Sel 551 - Figure 3.18 Sequence Coordination between the SEL-551 and a Line Recloser; Figure 3.19 Operation of SEL-551 Shot Counter for Sequence Coordination with Line Recloser (Additional Settings Example 1)

3.35
Date Code 20110408 Instruction Manual SEL-551 Relay
Relay Elements and Logic
Reclosing Relay
Figure 3.18 Sequence Coordination Between the SEL-551 and a Line
Recloser
Presume that the line recloser is set to operate twice on the fast curve and then
twice on the slow curve. The slow curve is allowed to operate after two fast
curve operations because the fast curves are then inoperative for tripping. The
SEL-551 phase time-overcurrent element 51P1T is coordinated with the line
recloser fast curve. The SEL-551 phase time-overcurrent element 51P2T is
coordinated with the line recloser slow curve.
q Fault occurs beyond line recloser; w fault cleared by line recloser fast curve; e line recloser recloses into fault; r fault
cleared by line recloser slow curve.
Figure 3.19 Operation of SEL-551 Shot Counter for Sequence Coordination With Line Recloser (Additional
Settings Example 1)
Fast Curve
(Line Recloser)
51P1
Slow Curve
(Line Recloser)
t
I
F
I
51P1T
(SEL-551)
51P2T
(SEL-551)
SEL-551
R
Line Recloser
I
F
79SEQ = 79RS*51P1
SH0 + SH1
SH1
SH0
Shot Counter 0 1 2 3
4
qw ew e r e r