Sel 421 - Figure 4.62 Uploading Global and Breaker Monitor Settings to the SEL-421; Table 4.9 SEL-421 Timekeeping Modes

U.4.71
Date Code 20090715 User’s Guide SEL-421 Relay
Basic Relay Operations
Configuring High-Accuracy Timekeeping
d. ACSELERATOR QuickSet responds with the second
dialog box of Figure 4.62.
If you see no error message, the new settings are loaded
in the relay.
NOTE: The Relay Editor dialog boxes
shown in Figure 4.62 are for the
SEL-421. The SEL-421-1 and SEL-421-2
dialog boxes do not contain
Automation 2 through Automation 10
setting instances.
Figure 4.62 Uploading Global and Breaker Monitor Settings to the SEL-421
Configuring High-Accuracy Timekeeping
The SEL-421 features high-accuracy timekeeping when supplied with an
IRIG-B signal. When the supplied clock signal is sufficiently accurate, the
SEL-421 can act as a Phasor Measurement Unit (PMU) and transmit
synchrophasor data representative of the power system at fixed time periods to
an external data processor. The relay can also record COMTRADE event
report data using the high-accuracy time stamp. See Synchrophasors on
page R.7.1, Oscillography on page A.3.7, and Time-Synchronized
Measurements on page A.4.1 for details on these applications.
IRIG-B
The SEL-421 has two input connectors that accept IRIG-B (Inter-Range
Instrumentation Group-B) demodulated time-code format: the IRIG-B pins of
Serial Port 1, and the IRIG-B BNC connector—see TIME Input Connections
on page U.2.45.
The IRIG-B BNC connector can be used for high-accuracy timekeeping
purposes, with up to 1 µs accuracy with an appropriate time source. Either
input can be used for general-purpose timekeeping, and the relay will have up
to 500 µs accuracy. See Table 4.9 for SEL-421 timekeeping mode details.
Table 4.9 SEL-421 Timekeeping Modes (Sheet 1 of 2)
Item Internal Clock IRIG
HIRIG (or High-
Accuracy IRIG)
Best accuracy
(condition)
Depends on last
method of setting,
or synchronization
a
500 µs (when time
source jitter is less
than 3 ms)
1 µs (when time
source jitter is less
than 500 ns, and
time-error is less
than 1 µs)
b
NOTE: The SEL-2407 Satellite
Synchronized Clock meets both the
SEL-421 accuracy and IEEE C37.118
requirements for a high-accuracy time
source.
Courtesy of NationalSwitchgear.com