U.4.17
Date Code 20090715
User’s Guide
SEL-421 Relay
Basic Relay Operations
Making Simple Settings Changes
Making Settings Changes: Initial Global Settings
You must configure the SEL-421 for specific conditions found in the power
system where you are connecting the relay. In particular, you must set the
nominal frequency and phase rotation.
The procedure in the following steps assumes that you have successfully
established communication with the relay; see
for a step-by-step procedure. In addition, you must
be familiar with relay access levels and passwords. See
Passwords: Terminal on page U.4.9
to change the default access level
passwords.
This example jumps to a Global setting that is not at the beginning of the
Global settings list. Thus, you enter
SET G
, the setting name, and
<Enter>
.
To start at the beginning of the Global settings, simply type
SET G <Enter>
without a settings name.
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 2 => 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. Type
SET G NFREQ <Enter>
(this sets the nominal system
frequency using the
NFREQ
setting, which has options of 50
Hz and 60 Hz).
The relay responds with a terminal screen display similar to the
beginning of
.
=>>
SET G NFREQ <Enter>
Global
General Global Settings
Nominal System Frequency (50,60 Hz) NFREQ :
=
60 ?
<Enter>
System Phase Rotation (ABC,ACB) PHROT :
=
ABC ?
<Enter>
Date Format (MDY,YMD,DMY) DATE_F :
=
MDY ?
YMD <Enter>
Fault Condition Equation (SELogic Equation)
FAULT :
=
50P1 OR 51S1 OR M2P OR Z2G OR M3P OR Z3G
?
END <Enter>
•
•
•
Save settings (Y,N) ?
Y <Enter>
Saving Settings, Please Wait...........
Settings Saved
=>>
Figure 4.12
Initial Global Settings
Step 3. Accept the default settings.
a. For a 60 Hz system, simply press
<Enter>
to accept the
NFREQ existing value of 60 (Hz).
The relay presents the next setting, which is the PHROT
(phase rotation) setting.
b. Type
<Enter>
to accept the ABC phase rotation
default.
Summary of Contents for 421
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