5.6
SEL-2414 Transformer Monitor Instruction Manual Date Code 20130214
Metering and Monitoring
Metering
All maximum and minimum metering points include values, date, and time that
they occurred. The analog quantities from Table 5.8 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. The following minimum thresholds must also be met:
To reset maximum/minimum meter values, issue the MET RM command. All
maximum and minimum metering values are stored to nonvolatile memory four
times per day and within one minute of the maximum and minimum metering
values being reset.
Demand Metering
Two methods exist for measuring power system current and power demand.
These methods are thermal demand metering and rolling demand metering
Figure 5.5 and Figure 5.6 illustrate the step input response of the two demand
measuring methods with setting DMTC (demand meter time constant) at 15 min-
utes. The following values are supported if the appropriate cards are installed:
The demand metering settings (in Table 5.11) are available via the SET com-
mand (see Table 6.1 and also Demand Metering on page SET.1 at the end of
Section 6). Also refer to METER Command (Metering Data) on page 7.18, and
MET Demand/Peak Demand Metering on page 7.20.
Depending on enable setting EDEM, these demand and peak demand values are
thermal demand or rolling demand values. The differences between thermal and
rolling demand metering are explained in the following subsection.
Power
P kW Real Power
Q kVAr Reactive Power
S kVA Apparent Power
Other
FREQ Hz System Frequency
Table 5.9 Max/Min Minimum Thresholds
Metering Values Threshold
IA, IB, IC, and IN Greater than 3% of nominal CT rating
IG IA, IB, and IC all must be over their thresholds
VA, VB, VC 7.5 V
VAB, VBC, VCA 13 V
Power Values IA, IB, IC, and (VA, VB, VC or VAB, VBC, VCA) all must be
over their thresholds
Table 5.8 Maximum/Minimum Meter Values (Sheet 2 of 2)
Values Units Description
Tab le 5.1 0 De m an d Meter Valu es
Values
Units Description
Currents (4 ACI) Currents (3 ACI/3 AVI)
IA, IB, IC, IN IAX, IBX, ICX A Line
IG IGX A Residual Ground
3I2 3I2X A Negative-Sequence
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