U.4.33
Date Code 20090715 User’s Guide SEL-421 Relay
Basic Relay Operations
Examining Metering Quantities
Examining Metering Quantities
The SEL-421 features high-accuracy power system metering. You can view
fundamental and rms quantities by using a communications terminal,
ACSELERATOR QuickSet, or the front panel. For more information on
SEL-421 metering, see Metering on page A.2.26.
View Metering:
Terminal
The procedure in the following steps shows how to use a terminal or terminal
emulation computer program to view power system metering. In this example,
you connect specific voltages and currents for a 5 A, 60 Hz relay. Scale these
quantities appropriately for your particular relay. For more information on
testing the relay and making test connections, see Section 6: Testing and
Troubleshooting.
This example assumes that you have successfully established communication
with the relay (see Making an EIA-232 Serial Port Connection on page U.4.5).
In addition, you must be familiar with relay access levels and passwords (see
Changing the Default Passwords: Terminal on page U.4.9 to change the
default access level passwords).
Step 1. Prepare to control the relay at Access Level 2.
a. Using a communications terminal, type ACC <Enter>.
b. Type the Access Level 1 password and press <Enter>.
You will see the Access Level 1 => prompt.
c. Type the 2AC <Enter> command.
d. Type the correct password to go to Access Level 2.
You will see the Access Level 2 =>> prompt.
Step 2. Set the relay to a nominal operation mode.
a. Use a terminal to perform the initial global settings
relay setup in Making Settings Changes: Initial Global
Settings on page U.4.17.
b. Set the relay for 60-Hz operation, ABC phase rotation.
Step 3. Set the relay for a basic voltage and current configuration (see
Figure 4.23). Use the terminal to set global settings ESS := 1.
a. Type SET G ESS TERSE <Enter>.
b. Type 1 <Enter> if the ESS setting is not 1.
c. Type END <Enter> to finish this settings session.
d. Answer Y <Enter> to the save settings prompt.
=>>SET G ESS TERSE <Enter>
Global
Current and Voltage Source Selection
Current and Voltage Source Selection (Y,N,1,2,3,4) ESS := N ? 1 <Enter>
Line Current Source (IW,COMB) LINEI := IW ? END <Enter>
Save settings (Y,N) ? Y <Enter>
Saving Settings, Please Wait...........
Settings Saved
=>>
Figure 4.23 Setting ESS: Terminal
NOTE: If the relay is in service,
disable any output circuits (such as
trip and close) to avoid an
unintended relay operation caused
by test signals.
Courtesy of NationalSwitchgear.com
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