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G.9
Date Code 20070117
Instruction Manual
SEL-351-5, -6, -7 Relay
Setting SEL
OGIC
Control Equations
SEL
OGIC
Control Equations
If maximum phase current is
above
the phase instantaneous overcurrent
element pickup setting 50P1P (see
), Relay Word bit 50P1 is in the
following state:
50P1 = 1 (logical 1)
With SH0 = 1 and 50P1 = 1, the ANDed combination results in:
50P1 * SH0 = 1 * 1 = 1 (logical 1)
and an instantaneous trip results. This logic is commonly used in fuse saving
schemes for distribution feeders.
If the reclosing relay shot counter advances to shot = 1 for the reclose that
follows the trip, Relay Word bit SH0 is in the following state:
SH0 = 0 (logical 0)
If maximum phase current is
above
the phase instantaneous overcurrent
element pickup setting 50P1P for the reoccurring fault, Relay Word bit 50P1
is in the following state:
50P1 = 1 (logical 1)
With SH0 = 0 and 50P1 = 1, the ANDed combination results in:
50P1 * SH0 = 1 * 0 = 0 (logical 0)
and no trip results from phase instantaneous overcurrent element 50P1.
A trip will eventually result if time-overcurrent element 51PT or 51GT times
out. If residual ground time-overcurrent element 51GT times out, Relay Word
bit 51GT is in the following state:
51GT = 1 (logical 1)
When shot = 1, SH0 = 0 and the result is:
TR =
51PT + 51GT + 50P1 * SH0
= 0 + 1 + 1 * 0 = 0 + 1 + 0 = 1
and a time-delayed trip results from residual ground time-overcurrent element
51GT.
Set an Output Contact for Tripping
To assert output contact
OUT101
to trip a circuit breaker, make the following
SEL
OGIC
control equation output contact setting (see
OUT101 =
TRIP
All SEL
OGIC
Control
Equations Must Be
Set
All SEL
OGIC
control equations must be set one of the following ways (they
cannot be “blank”):
➤
Single Relay Word bit (e.g., 52A = IN101)
➤
Combination of Relay Word bits (e.g., TR = 51PT + 51GT +
50P1 * SH0)
➤
Directly to logical 1 (e.g., 67P1TC = 1)
➤
Directly to logical 0 (e.g., TRCOMM = 0)
Summary of Contents for SEL-351-5
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