10-18 Testing and Troubleshooting Date Code 20080110
SEL-387E Instruction Manual
breakers are brought to the relay. These two inputs are for the same physical winding, whose
current is the phasor sum of the two inputs.
The test configuration is that shown in
Figure 10.6, with two sources delivering current to the
same phase of Windings 1 and 2.
The test below is for element 51PC1, using Windings 1 and 2 inputs. Set the pickup, curve, and
time-dial values for this element as desired. The pickup should be set fairly low, at about one or
two amperes. Disable the complementary 51NC1 element by setting 51NC1P to OFF.
Step 1.
Purpose: Determine the expected time delay for the overcurrent element.
Method: Execute the
SHOWSET
command via the relay front panel or serial port
and verify the element settings (i.e.,
SHO 51PC1P <Enter>
). The pickup
is 51PC1P, the curve type is 51PC1C, and the time-dial is 51PC1TD.
Calculate the time delay to pickup (tp). Inverse-time elements are
calculated using three element settings and the operating time equations
shown in
Section 3: Protection Functions
. TD is the time-dial setting
(i.e., 51PC1TD), and M is the applied multiple of pickup current.
For example, if 51PC1P = 2.2 A, 51PC1C = U3, and 51PC1TD = 4.0, we
can use the equation below to calculate the expected operating time for
M = 3 (applied current equals M • 51PC1P = 6.6 A):
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−
+=
1M
88.3
0963.0•TDtp
2
ondssec33.2tp
=
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., 51PC1, 51PC1T). When prompted, set
SER2, SER3, and SER4 to NA. Save the settings.
Step 3.
Purpose: Connect and apply two single-current test sources to create sufficient
current to operate the 51PC1 element.
Method: Connect two single-current test sources as shown in
Figure 10.6. Set the
IAW1 current at some fixed value, such as 10 A at angle zero degrees.
Set the IAW2 current at 10 A at 180 degrees. Because the phasor sum is
zero, nothing will happen.
Execute the
TAR F 22
command. Relay Word bits 51PC1 and 51PC1T
will appear in the second row of LEDs, in the A and B positions, during
the tests. Before the test, LED C should be lit, representing bit 51PC1R
(reset).
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