GE C70 Instruction Manual page 182

5.2 PRODUCT SETUP
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.
The
SYNCHRONIZING SOURCE
able 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
The
REAL TIME CLOCK EVENTS
records the RTC time before the adjustment.
To enable IRIG-B synchronization, the input
synchronization can be disabled 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.
b) PRECISION TIME PROTOCOL (1588)

PATH: SETTINGS PRODUCT SETUP
 PRECISION TIME
5
 PROTOCOL (1588)

PATH: SETTINGS PRODUCT SETUP
The UR supports the Precision Time Protocol (PTP) specified in IEEE Std 1588 2008 using the Power Profile (PP) specified
in IEEE Std C37.238 2011. This enables the relay to synchronize to the international time standard over an Ethernet net-
work that implements PP.
The relay can be configured to operate on some PTP networks that are not strictly PP. Time accuracy can be less than
specified for a PP network. Tolerated deviations from strict PP include 1) missing declaration of PP compliance in the mes-
sages, 2) connection to a network device that does not support the PTP peer delay mechanism, 3) jitter substantially
greater than 1 µs in received event messages, and 4) certain non-compliant announce and sync message update rates.
The relay implements PTP according to IEEE Std 1588 2008 and the equivalent IEC 61588:2009(E), sometimes
referred to as version 2 PTP. It does not support the previous version of the standard (version 1).
NOTE
5-58
setting configures the priority sequence that the relay uses to determine which of the avail-
menu section of this manual to manually set the RTC.
SET DATE AND TIME
setting allows changes to the date and/or time to be captured in the event record. The event
IRIG-B SIGNAL TYPE

REAL TIME CLOCK
STRICT POWER PROFILE:
Disabled
PTP DOMAIN NUMBER
MESSAGE
0
PTP VLAN PRIORITY
MESSAGE
4
PTP VLAN ID
0
 PTP PORT 1
MESSAGE


REAL TIME CLOCK
PORT 1 PTP FUNCTION:
MESSAGE
Disabled
PORT 1 PATH DELAY
MESSAGE
ADDER:
PORT 1 PATH DELAY
MESSAGE
ASYMMETRY:
C70 Capacitor Bank Protection and Control System
must be set to DC Shift or Amplitude Modulated. IRIG-B

PRECISION TIME PROTOCOL (1588)
Range: Enabled, Disabled
Range: 0 to 255
Range: 0 to 7
Range: 0 to 4095

PRECISION TIME PROTOCOL (1588)
Range: Enabled, Disabled
Range: 0 to 60 000 ns in steps of 1
00000 ns
Range: –1 000 to +1 000 ns in steps of 1
0000 ns
5 SETTINGS

PTP PORT 1(3)
GE Multilin