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5.2 PRODUCT SETUP
b) PRECISION TIME PROTOCOL (1588)
PATH: SETTINGS
PRODUCT SETUP
PRECISION TIME
PROTOCOL (1588)
PATH: SETTINGS
PRODUCT SETUP
5
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
PTP is a protocol that allows multiple clocks in a network to synchronize with one another. It permits synchronization accu-
racies better than 1 ns, but this requires each and every component in the network achieve very high levels of accuracy and
a very high baud rate, faster than normally used for relay communications. When operating over a generic Ethernet net-
work, time error may amount to 1 ms or more. PP is a profile of PTP which specifies a limited subset of PTP suitable for use
in power system protection, control, automation and data communication applications, and thereby facilitates interoperabil-
ity between different vendor's clocks and switches. PP specifies a worst-case delivered time error of less than 1 µs over a
16-hop network.
In a PTP system and in a PP system, the clocks automatically organize themselves into a master-slave synchronization
hierarchy with the "best" clock available making itself the "grandmaster" at the top of the hierarchy; all others make them-
selves "slaves" and track the grandmaster. Typically the grandmaster clock receives its time from GPS satellites or some
other link to the international time standard. If the grandmaster fails, the next "best" clock available in the domain assumes
the grandmaster role. Should a clock on starting up discover it is "better" that the present grandmaster, it assumes the
grandmaster role and the previous grandmaster reverts to slave.
Time messages issued by the grandmaster are delayed as they pass through the network both due to the finite speed of
the signal in the interconnecting fiber or wire, and due to processing delays in the Ethernet switches. Each clock and switch
implementing PP measures the propagation delay to each of its PP neighbors, and compensates for these delays in the
time received. Each network device implementing PP measures the processing delay it introduces in each time message
and compensates for this delay in the time it transmits. As a result, the time delivered to end-devices such as the UR are
5-48
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:
D30 Line Distance Protection System
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
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