GE B90 Instruction Manual page 292

PRODUCT SETUP
The relay contains a real time clock (RTC) to create time stamps for communications protocols as well as for historical data,
such as event records and oscillography. When the relay restarts, the RTC initializes from an onboard battery-backed
clock, which has the same accuracy as an electronic watch, approximately ±1 minute per month (~23 ppm). Once the RTC
is synchronized with the Precision Time Protocol (PTP), IRIG-B, or SNTP, its accuracy approaches that of the synchronizing
time delivered to the relay. While the RTC is not synchronized via PTP or IRIG-B, or the relay determines that it has an offset
possibly greater than 10 µs from the international time standard, the
activated.
The
SYNCHRONIZING SOURCE
the priority sequence of the time synchronization source, to determine which of the available external time sources to use
for time synchronization. A setting of None causes the RTC and the synchrophasor clock to free-run, and the clock can be
changed from the front panel or from communications protocols. A setting of PP/IRIG-B/PTP/Other, IRIG-B/PP/PTP/Other, or
PP/PTP/IRIG-B/Other causes the relay to track the first source named that is enabled and operational, or free-run if none of
these are available. Here, PP means a time source that is strictly compliant with PP, PTP means a time source that is not
strictly compliant with PP, and Other means any less precise source (SNTP, IEC 103, IEC 104, Modbus, or DNP). When a time
source fails or recovers, the relay automatically transfers synchronization as required by this setting.
When the relay does not have the IEEE 1588 software option and this setting does not display, it uses IRIG-B when enabled
and operational, then failing that SNTP when configured and operational, and otherwise it free-runs unless the clock is
changed from the front panel or from communications protocols.
Setup for IRIG-B is illustrated in the Installation chapter.
For the Other protocols, whenever a time synchronization message is received through any of the active protocols, the B90
clock updates. However, given that IEC 60870-5-103, IEC 60870-5-104, Modbus, and DNP are low-accuracy time
5
synchronization methods, avoid their use for synchronization when better accuracy time protocols, such as IRIG-B and PTP,
are active in the system. If IRIG-B or PTP is used to update the relay clock, the other protocols (such as SNTP) are not
allowed to update, even if active.
See the
COMMANDS  SET DATE AND TIME
The
REAL TIME CLOCK EVENTS
records the RTC time before the adjustment. A Date/Time Changed event is generated when:
• The real time clock changed from SNTP/PTP/IRIG-B and the time difference is more than one second
• The real time clock changed from the front panel or via Modbus register. The relay always generates this event
regardless of the time difference.
• The Daylight Saving Time (DST) setting gets enabled and the current relay time is already in the DST zone
• The real time clock enters or leaves DST
To enable IRIG-B synchronization, the input
synchronization can be disabled by making this setting None.
Clocks can be synchronized locally among several relays using the computer time. When using a time source, such as IRIG-
B, the time is overwritten eventually by the time source. To synchronize clocks among UR devices:
1. In the EnerVista software, expand the main menu in the Online Window area and select the Synchronize Devices
entry. The window opens. The software prompts to acknowledge any offline devices.
2. Click the Synchronize Devices button at the top of the window, and confirm the action at the prompt. The devices
assume the time of the computer being used.
To configure and enable PTP and/or SNTP, or to set local time parameters (for example time zone, daylight savings), use the
following sections.
5.3.8.2 Precision time protocol (1588)
SETTINGS  PRODUCT SETUP  REAL TIME CLOCK  PRECISION TIME PROTOCOL (1588)
 PRECISION TIME
 PROTOCOL (1588)
5-100
 LOCAL TIME


setting displays when the relay includes the IEEE 1588 software option. The setting configures
menu section of this manual to manually set the RTC.
setting allows changes to the date and/or time to be captured in the event record. The event
IRIG-B SIGNAL TYPE
STRICT POWER

PROFILE: Disabled
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
See below
CLOCK UNSYNCHRONIZED
must be set to DC Shift or Amplitude Modulated. IRIG-B
Range: Enabled, Disabled
CHAPTER 5: SETTINGS
FlexLogic operand is