Date Code 20090730 Instruction Manual SEL-734 Meter
Section 7
Time-Synchronized Measurements
Overview
The SEL-734 Meter records power system events with very high accuracy
when it is provided with high-accuracy clock input signals, such as from a
GPS receiver. Meters placed at key substations can give you information on
power system operating conditions in real time or accumulate records when
events occur.
Based on the high-accuracy time input, the meter calculates synchronized
phasors for line currents and voltages (for each phase and for
positive-sequence). You can then perform detailed analysis and calculate load
flow from the synchrophasors.
This section presents details on these measurements as well as suggestions for
further application areas, such as the following:
➤ Meter Configuration for High-Accuracy Timekeeping
➤ Synchrophasor Measurements
➤ Power Flow Analysis
➤ State Estimation Verification
Meter Configuration for High-Accuracy Timekeeping
IRIG-B
You can connect time signals from many sources that produce the
demodulated IRIG-B (Inter-Range Instrumentation Group-B) time code
format (e.g., SEL-2032, GPS receiver). The IRIG-B signal includes codes for
time-of-day and day-of-year time stamping. The signal does not include a
code to identify the year.
To verify that the SEL-734 calendar is set to the proper year, issue the DATE
command to view or change the date. The meter stores the year in nonvolatile
memory and will maintain the proper year even if meter power cycles off and
on. The meter also maintains the time, month, and day in nonvolatile memory
while the meter power is off.
The IRIG-B serial data format consists of a one-second frame containing 100
pulses divided into fields. The meter decodes the second, minute, hour, and
day fields and sets the internal time clock upon detecting valid time data.
Maximum jitter of the input IRIG-B signal must be less than ±1 μs.
Courtesy of NationalSwitchgear.com
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