Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

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11.5
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Time and Date Management
Time Quality Indications
3. PTP high quality (PTP_OK = 1)
4. PTP nominal quality (PTP_TIM = 1)
5. IRIG-B BNC nominal quality (BNC_TIM = 1)
6. IRIG-B serial port nominal quality (SER_TIM = 1)
The TIME command indicates what source is being used. This is also available
in the analog quantity CUR_SRC as shown in Table 11.2 .
If IRIG-B and PTP are not available, then the time can be set via any low-priority
time source: SNTP, DNP3,
TIME and DATE commands, front-panel set date/
time, and extended M
IRRORED
B
ITS
.
Time Quality Indications
Analog Quantities and Relay Word Bits
You can check the status of timekeeping by checking the relevant analog quanti-
ties or relay word bits. Once a time source is connected, wait at least 20 seconds
to allow for a solid synchronization to take place.
If you are using a time source that provides time-quality information (IRIG-B
with C37.118 or PTP), then the presently reported time quality is available via
the TQUAL analog quantity and the TQUAL1, TQUAL2, TQUAL4, and
TQUAL8 Relay Word bits.
Table 11.3 and Table 11.4 show how these are
encoded for IRIG and the two supported PTP Profiles.
Table 11.2 CUR_SRC Encoding
Source CUR_SRC value
BNC IRIG-B 1
Serial Port IRIG-B 2
PTP 4
None of the above 8
Table 11.3 Time Quality Encoding (PTP Default Profile or IRIG)
PTP v2 Default Profile Or IRIG (PTPPRO = Default)
Master Clock Accuracy (ns) TQUAL8 TQUAL4 TQUAL2 TQUAL1 TQUAL (seconds)
Clock failure, time not reliable 1 1 1 1 1038
10 seconds 1 0 1 1 10
1 second 1 0 1 0 1
100 milliseconds 1 0 0 1 0.1
10 milliseconds 1 0 0 0 0.01
1 millisecond 0 1 1 1 0.001
100 microseconds 0 1 1 0 0.0001
10 microseconds 0 1 0 1 0.00001
1 microsecond 0 1 0 0 0.000001
100 nanoseconds 0 0 1 1 0.0000001
10 nanoseconds
a
a
This does not apply to PTP default Profile.
0 0 1 0 0.00000001
1 nanosecond
a
0 0 0 1 0.000000001