Date Code 20070117
Instruction Manual
SEL-351-5, -6, -7 Relay
Section 4
R.Instruction Manual
Loss-of-Potential, Load Encroachment,
and Directional Element Logic
Loss-of-Potential Logic
The loss-of-potential (LOP) logic operates as shown in
q
w
to
,
, and
e
to
r
.
Figure 4.1
Loss-of-Potential Logic
Inputs into the LOP logic are:
Inputs
Description
3PO
three-pole open condition
(indicates circuit breaker open condition see
)
V
1
positive-sequence voltage (V secondary)
I
1
positive-sequence current (A secondary)
I
0
zero-sequence current (A secondary)
V
0
zero-sequence voltage (V secondary) {wye-connected PTs}
LOP
ELOP = Y
ELOP = Y1
ELOP = Y or Y1
3PO
V1GOOD
Wye-Connected PTs
Delta-Connected PTs
VNOM
V
1
, I
1
, I
0
V
0
V
2
Loss-of-Potential
Logic
Relay
Word
Bits
Relay
Word
Bit
Settings
q
w
e
r
Summary of Contents for SEL-351-5
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