Schweitzer Engineering Laboratories SEL-421-4, Instruction Manual

Page: 1136 / 1518

11.8
SEL-400 Series Relays Instruction Manual Date Code 20171006
Time and Date Management
Time Quality Indications
TIME Q Command
The TIM Q command provides details about relay timekeeping (see Table 11.3
and Table 11.4 ). The internal clock of the relay is initially calibrated at the SEL
factory. An external IRIG or PTP source is required to eliminate clock drift. The
Time Source
field provides the present high-accuracy timing input source;
entries for this line are HIRIG, HPTP, or OTHER. The
Last Update Source
reports the source from which the relay referenced the last time value measure-
ment. Entries for this line can be high-priority or low-priority sources.
Table 11.5
lists the possible
Last Update Source
values for the relay.
The
Time Mark Period
value indicates the instantaneous period in which the
relay measures the time-source inputs. The relay displays the time mark periods
showing the present time precision derived from the applied time-source signals.
The TIME Q command is also helpful for troubleshooting IRIG and PTP prob-
lems. If the
Time Mark Period
value changes significantly between successive
TIME Q commands, there may be too much noise in the time signal for the relay
timekeeping function.
=>> TIM Q <Enter>
Relay 1 Date: 02/24/2016 Time: 15:08:41.468
Station A Serial Number: 0000000000
Time Source: HPTP
Last Update Source: HPTP
Grandmaster Clock Quality
Clock Class : Synchronized with PTP timescale (6)
Time Traceable : TRUE
Clock Accuracy : Within 25 ns
Offset Log Variance : 0
Time Mark Period: 1000.000061 ms
Internal Clock Period: 19.999935 ns
=>>
Figure 11.4 Sample TIM Q Command Response
Table 11.5 Date/Time Last Update Sources
Time Input Source Mode Priority Time Source
HIRIG High Time/date from the high-accuracy IRIG-B input
SNTP Low Simple Network Time Protocol
IRIG High Time/date from the IRIG-B format time base signal
HPTP High Time/date from a high-accuracy PTP source
PTP High Time/date from a PTP source
DNP Low Time/date from the DNP3 communications port
MIRRORED BITS Low Time/date from the Mirrored Bit port
SNTP Low Time/date from SNTP server
ASCII TIME Low Time from the relay serial ports
ASCII DATE Low Date from the relay serial ports
NONV CLK Low Time/date from the nonvolatile memory clock
FRONT PANEL TIME Low Time from the front-panel TIME entry screen
FRONT PANEL DATE Low Time from the front-panel DATE entry screen