4.181
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Other Settings
The demand current level settings are applied to demand current meter
outputs, as shown in Figure 4.121. For example, when residual-ground
demand current IGD goes above the corresponding demand pickup GNDEMP,
Relay Word bit GNDEM asserts to logical 1. Use these demand current logic
outputs (PHDEM, GNDEM, and 3I2DEM) to alarm for high loading or
unbalance conditions.
m = X or Y
Figure 4.121
Demand Current Logic Outputs
The demand values are updated approximately once a second. The relay stores
peak demand values to nonvolatile storage every six hours (it overwrites the
previous stored value if it is exceeded). Should the relay lose control power, it
restores the peak demand values saved by the relay.
Demand metering peak recording is momentarily suspended when SEL
OGIC
control equation setting FAULT is asserted (= logical 1).
The differences between thermal and rolling demand metering are explained
in the following discussion.
The example in Figure 4.122 shows the response of thermal and rolling
demand meters to a step current input. The current input is at a magnitude of
zero and then suddenly goes to an instantaneous level of 1.0 per unit (a
“step”).
RES CURR DEM LVL
OFF, 0.50-16.00 A
b
OFF, 0.10-3.20 A
c
GNDEMP
m
:= OFF
GNDEMP
m
:= OFF
3I2 CURR DEM LVL
OFF, 0.50-16.00 A
b
OFF, 0.10-3.20 A
c
3I2DEMP
m
:= OFF
3I2DEMP
m
:= OFF
a
m = X or Y.
b
For I
NOM
= 5 A.
c
For I
NOM
= 1 A.
Table 4.51
Demand Meter Settings
(Sheet 2 of 2)
Setting Prompt
Setting Range
Setting Name :=
Factory Default
a
PHDEMm
Relay
Word
Bits
Demand Current
Pickup Settings
(A Secondary)
IBD
IAD
IAm
ICD
Analog
Quantities
Demand
Currents
Instantaneous
Currents
Serial Port
Command
Maximum
Current
Logic
Reset
Demand
PHDEMPm
IGD
Reset
Demand
GNDEMm
GNDEMPm
IGm
(residual)
3I2D
Reset
Demand
3I2DEMm
3I2DEMPm
3I2m
MET RD
Demand Function
Thermal (EDEM = THM)
or
Rolling (EDEM = ROL)
Demand Function
Thermal (EDEM = THM)
or
Rolling (EDEM = ROL)
Demand Function
Thermal (EDEM = THM)
or
Rolling (EDEM = ROL)
Summary of Contents for SEL-700G Series
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