Schweitzer Engineering SEL-387-0 - Figure 10.6 Percentage Restraint Differential Characteristic

10.20
SEL-387-0, -5, -6 Relay Instruction Manual Date Code 20170601
Testing and Troubleshooting
Acceptance Testing
Step 5. Purpose: Verify relay operation for faults with high neutral
current but a small difference in phase current.
Method:
a. Clear the SER by typing SER C <Enter>.
b. Connect a single current source to phase IAW4.
c. Set both current magnitude and phase angle to zero.
d. Change the 32IOP setting to 12.
e. Type TAR 32IE 9999 and confirm that the status of the
32IE Relay Word bit is logical 0.
f. Inject 0.7 A in phase IAW4 and confirm that Relay Word
bit 32IE asserts to logical 1.
g. Type TAR 50GC 10 and verify that Relay Word bit
50GC is logical 0.
h. Stop the injection and use the SER command to
confirm the assertion of Relay Word bit 32IF in
approximately 1.5 cycles after the assertion of Relay
Word bit 32IE.
i. Repeat the test injecting first in phase IBW4 and then in
phase ICW4.
Differential
The SEL-387 has several components to its differential element. Figure 10.6
gives a representation of the differential characteristic and the plot of each test.
Each test only uses Winding 1 and Winding 2 inputs. Any combination of two
winding inputs may be used for the test. The differential elements for each
winding must be enabled for each winding under test with the E87W1,
E87W2, E87W3, and E87W4 settings. Set each setting equal to “Y” to enable
the corresponding differential element.
Figure 10.6 Percentage Restraint Differential Characteristic
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