GE UR Series L90, Instruction Manual, Page: 189 / 846

GE Multilin L90 Line Current Differential System 5-51
5 SETTINGS 5.2 PRODUCT SETUP
5
The relay contains a real time clock (RTC) to create timestamps 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 synchroniz-
ing time delivered to the relay. When the L30/L90 channel asymmetry function is used, the relay’s real time clock must be
synchronized to an external time source using PTP or IRIG-B, typically from a global positioning system (GPS) receiver.
The SYNCHRONIZING SOURCE setting configures the priority sequence that the relay uses to determine which of the
available external time sources synchronizes the RTC and the synchrophasor clock. A setting of None causes the RTC and
the synchrophasor clock to free-run. A setting of PP/IRIGB/PTP/SNTP, IRIGB/PP/PTP/SNTP, or PP/PTP/IRIGB/SNTP
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. When a time source fails or recovers, the relay automatically transfers synchronization as required by this setting.
See the
COMMANDS

SET DATE AND TIME
menu item section of this manual to manually set the RTC.
To enable IRIG-B synchronization, the input IRIG-B signal type must be set to DC Shift or Amplitude Modulated using the
Settings > Product Setup > Real Time Clock > IRIG-B > IRIG-B Signal Type setting. IRIG-B synchronization can be dis-
abled by making this setting None.
To configure and enable PTP and/or SNTP, or to set local time parameters (for example time zone, daylight savings), use
the following sections.
PATH: SETTINGS

PRODUCT SETUP

REAL TIME CLOCK
The relay contains a real time clock (RTC) to create timestamps 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 synchroniz-
ing time delivered to the relay. When the L30/L90 channel asymmetry function is used, the relay’s real time clock must be
synchronized to an external time source using PTP or IRIG-B, typically from a global positioning system (GPS) receiver.
The SYNCHRONIZING SOURCE setting configures the priority sequence that the relay uses to determine which of the
available external time sources synchronizes the RTC and the synchrophasor clock. A setting of None causes the RTC and
the synchrophasor clock to free-run. A setting of PP/IRIGB/PTP/SNTP, IRIGB/PP/PTP/SNTP, or PP/PTP/IRIGB/SNTP
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. When a time source fails or recovers, the relay automatically transfers synchronization as required by this setting.
See the
COMMANDS

SET DATE AND TIME
menu item section of this manual to manually set the RTC.
To enable IRIG-B synchronization, the input IRIG-B signal type must be set to DC Shift or Amplitude Modulated using the
Settings > Product Setup > Real Time Clock > IRIG-B > IRIG-B Signal Type setting. IRIG-B synchronization can be dis-
abled by making this setting None.
To configure and enable PTP and/or SNTP, or to set local time parameters (for example time zone, daylight savings), use
the following sections.
Precision Time Protocol (1588)

REAL TIME

CLOCK
SYNCRONIZING SOURCE:
None
Range: None, PP/IRIG-B/PTP/SNTP, IRIG-B/PP/PTP/
SNTP, PP/PTP/IRIG-B/SNTP
MESSAGE

PRECISION TIME

PROTOCOL (1588)
See below
MESSAGE

SNTP PROTOCOL

See below
MESSAGE

LOCAL TIME

See below