Sel 751A - Maximum and Minimum Metering; Table 5.4 Maximum;Minimum Meter Values; Figure 5.5 Device Response to the METER RE Command

5.6
SEL-751A Relay Instruction Manual Date Code 20100129
Metering and Monitoring
Metering
To reset energy meter values, issue the METER RE command as shown in
Figure 5.5.
=>>MET RE <Enter>
Reset Metering Quantities (Y,N)? Y <Enter>
Reset Complete
=>>
Figure 5.5 Device Response to the METER RE Command
Maximum and
Minimum Metering
Maximum and minimum metering allows you to determine maximum and
minimum operating quantities such as currents, voltages, power, analog input
quantities, RTD quantities and frequency. Table 5.4 lists the max/min
metering quantities.
All maximum and minimum metering values will have the date and time that
they occurred. The analog quantities from Table 5.4 are checked
approximately every 0.5 seconds and, if a new maximum or minimum value
occurs, this value is saved along with the date and time that the maximum or
minimum value occurred. Maximum and minimum values are only checked if
relay element FAULT is deasserted (no fault condition exists) for at least one
second.
Additionally, the following minimum thresholds must also be met:
➤ Current values I
A
, I
B
, I
C
, and I
N
: 3% of the nominal CT rating.
➤ Current value I
G
: I
A
, I
B
, and I
C
all must be above their
thresholds.
➤ Voltage values (phase and phase-to-phase): 7.5 V and 13 V,
respectively.
➤ Power values (real, reactive, and apparent): All three currents
(I
A
, I
B
, I
C
) and all three voltages (V
A
, V
B
, V
C
or V
AB
, V
BC
, V
CA
)
must be above their thresholds.
Table 5.4 Maximum/Minimum Meter Values
Relay Option Max/Min Meter Values
Base Model Maximum and minimum line currents I
A
, I
B
, I
C
, and I
N
(core-balance ground fault current) magnitudes (A)
Maximum and minimum I
G
(residual ground fault current)
magnitude (A)
Maximum and minimum system frequency (Hz)
With Voltage Option V
AB
, V
BC
, V
CA
or V
AN
, V
BN
, V
CN
, and V
S
(if ordered)
magnitudes (V)
Maximum and minimum real, reactive and apparent
3-phase power (kW, kVAR, kVA)
With RTD option or
SEL-2600 RTD Module
Maximum and minimum RTD temperatures (°C)
With analog input option Maximum and minimum analog input values (engineering
units)