10.22
SEL-387-0, -5, -6 Relay
Instruction Manual
Date Code 20170601
Testing and Troubleshooting
Acceptance Testing
O87P Differential Element Pickup
Step 1. Purpose: Verify the expected restrained differential element
minimum pickup setting.
Method: Execute the
SHO
command via the relay front panel
or serial port and verify the setting (i.e.,
SHO O87P <Enter>
).
This value is in per unit of tap.
Step 2. Purpose: Calculate the required current to pick up the
restrained differential element.
Method:
a. Calculate the expected pickup for the 87R element by
multiplying the O87P setting by the TAP1, TAP2,
TAP3, or TAP4 setting and the compensation constant
A shown in
. The CT connection
compensation settings W1CTC, W2CTC, W3CTC, and
W4CTC determine the A constant for the calculations.
b. Use the corresponding TAP
n
and W
n
CTC settings for
the winding under test.
Step 3. Purpose: Display the appropriate Relay Word bit on the front-
panel LEDs.
Method: Execute the
TARGET
command (i.e.,
TAR F 87R
<Enter>
). The SEL-387 now displays the state of several
differential elements in the second row of the front-panel
LEDs. The 87R bit is the right-most LED.
Step 4. Purpose: Connect and ramp a single current test source until the
appropriate LED illuminates.
Method:
a. Connect a single current test source as shown in
b. Turn on the current test source for the winding under
test, and slowly increase the magnitude of current
applied until the 87R element asserts. Note the
magnitude of the current applied. It should equal the
value calculated in
, ±5% ±0.02 I
NOM
.
Step 5. Purpose: Repeat the test for each phase for each winding if
desired.
Method:
a. Repeat
through
b. Remember to view the appropriate TARget and apply
current to the appropriate winding. The computer
terminal will display the LED labels from left to right
when the
TAR F
command is issued.
Summary of Contents for SEL-387-0
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