Schweitzer Engineering SEL-387-0, Instruction Manual

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10.26
SEL-387-0, -5, -6 Relay Instruction Manual Date Code 20170601
Testing and Troubleshooting
Acceptance Testing
constant must be used to achieve the exact curve point on
which we have based the calculations. The TAP
n settings can
be different for the two windings.
Step 5. Purpose: Calculate the initial current for Winding 2 for this test.
Method: Calculate the Winding 2 initial current by multiplying
the Winding 2 expected current calculated above by 110
percent.
IAW2 (initial) = 1.1 • IAW2 (from step 4)
Step 6. Purpose: Connect a single current test source to A-phase of
Winding 1 and a single current test source to A-phase of
Winding 2. Ramp down Winding 2 current until the appropriate
LED illuminates.
Method:
a. Connect the two current test sources as shown in
Figure 10.5 .
b. Turn on the current test source for A-phase of
Winding 1 (
IAW1
) at the value calculated above and set
the phase angle to zero degrees .
c. Turn on the current test source for A-phase of
Winding 2 ( IAW2 ) at the calculated starting current and
set the phase angle at 180 degrees .
d. Slowly decrease the magnitude of current
IAW2
until the
87R element asserts. Note the magnitude of the current
applied. It should equal the value calculated in
Step 4
±5% ±0.02 I
NOM
.
Step 7. Purpose: Repeat the test for each phase for each winding
combination if desired.
Method:
a. Repeat Step 1 through Step 6 for each phase.
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.
Second Harmonic Blocking
Step 1. Purpose: Verify the second-harmonic restraint percentage.
Method:
a. Execute the SHOW command via the relay front panel
or serial port and verify the percentage of fundamental
current that the magnitude of second-harmonic current
must exceed for differential restraint and that
HRSTR = N.
b. Enter SHO PCT2 <Enter> .
Step 2. 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.
NOTE:
This test requires a current
source capable of generating second-
harmonic current. This example tests
the second-harmonic blocking
function.