The thermal overload protection provides information that makes temporary
overloading of cables and lines possible. The thermal overload protection estimates
the conductor temperature continuously. This estimation is made by using a
thermal model of the line/cable that is based on the current measurement.
If the temperature of the protected object reaches a set warning level, a signal is
given to the operator. This enables actions in the power system to be done before
dangerous temperatures are reached. If the temperature continues to increase to the
maximum allowed temperature value, the protection initiates a trip of the protected
line.
4.1.5.6 Signals
Table 230: T1PTTR Input signals
Name Type Default Description
I_A SIGNAL 0 Phase A current
I_B SIGNAL 0 Phase B current
I_C SIGNAL 0 Phase C current
ENA_MULT BOOLEAN 0=False Enable Current multiplier
BLK_OPR BOOLEAN 0=False Block signal for operate outputs
TEMP_AMB FLOAT32 0 The ambient temperature used in the calculation
Table 231: T1PTTR Output signals
Name
Type Description
OPERATE BOOLEAN Operate
START BOOLEAN Start
ALARM BOOLEAN Thermal Alarm
BLK_CLOSE BOOLEAN Thermal overload indicator. To inhibite reclose.
4.1.5.7 Settings
Table 232: T1PTTR Group settings
Parameter
Values (Range) Unit Step Default Description
Env temperature Set -50...100 °C 1 40 Ambient temperature used when no
external temperature measurement
available
Current multiplier 1...5 1 1 Current multiplier when function is used
for parallel lines
Current reference 0.05...4.00 xIn 0.01 1.00 The load current leading to Temperature
raise temperature
Temperature rise 0.0...200.0 °C 0.1 75.0 End temperature rise above ambient
Time constant 60...60000 s 1 2700 Time constant of the line in seconds.
Table continues on next page
Section 4 1YHT530004D05 D
Protection functions
230 615 series
Technical Manual
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