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The thermal replica is calculated individually for each phase. Address 4206 CALC.
Calculating the
METHOD decides whether the highest of the three calculated temperatures (Θ max) or
overtemperature
their arithmetic average (Average Θ) or the temperature calculated from the phase
with maximum current (Θ from Imax) should be decisive for the thermal alarm and
tripping stage.
Since an overload usually occurs in a balanced way, this setting is of minor impor-
tance. If unbalanced overloads are to be expected, however, these options lead to dif-
ferent results.
Averaging should only be used if a rapid thermal equilibrium is possible in the protect-
ed object, e.g. with belted cables. If the three phases are, however, more or less ther-
mally isolated (e.g. single conductor cables or overhead lines), one of the maximum
settings should be chosen at any rate.
2.14.3 Settings
The table indicates region-specific presettings. Column C (configuration) indicates the
corresponding secondary nominal current of the current transformer.
Addr.
Parameter
4201
Ther. OVERLOAD
4202
K-FACTOR
4203
TIME CONSTANT
Θ ALARM
4204
4205
I ALARM
4206
CALC. METHOD
2.14.4 Information List
No.
Information
1503
>BLK ThOverload
1511
Th.Overload OFF
1512
Th.Overload BLK
1513
Th.O/L ACTIVE
1515
Th.O/L I Alarm
Th.O/L Θ Alarm
1516
1517
Th.O/L Pickup
1521
Th.O/L TRIP
7SD610 Manual
C53000-G1176-C145-4
C
Setting Options
OFF
ON
Alarm Only
0.10 .. 4.00
1.0 .. 999.9 min
50 .. 100 %
1A
0.10 .. 4.00 A
5A
0.50 .. 20.00 A
Θ max
Average Θ
Θ from Imax
Type of In-
formation
SP
>BLOCK Thermal Overload Protection
OUT
Thermal Overload Protection OFF
OUT
Thermal Overload Protection BLOCKED
OUT
Thermal Overload Protection ACTIVE
OUT
Th. Overload: Current Alarm (I alarm)
OUT
Th. Overload Alarm: Near Thermal Trip
OUT
Th. Overload Pickup before trip
OUT
Th. Overload TRIP command
2.14 Thermal Overload Protection
Default Setting
OFF
Thermal overload protec-
tion
1.10
K-Factor
100.0 min
Time Constant
90 %
Thermal Alarm Stage
1.00 A
Current Overload Alarm
Setpoint
5.00 A
Θ max
Method of Acquiring Tem-
perature
Comments
Comments
197
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