U.4.31
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Basic Relay Operations
Examining Metering Quantities
Examining Metering Quantities
The SEL-421 Relay features high-accuracy power system metering. You can
view fundamental and rms quantities by using a communications terminal, the
AC
SEL
ERATOR
software, or the front panel. For more information on
SEL-421 Relay metering, see
Metering on page A.2.28 in the Applications
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
Troubleshooting in the User’s Guide
This example assumes that you have successfully established communication
with the relay; see
Making an EIA-232 Serial Port Connection on page 4.6
for
a step-by-step procedure. In addition, you must be familiar with relay access
levels and passwords. See
Changing the Default Passwords: Terminal on
to change the default access level passwords.
Step 1. Prepare to control the relay at Access Level 2. Using a
communications terminal, type
ACC<Enter>
. Type the Access
Level 1 password and press
<Enter>
. You will see the =>
action prompt. Type the
2AC<Enter>
command, and then type
the correct password to go to Access Level 2. You will see the
=>> action prompt.
Step 2. Set the relay to a nominal operation mode. Use a terminal to
perform the initial global settings relay setup in
Settings Changes: Initial Global Settings on page 4.19
. Set the
relay for 60-Hz operation, ABC phase rotation.
Step 3. Set the relay for a basic voltage and current configuration. See
. Use the terminal to set global settings ESS := 1.
Type
SET G ESS
TERSE<Enter>
. Type
1<Enter>
if the ESS
setting is not 1. Type
END<Enter>
to finish this settings
session. 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 4.21
Setting ESS: Terminal.
Step 4. Set CT and PT ratios. Use the terminal to confirm that Group 1
setting CTRW := 200 (the current transformer W-input ratio),
and PTRY := 2000 (the potential transformer Y-input ratio).
Type
SET CTRW TERSE<Enter>
. If the CTRW setting is
not 200, type
200<Enter>
. Proceed as shown in
PTRY and change PTRY to 2000, if needed. Type
END<Enter>
to finish this settings session. Answer
Y
<Enter>
to the save settings prompt.
Summary of Contents for SEL-421
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