Sel 411L - Page 736

P.11.22
SEL-411L Relay Protection Manual Date Code 20151029
Testing and Troubleshooting
Checking Relay Operation
14. If there are two breakers at the remote terminal then repeat
Step 9–Step 13 using the second current input of the remote
relay.
Blocking Angle Check
15. Inject an A-phase current with a magnitude equal to the
minimum pickup (Step 6) at the local terminal.
16. Inject an A-phase current with a magnitude equal to the
minimum pickup (Step 6) at a remote terminal. Adjust the
phase angle at this terminal to be 180 degrees out-of-phase with
the local terminal.
17. Confirm that the value of k and alpha is 1.0  180 degrees at
both relays and for all three phases and no relays have operated.
18. Rotate the angle of the A-phase local current counter-clockwise
until the A-phase element picks up. Record this value as1.
19. Rotate the angle of the A-phase local current clockwise until
the element drops out and picks up again. Record this value as
2.
20. Confirm that
Equation 11.3
21. For three- and four-terminal applications, repeat Step 4–Step 20
using other relays as the remote terminal.
22. Repeat Step 1–Step 21 using other relays as the local terminal.
23. Repeat Step 1–Step 22 for B-phase and C-phase. Use the TEST
87L command to select a different element for the test.
24. Use the TEST 87L command to exit Test Mode.
87LQ
1. For this test, a balanced three-phase current with an ACB
rotation is applied to the relay. This approach is not chosen
because the 87LQ is intended to detect balanced ACB faults.
Instead it is done in order to exercise all three of the relay
inputs and to simplify the determination of the injection values.
2. Use the TEST 87L command to enter Test Mode.
3. Ensure that relay outputs are supervised or isolated. See Test
Precautions for details.
4. When prompted, select a characteristic test and multiterminal
mode. Choose the Q element and normal or secure depending
on the particular settings to be tested.
Pickup Check
5. Begin the test with no current injected at any terminal.
6. Inject a balanced three-phase current with an ACB rotation at
the local terminal. Increase the magnitude until the Q element
operates.
360 1 2–+ 87LPA S=