8.27
Date Code 20080213 Instruction Manual SEL-351A Relay
Breaker Monitor and Metering
Demand Metering
View or Reset
Demand Metering
Information
Via Serial Port
See MET Command (Metering Data) on page 10.18. The MET D command
displays demand and peak demand metering for the following values:
The MET RD command resets the demand metering values. The MET RP
command resets the peak demand metering values.
If setting EDEM = ROL, after resetting the demand values, there may be a
delay of up to two times the DMTC setting before the demand values are
updated.
Via Front Panel (Only on Models With LCD)
The information and reset functions available via the previously discussed
serial port commands MET D, MET RD, and MET RP are also available via
the front-panel {METER} pushbutton. See Figure 11.2.
Demand Metering
Updating and Storage
The SEL-351A updates demand values approximately every two seconds.
The relay stores peak demand values to nonvolatile storage once per day (it
overwrites the previous stored value if it is exceeded). Should it lose control
power, the relay will restore the peak demand values it saved at 23:50 hours on
the previous day.
Demand metering peak recording is momentarily suspended when SEL
OGIC
control equation setting FAULT is asserted (= logical 1). See the explanation
for the FAULT setting in Maximum/Minimum Metering on page 8.29.
Currents I
A,B,C,N
Input currents (A primary
I
G
Residual-ground current (A primary;
IG = 3I0 = IA + IB + IC)
3I
2
Negative-sequence current (A primary)
Power MW
A,B,C
Single-phase megawatts
(wye-connected voltages only)
MVAR
A,B,C
Single-phase megavars
(wye-connected voltages only)
MW
3P
Three-phase megawatts
MVAR
3P
Three-phase megavars
Courtesy of NationalSwitchgear.com
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