Real-Time Clock - GE MI-869 Instruction Manual

CHAPTER 4: SETPOINTS

Real-time Clock

FASTPATH:
PTP Configuration
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
Path:
Setpoints > Device > Real Time Clock
The 869 is capable of receiving a time reference from several time sources in addition to its
own internal clock for the purpose of time-stamping events, transient recorders and other
occurrences within the relay. The accuracy of the time stamp is based on the time
reference that is used. The 869 supports an internal clock, SNTP, IRIG-B, and PTP IEEE 1588
as potential time references.
If two or more time sources are available, the time source with the higher priority shown in
Time Sources table is used where 1 is considered to be the highest priority. Please note
that the time source priority of PTP and IRIG-B can be swapped. If both PTP and IRIG-B are
available to the 869, by default the 869 clock syncs to PTP over IRIG-B. If PTP is not
available the 869 CPU syncs the internal clock to IRIG-B.
Table 4-1: Time Sources
Time Source
PTP (IEEE1588)
IRIG-B
SNTP
Internal Clock
* The priority of IRIG-B and PTP can be swapped.
Synchronization by IEC103, DNP, Modbus and IEC104 is not going to be issued if there is a
sync source from IRIG-B, SNTP or PTP.
Path:
Setpoints > Device > Real Time Clock > Precision Time
PORT 4(5) PTP FUNCTION
Range: Disabled, Enabled
Default: Enabled
When the port setting is selected as "Disabled," PTP is disabled on the port. The relay
does not generate, or listen to, PTP messages on the port.
PORT 4(5) PATH DELAY ADDER
Range: 0 to 60000 ns in steps of 1 ns
Default: 0 ns
The time delivered by PTP is advanced by the time value in the setting prior to the time
being used to synchronize the relay's real time clock. This is to compensate for time
delivery delays not compensated for in the network. In a fully compliant Power Profile
(PP) network, the peer delay and the processing delay mechanisms compensate for all
the delays between the grandmaster and the relay. In such networks, the setting is zero.
In networks containing one or more switches and/or clocks that do not implement both
of these mechanisms, not all delays are compensated, so the time of message arrival at
the relay is later than the time indicated in the message. The setting can be used to
approximately compensate for the delay. Since the relay is not aware of network
switching that dynamically changes the amount of uncompensated delay, there is no
setting that always completely corrects for uncompensated delay. A setting can be
chosen that reduces worst-case error to half of the range between minimum and
maximum uncompensated delay if these values are known.
Priority
1*
2*
3
4
DEVICE
4–9