Sel 411L - Figure 11.10 Single-Terminal Test

P.11.26
SEL-411L Relay Protection Manual Date Code 20151029
Testing and Troubleshooting
Checking Relay Operation
terminal. Adjust the phase angle to be 180 degrees out-of-phase
with the A-phase current.
10. Confirm that the A-phase element is picked up.
11. Increase the A-phase current until the element drops out.
12. Confirm that the dropout current is
Equation 11.11
Blocking Angle Check
13. Inject an A-phase current with a magnitude equal to the
minimum pickup (Step 6).
14. Inject a B-phase current with a magnitude equal to the
minimum pickup (Step 6). Adjust the phase angle at this
terminal to be 180 degrees out-of-phase with the A-phase
current.
15. Confirm that the value of k and alpha is 1.0  180° at both
relays and for all three phases and no relays have operated.
16. Rotate the angle of the A-phase current counter-clockwise until
the A-phase element picks up. Record this value as 1.
17. Rotate the angle of the A-phase current clockwise until the
element drops out and picks up again. Record this value as 2.
18. Confirm that
Equation 11.12
19. Repeat Step 1–Step 17 for the phase B, C, Q, and G elements.
Figure 11.10 shows the injected currents for the particular
element under test. Use the TEST 87L command to select a
different element for the test.
Figure 11.10 Single-Terminal Test
Step 20. Use the TEST 87L command to exit Test Mode.
Loopback Testing
A loopback test can be carried out in order to isolate a problem with a
communications channel. For example, assume that the system shown in
Figure 11.11 is experiencing a high-packet loss alarm. A loopback test is
carried out at Relay 1 by applying a loopback at Terminal 1. During this test,
I
DROPOUT
Tap
1
87LPR S
--------------------------
=
3601 287LPAS=–+
Local
Current
Remote
Current
Single Terminal, A Element Test
IA
IB
87TOUT
87L
A
Local
Current
Remote
Current
Single Terminal, B Element Test
IB
IC
87TOUT
87L
B
Local
Current
Remote
Current
Single Terminal, C Element Test
IC
IA
87TOUT
87L
C
Local
Current
Remote
Current
Single Terminal, Q Element Test
IA
IB
87TOUT
87L
Q
Local
Current
Remote
Current
Single Terminal, G Element Test
IA
IB
87TOUT
87L
G