Schweitzer Engineering Laboratories SEL-421-4 - Figure 5.41 Swing Signature Detector Logic

5.61
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Out-of-Step Logic (Zero Settings)
Reset Conditions Function
The Reset Conditions logic corresponding to the block with the same name in
Figure 5.37 is shown in Figure 5.42.
As shown in Figure 5.37, the OSB function will reset under the following condi-
tions:
1. The SCV1 magnitude will be greater than 0.85 or the positive-
sequence impedance Z1 will be outside the starter zone for more than
0.5 s or the OST function will be enabled and Z1 will stay outside
Zone 7 for more than 30 cycles.
2. The slow derivative dSCV1_S will be smaller than 0.0026 (pu V/cyc)
for more than 10 cycles under a no-fault condition.
Figure 5.41 Swing Signature Detector Logic
AND 2
AND 4
OSBA
OSBB
OSBC
Z2G
OOSB2 = Y
Z3G
OOSB3 = Y
Z4G
OOSB4 = Y
Z5G
OOSB5 = Y
Z2P
OOSB2 = Y
Z3P
OOSB3 = Y
Z4P
OOSB4 = Y
Z5P
OOSB5 = Y
67QUBF
SPO
| dSCV1_Unflt
k–16
|
| dSCV1_Unflt
k–17
|
| dSCV1_Unflt
k–23
|
dSCV1_Unflt
max
0.05 • dSCV1_Unflt
max
0.001
2
AND 3
•
•
•
0.125
cyc
0.5
CYC
Reset Timer
0
8
CYC
SSDAND 1