Device; Real-Time Clock - GE 845 Instruction Manual

DEVICE

Device

Real-time Clock

4–10
Figure 4-6: Device Display Hierarchy
Path:
Setpoints > Device > Real Time Clock
The 845 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 845 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
Table 5-1 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 845, by default the 845 clock syncs to PTP over IRIG-B. If PTP is not available the
845 CPU syncs the internal clock to IRIG-B.
Table 4-1: Time Sources
Time Source
PTP (IEEE1588)
Priority
1*
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS