10
SEL Application Guide 2015-12 Date Code 20150401
Step 5. Slowly increase the local current until 87TOUT asserts. The pickup value should
be within ±5 percent of the value calculated by (6):
PICKUP
I [magnitude of the local current]•87LkR=
(6)
where:
87LkR is 87LPR for an 87LA, 87LB, or 87LC test; 87LQR for an 87LQ test;
and 87LGR for an 87LG test.
Block Angle Setting Check
Step 1. Connect the proper local and remote current sources.
Step 2. Set the magnitudes and angles of local and remote currents as determined in Step 2
and Step 3 in the previous subsection (Radius Setting Check).
Step 3. Confirm that 87TOUT is deasserted.
Step 4. Rotate the angle of the local current in the counter-clockwise direction until
87TOUT asserts. Record this angle as ANG1.
Step 5. Reset the angle of the local current to 0 degrees.
Step 6. Rotate the angle of the local current in the clockwise direction until 87TOUT
asserts. Record this angle as ANG2.
Step 7. Assuming that the angles are measured as 0 to +180 degrees and 0 to –180 degrees,
respectively, check that the block angle is set within ±5 percent of the angle
determined by (7):
(7)
where:
87LkA is 87LPA for an 87LA, 87LB, or 87LC test; 87LQA for an 87LQ test;
and 87LGA for an 87LG test.
Repeat the preceding steps for each of the differential elements.
Note: You can also test the extended security differential settings of the relay by choosing the
87TESTS = S option in test mode, which switches the normal radius and angle settings
to secure mode settings.
CONCLUSION
This application guide provides the tools to test the characteristics of the differential elements of
the SEL-411L relay in test mode.
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