuracy:
Stratum: The stratum indicates over how many interacting NTP-Servers the used SNTP server is connected to
an atomic or radio controlled clock.
Precision: This indicates the accuracy of the system time provided by the SNTP server.
Additionally the performance of the connected network (traffic and data package transmission times) has an
influence on the accuracy of the time synchronisation.
Recommended is a locally installed SNTP server with an accuracy of
≤200 µsec. If this cannot be realised, the
connected server's excellence can be checked in the menu [Operation/Status Display/TimeSync]
:
The server quality gives information about the accuracy of the used server. The quality should be GOOD or
SUFFICIENT. A server with BAD quality should not be used, because this could cause fluctuations in time
synchronisation.
The network quality gives information about the network's load and data package transmission time. The quality
should be GOOD or SUFFICIENT. A network with BAD quality should not be used, because this could cause
fluctuations in time synchronisation.
Using two SNTP Servers
When configuring two SNTP servers, the device selects the server with the lower stratum value, because this
generally provides a more precise time synchronisation. If the servers have the same stratum value, the device
selects the server with the better precision. It does not matter, which of the servers is configured as server 1 or
server 2.
When the last used server fails, the device automatically switches to the other server. Should the first server
recover after some time, the device switches back to this (better) server automatically.
SNTP Commissioning
Activate the SNTP time synchronisation by means of the menu [Device Para/ Time/ TimeSync]:
Select »
SNTP« in the time synchronisation menu.
Set the IP address of the first server in the SNTP menu.
Set the IP address of the second server, if available.
Set all configured servers to “active”.
270
MRU4
DOK-HB-MRU4-2E
