Sel 411L - Page 683

P.9.37
Date Code 20151029 Protection Manual SEL-411L Relay
Monitoring and Metering
Metering
Energy Metering Accuracy
At low currents (0.1• I
NOM
), energy metering accuracy at near-unity power
factors is ±0.5 percent. At power factors of 0.5 lagging or leading, energy
metering accuracy is ±0.7 percent. At high currents (1.0 • I
NOM
), energy
metering accuracy at near unity power factors is ± 0.4 percent. At power
factors of 0.5 lagging or leading, energy metering accuracy is ±0.4 percent.
View or Reset Energy Metering Information
You can read the energy metering quantities by using a communications port,
ACSELERATOR QuickSet, or the relay front-panel LCD screen.
To reset the energy values, use the MET RE command from a
communications terminal, or use the RESET button in the
ACSELERATOR
QuickSet HMI > Meter and Control > Energy window, or answer
Y and
press ENT at the
Energy Meter submenu reset prompt on the front-panel LCD
screen. You can also reset energy metering with Global setting RST_ENE
when EDRSTC (Data Reset Control) is Y.
Energy Metering Updating and Storage
The relay updates energy values once per second. The relay also stores energy
values to nonvolatile storage once every four hours, referenced from 23:50
hours (it overwrites the previously stored value if it is exceeded). Should the
relay lose control power, it restores the energy values saved at the end of the
last four-hour period.
Time-Synchronized
Metering
The relay provides synchrophasor measurement with an angle reference
according to IEEE C37.118. The relay calculates the phasor measurement
quantities 50 or 60 times per second, depending on the nominal system
frequency contained in Global setting NFREQ.
When you issue the MET PM time command, the relay captures the
time-synchronized data for the given trigger time (specify time in 24-hour
format). The relay displays the synchrophasor data immediately after the time
trigger.
The Synchrophasor measurements are only valid when a suitable
high-accuracy IRIG-B time source is connected to the relay, as indicated by
Relay Word bit TSOK = logical 1.
The MET PM command is only available when the relay is configured for
phasor measurement functions (Global settings) and the relay is in
high-accuracy timekeeping mode.
Differential Metering
Use the MET DIF command to display differential metering information.
Information includes the communication channel status, the availability of the
87L function, whether the terminal is in stub bus, current values and angles of
the local terminal, all remote terminals, differential values and Alpha Plane
values.
The relay displays the differential metering quantities when the following is
true:
➤ The 87L communications scheme defined by the E87CH
setting (Port 87 settings) is not disabled (E87CH 
➤ The 87L element is enabled (Group settings E87L = Y).