U.6.27
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Testing and Troubleshooting
Checking Relay Operation
Step 4. Display the 50Q1 Relay Word bit on the front-panel LCD
screen. Access the front-panel LCD MAIN MENU. Highlight
RELAY ELEMENTS and press
{ENT}
. Press
{ENT}
to go to
the ELEMENT SEARCH submenu of
. Use the
navigation keys to highlight 5 and then press
{ENT}
to enter
characters in the text input field. Enter the 0, Q, and 1
characters in turn. Highlight ACCEPT and press
{ENT}
. The
relay displays the screen containing the 50Q1 element, as
shown in
.
Figure 6.21
ELEMENT SEARCH Screen.
Figure 6.22
RELAY ELEMENTS Screen Containing Element 50Q1.
Step 5. Connect a test source to the relay. Set the current output of a
test source to zero output level. Connect a single-phase current
output of the test source to the IAW analog input (see
Secondary Circuits on page U.2.5
).
Step 6. Test the element. Increase the current source to produce a
current magnitude greater than 1.00 A secondary in the relay.
You will see that the 50Q1 element state changes on the LCD
screen from 50Q1 = 0 to 50Q1 = 1.
Negative-Sequence
Directional Element
for Phase Faults
The SEL-421 Relay features a phase directional element (represented by
Relay Word bits F32P/R32P) to supervise the phase distance elements and to
control phase directional elements. The negative-sequence directional
element, F32Q/R32Q, is a part of the phase directional element, F32P/R32P.
Whenever the negative-sequence directional element asserts, the phase
directional element asserts.
The relay also contains a ground directional element, F32G/R32G, for
directional control of the ground distance elements and ground overcurrent
elements. For more information on directional elements, see
Directional Element on page R.1.21 in the Reference Manual
, and
Protection Application Examples in the Applications Handbook
The SEL-421 Relay calculates the negative-sequence impedance Z2 from the
magnitudes and angles of the negative-sequence voltage and current.
defines this function (the ‘c’ in Z2c indicates
“calculated”).
ELEMENT SEARCH
A B C D E F
G H I J K L
M N O P Q R
S T U V W X
Y Z 0 1 2 3
4 5 6 7 8 9
-
ACCEPT BACKSPACE
PRESS TO SEARCH
RELAY ELEMENTS
SEARCH
ROW 26
ROW 27
67Q4 =0
* =0
67Q3 =0
* =0
67Q2 =0
* =0
67Q1 =0
* =0
50Q4 =0
67Q4T =0
50Q3 =0
67Q3T =0
50Q2 =0
67Q2T =0
50Q1 =0
67Q1T =0
Summary of Contents for SEL-421
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