4.76
SEL-751A Relay
Instruction Manual
Date Code 20100129
Protection and Logic Functions
Demand Metering
79SEQ :=
79RS AND 51P1P AND (logical 0) = Logical 0
The shot counter stays at shot = 1.
Thus, if there is a coincident fault between the SEL-751A and the line
recloser, the SEL-751A will operate on 51AT, 51BT, or 51CT and then
reclose once, instead of going straight to the Lockout State (shot = 1 <
last shot = 2).
As stated earlier, the reset time setting 79RSD takes the shot counter
back to shot = 0 after a sequence coordination operation increments
the shot counter. Make sure that reset time setting 79RSD is set long
enough to maintain the shot counter at shot = 1 as shown in
Reclose Supervision
Setting (79CLS)
Reclose Supervision Logic on page 4.54
Demand Metering
The SEL-751A provides demand and peak demand metering, selectable
between thermal and rolling demand types, for the following values:
➤
IA, IB, IC, phase currents (A primary)
➤
IG Residual ground current
(A primary; IG = 3I0 = IA + IB + IC)
➤
3I2 Negative-sequence current (A primary)
shows the demand metering settings. Also refer to
for other related
information for the demand meter.
The demand current level settings are applied to demand current meter outputs
as shown in
Table 4.30
Demand Meter Settings
Setting Prompt
Setting Range
Setting Name :=
Factory Default
ENABLE DEM MTR
THM, ROL
EDEM := THM
DEM TIME CONSTNT
5, 10, 15, 30, 60 min
DMTC := 5
PH CURR DEM LVL
OFF, 0.50-16.00 A
a
OFF. 0.10-3.20 A
b
a
For I
NOM
= 5 A.
b
For I
NOM
= 1 A.
PHDEMP := 5.00
PHDEMP := 1.00 b
RES CURR DEM LVL
OFF, 0.50-16.00 A
OFF, 0.10-3.2 A
GNDEMP := 1.00
GNDEMP := 0.20
3I2 CURR DEM LVL
OFF, 0.50-16.00 A
OFF, 0.10-3.2 A
3I2DEMP := 1.00
3I2DEMP := 0.20
Summary of Contents for 751A
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