10-14 Testing and Troubleshooting Date Code 20080110
SEL-387E Instruction Manual
For example, if 51P1P = 2.2 A, 51P1C = U3, and 51P1TD = 4.0, we
can use the equation below to calculate the expected operating time
for M = 3 (applied current equals M•51P1P = 6.6 A):
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−
+=
1M
88.3
0963.0•TDtp
2
33.2tp
seconds
Step 2.
Purpose: Set the Sequential Events Recorder to record the element timing.
Method: Use
SET R SER1 <Enter>
to set SER1 equal to the element pickup and
time-out Relay Word bits (i.e., 51P1, 51P1T). When prompted, set SER2,
SER3, and SER4 to NA. Save the settings.
Step 3.
Purpose: Connect and apply a single-current test source at a level that is M times
greater than the pickup (i.e., 2.2 • M = 6.6 A for this example).
Method: Connect a single-current test source as shown in
Figure 10.6. Turn on the
single-current test source for the winding under test at the desired level.
Step 4.
Purpose: Verify the operation times.
Method: Type
SER <Enter>
to view the sequential events records. The assertion
and deassertion of each element listed in the SER1, 2, 3, and 4 settings is
recorded. Subtract the time from the assertion of the pickup (i.e., 51P1) to
the assertion of the time-delayed element (i.e., 51P1T).
SER C
clears the
sequential events records.
Step 5.
Purpose: Repeat the test for each definite-time and inverse-time overcurrent
element, for each winding.
Method: Repeat Steps 1 through 4 for each time element listed in
Table 10.2 for
each winding. Remember to set the SER for the appropriate elements and
apply current to the appropriate winding.
Note:
If the time-overcurrent element induction-disk reset emulation is
enabled (i.e., 51P1RS = Y), the element under test may take some
time to reset fully. If the element is not fully reset when you run a
second test, the time to trip will be lower than expected. To reset
all time-overcurrent elements before running additional tests, enter
the
RESET <Enter>
command from the relay serial port.
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