GE Multilin 350 Series Instruction Manual page 227

CHAPTER 6: SETPOINTS
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
THERMAL MDL FUNC
Range: Disabled, Latched Alarm, Alarm, Trip
Default: Disabled
The thermal capacity will be displayed on the relay even if the Thermal Model Function is
set to "Disabled. The output relay #1 "Trip" will operate only if the function is selected as
a Trip and the thermal capacity value of any phase is over 100%. The LED "ALARM" will
turn on when the function is selected as a Trip or Alarm if the thermal capacity value of
any phase is over the Thermal MDL Alarm setting. This LED will turn off when the
thermal capacity value of all phases is below 97% of the Thermal MDL Alarm setting. If
Latched Alarm is selected as a function setting, the LED "ALARM" will flash if the thermal
capacity value of any phase is over the Thermal MDL Alarm setting, and will stay "ON"
when the thermal capacity value of all phases is below 97% of the Thermal MDL Alarm
setting, until the reset command is initiated. The output relay #1 "Trip" will not operate if
the Latched Alarm or Alarm setting is selected. Any of the output relays 3 to 6 can be
selected to operate when the Thermal Model Function is selected as Latched Alarm,
Alarm or Trip.
The thermal capacity values are stored in memory and can be cleared either by using
the "Clear Thermal Capacity" command, or by cycling relay control power.
THERMAL MDL PKP
Range: 0.05 to 20 x CT in steps of 0.01 x CT
Default: 1.00 x CT
This setting sets the level of phase current above which the thermal model starts timing
out the time-to-trip per the logarithmic formula above.
THERMAL MDL ALARM
Range: 70.0 to 110.0% in steps of 0.1%
Default: 80.0%
This setting sets the alarm level for the accumulated thermal capacity above which the
element generates an alarm.
HEAT TIME CONSTANT (τ
H
Range: 3.0 to 600.0 min in steps of 0.1 min
Default: 6.0 min
This time constant is used to compute the thermal capacity when the thermal capacity
at each time-step is greater than the one computed in the previous time-step.
COOL TIME CONSTANT (τ
C
τ
Range: 1.00 to 6.00 x in steps of 0.01 x
H
τ
Default: 2.00 x
H
This time constant is used to compute the thermal capacity when the thermal capacity
at each time-step is less than the one computed in the previous time-step.
OUTPUT RELAY 3 to 6
Range: Do Not Operate, Operate
Default: Do Not Operate
Any or all of output relays 3 to 6 can be selected to operate upon a Thermal Model
condition. The selection of relay outputs operation is available no matter whether the
Latched Alarm, Alarm, or Trip function is selected.
)
)
τ
H
S3 PROTECTION
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