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
ACSELERATOR software, or the front panel. For more information on
SEL-421 Relay metering, see Metering on page A.2.28 in the Applications
Handbook.
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 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
page 4.10 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 Making
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
Figure 4.21. 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 Figure 4.22 to
PTRY and change PTRY to 2000, if needed. Type
END<Enter> to finish this settings session. Answer Y
<Enter> to the save settings prompt.
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