Schweitzer Engineering Laboratories SEL-421-4 - Figure 5.55 Out-Of-Step Trip Logic (EOOS = Y1)

5.71
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Out-of-Step Logic (Zero Settings)
Figure 5.55 shows the logic for the different EOOST settings (EOOST = N, I, O,
C) when EOOS = Y1. Setting EOOST = N turns gate AND 1 off. When AND 1
turns off, all three outputs (OSTI, OST, and OSTO) are also turned off.
Figure 5.55 Out-of-Step Trip Logic (EOOS = Y1)
EOOST = I
EOOST = N
OSB_I
EOOST = O or C
EOOST = 0 (On-the-Way-Out) EOOST = C (On-the-Way-Out with counts)
EOOST = O
EOOST = C
R7T
X7T
X6T
RR6
RL6
R6T
RR7
RL7
OST
OSTI OSTO
AND 1
OSTFF1
X
7
T
X
6
T
R R
6
R
L
6
R
6
T
R R
7
R
L
7
R
7
T
FF1
S
R
Q
OSTFF3
FF3
S
R
Q
Pole Slip
Counter
Ck
Reset
OSTFF2
FF2
S
R
Q
OSTFF5
FF5
S
R
Q
OSTFF4
FF4
S
R
Q
OSTFF6
FF6
S
R
Q