Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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11.6
SEL-400 Series Relays Instruction Manual Date Code 20171006
Time and Date Management
Time Quality Indications
PTP supports two power profiles and is set by the PORT 5 setting PTPPRO. The
two profiles are DEFAULT and C37.238. PTP reports the time quality through
TQUAL1, TQUAL2, TQUAL4, and TQUAL8 Relay Word bits, which are the same
bits used if IRIG-B is the time source. If PTPPRO = DEFAULT, the time quality is
reported based only on the accuracy of the master clock. If PTPPRO = C37.238, the
time quality is reported based on the accuracy of the master clock (Grandmaster timein-
accuracy) plus the inaccuracy of the network (Network timeinaccuracy). For this pro-
file, if either Grandmaster timeinaccuracy or Network timeinaccuracy is the maximum
value, the relay will set all TQUAL bits to 1.
NOTE:
If the Global setting IRIGC is
changed from NONE to C37.118, the relay
asserts TGLOBAL before completely
assessing the time-synchronization
state. The assessment completes and
TGLOBAL has the correct value
approximately 5 seconds after you make
such a settings change.
If the relay is synchronized to an IRIG-B or PTP time source, the TSYNC bit will be
set. If the quality of this synchronization is 1

s or better, then TSOK is set, indicating
this bit has sufficient accuracy for synchrophasors. TGLOBAL will assert if a high-
accuracy source is being used and the source indicates it is providing 1

s or better
accuracy, and the Global setting IRIGC = C37.118 for BNC IRIG. If the relay is syn-
chronized to IRIG-B without the quality extensions indicated by the Global setting
IRIGC, or PTP without the grandmaster clock sending announce and synchronization
messages at least every four seconds, TLOCAL bit will be asserted.
As an example of checking IRIG status, use the command TAR TIRIG to view
the relevant Relay Word bits, as shown in Figure 11.2 . Only the state of the
TIRIG and TSOK Relay Word bits are discussed in the troubleshooting steps
below. The other Relay Word bits of interest to this discussion are TUPDH,
which indicates that the relay internal clock is presently being updated by the
HIRIG source, TSYNCA, which acts as an alarm bit that asserts when the relay is
not synchronized to either an internal or an external source. TSYNCA will only
assert briefly when the HIRIG time source is connected or disconnected.
The TIRIG and TSOK Relay Word bits should be asserted (logical 1), indicating
that the relay is in the high-accuracy IRIG timekeeping mode (HIRIG).
Table 11.4 Time Quality Encoding (PTP Power Profile)
PTP v2 Power Profile (PTPPRO = C37.238)
Time_inaccuracy = Grandmaster timeinac Network
timeinaccuracy (ns) TQUAL8 TQUAL4 TQUAL2 TQUAL1 TQUAL (seconds)
Grandmaster timeinaccuracy = 4294967295 or Network
timeinaccuracy = 4294967295 1 1 1 1 Grandmaster
timeinaccuracy
+
Network
timeinaccuracy
1,000,000,000

time_inaccuracy < 10,000,000,000 1 0 1 1
100,000,000

time_inaccuracy < 1,000,000,000 1 0 1 0
10,000,000

time_inaccuracy < 100,000,000 1 0 0 1
1,000,000

time_inaccuracy < 10,000,000 1 0 0 0
100,000

time_inaccuracy < 1,000,000 0 1 1 1
10,000

time_inaccuracy < 100,000 0 1 1 0
1,000

time_inaccuracy < 10,000 0 1 0 1
100

time_inaccuracy < 1,000 0 1 0 0
10

time_inaccuracy < 100 0 0 1 1
1

time_inaccuracy < 10 0 0 1 0
time_inaccuracy = 0 0 0 0 0
=> TAR TIRIG <Enter>
* * TIRIG TUPDH TSYNCA TSOK PMDOK FREQOK
0 0 1 1 0 1 1 0
=>
Figure 11.2 Confirming the High-Accuracy Timekeeping Relay Word Bits