7.2
SEL-421 Relay Instruction Manual Date Code 20171021
Metering, Monitoring, and Reporting
Metering
Breaker 1 or Circuit Breaker 2 by entering MET BK1 or MET BK2, respec-
tively. Additionally, the MET PM command provides time-synchronized phasor
measurements at a specific time, e.g., MET PM 12:00:00.
Table 7.1 lists MET command variants for instantaneous, maximum/minimum,
demand, and energy metering. See METER on page 14.37 in the SEL-400 Series
Relays Instruction Manual and METER on page 9.4 in this manual for more
information on these and other MET command options. Other MET command
options are for viewing protection and automation variables, analog values from
M
IRRORED BITS communications, and synchronism check.
Instantaneous Metering
Use instantaneous metering to monitor power system parameters in real time.
The SEL-421 provides these fundamental frequency readings:
➤ Fundamental frequency phase voltages and currents
➤ Phase-to-phase voltages
➤ Sequence voltages and currents
➤ Fundamental real, reactive, and apparent power
➤ Displacement power factor
You can also monitor these real-time rms quantities (with harmonics included):
➤ RMS phase voltages and currents
➤ Real and apparent rms power
➤ True power factor
Both the fundamental and the rms-metered quantities are available for the LINE
input. The relay also provides both the fundamental and rms circuit breaker cur-
rents for circuit breakers BK1 and BK2.
Ta b l e 7.1 MET Com m a n d
Name
a
a
n
is 1 or 2, representing Circuit Breaker 1 and Circuit Breaker 2, respectively.
Description
MET Display Fundamental Line metering information
MET BKn Display Fundamental Circuit Breaker n metering information
MET RMS Display rms Line metering information
MET BKn RMS Display rms Circuit Breaker n metering information
MET M Display Line Maximum/Minimum metering information
MET BKn M Display Circuit Breaker n Maximum/Minimum metering information
MET RM Reset Line Maximum/Minimum metering information
MET BKn RM Reset Circuit Breaker n Maximum/Minimum metering information
MET D Display Demand Line metering information
MET RD Reset Demand Line metering information
MET RP Reset Peak Demand Line metering information
MET E Display Energy Line metering information
MET RE Reset Energy Line metering information
MET SYN Display Synchronism Check voltage and slip angle/frequency information
MET BAT Display DC Battery Monitor information
MET PM Display Phasor Measurement (Synchrophasor) metering information
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