Schweitzer Engineering Laboratories SEL-421-4 - Table 7.5 Demand and Peak Demand Metering Quantities-LINE; Table 7.6 Energy Metering Quantities-(LINE)

7.6
SEL-421 Relay Instruction Manual Date Code 20171021
Metering, Monitoring, and Reporting
Metering
Demand Metering
See Demand Metering on page 7.6 in the SEL-400 Series Relays Instruction
Manual for a complete description of how demand metering works. The SEL-421
provides demand metering and peak demand metering for the LINE quantities.
Table 7.5 lists the quantities used for demand and peak demand metering.
Energy Metering
Energy is the power consumed or developed in the electric power system mea-
sured over time. See Energy Metering on page 7.6 in the SEL-400 Series Relays
Instruction Manual for complete details of energy metering computation, view-
ing, and control. Energy metering is available only for the LINE data. Table 7.6
lists the energy metering quantities that the relay displays.
Frequency f
Circuit breaker rms current I
rms
Three-phase true real power 3P
rms
Three-phase reactive power 3Q
1
Three-phase true apparent power 3U
rms
a
Sequence components are maximum values only.
Table 7.4 Maximum/Minimum Metering Quantities—Voltages, Currents,
Frequency, and Powers (Sheet 2 of 2)
Metered Quantity Symbol
Table 7.5 Demand and Peak Demand Metering Quantities—LINE
Symbol Units Description
I
rms
A, primary Input rms current
I
Grms
a
a
(IG = 3I0 = IA + IB + IC).
A, primary Residual ground rms current
3I
2
A, primary Negative-sequence current
P

MW, primary Single-phase real powers (with harmonics)
Q

MVAR, primary Single-phase reactive powers
U

MVA, primary Single-phase total powers (with harmonics)
3P MW, primary Three-phase real power (with harmonics)
3Q MVAR, primary Three-phase reactive power
3U MVA, primary Three-phase total power (with harmonics)
Table 7.6 Energy Metering Quantities—(LINE)
Analog Quantity Units Description
MWHOUT MWh, primary Single-phase energy export
MWHIN MWh, primary Single-phase energy import
MWHT MWh, primary Single-phase energy total
3MWHOUT MWh, primary Three-phase energy export
3MWHIN MWh, primary Three-phase energy import
3MWH3T MWh, primary Three-phase energy total