Demodulated Irig-B Implementation; Sntp; Time Synchronsiation Using The Communication Protocols - GE P24DM Technical Manual

P24xM
The first four time-slots define the time in BCD (Binary Coded Decimal). Time-slots 5 and 6 are used for control
functions, which control deletion commands and allow different data groupings within the synchronisation strings.
Time-slots 7-10 define the time in SBS (Straight Binary Second of day).
8.1.1

DEMODULATED IRIG-B IMPLEMENTATION

All models have the option of accepting a demodulated IRIG-B input. This is a hardware option and it uses the
same terminals as the RP1 (or RP2 if applicable) inputs. You cannot have IRIG-B and a serial port in the same slot.
This means 20Te models cannot have both IRIG-B time synchronisation and serial communications capability. For
30TE and 40TE models however, it is possible to have IRIG-B in one slot and a serial port in another, provided this
option is ordered.
To set the device to use IRIG-B, use the setting IRIG-B Sync cell in the DATE AND TIME column. This can be set to
None (for no IRIG-B), RP1 (for the option where IRIG-B uses terminals 54 and 56) and RP2 (for the option where
IRIG-B uses terminals 82 and 84)
The IRIG-B status can be viewed in the IRIG-B Status cell in the DATE AND TIME column.
8.2

SNTP

SNTP is used to synchronise the clocks of computer systems over packet-switched, variable-latency data
networks, such as IP. SNTP can be used as the time synchronisation method for models using IEC 61850 over
Ethernet.
The device is synchronised by the main SNTP server. This is achieved by entering the IP address of the SNTP server
into the IED using the IEC 61850 Configurator software described in the settings application software manual. A
second server is also configured with a different IP address for backup purposes.
This function issues an alarm when there is a loss of time synchronisation on the SNTP server. This could be
because there is no response or no valid clock signal.
The HMI menu does not contain any configurable settings relating to SNTP, as the only way to configure it is using
the IEC 61850 Configurator. However it is possible to view some parameters in the COMMUNICATIONS column
under the sub-heading SNTP parameters. Here you can view the SNTP server addresses and the SNTP poll rate in
the cells SNTP Server 1, SNTP Server 2 and SNTP Poll rate respectively.
The SNTP time synchronisation status is displayed in the SNTP Status cell in the DATE AND TIME column.
8.3

TIME SYNCHRONSIATION USING THE COMMUNICATION PROTOCOLS

All communication protocols have in-built time synchronisation mechanisms. If an external time synchronisation
mechanism such as IRIG-B, SNTP, or IEEE 1588 PTP is not used to synchronise the devices, the time synchronisation
mechanism within the relevant serial protocol is used. The real time is usually defined in the master station and
communicated to the relevant IEDs via one of the rear serial ports using the chosen protocol. It is also possible to
define the time locally using settings in the DATE AND TIME column.
The time synchronisation for each protocol is described in the relevant protocol description section.
P24xM-TM-EN-2.1
Chapter 16 - Communications
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