The default
Max temperature
setting is 105°C. This value is chosen since even
though the IEC 60076-7 standard recommends 98°C as the maximum allowable
temperature in long-time loading, the standard also states that a transformer can
withstand the emergency loading for weeks or even months, which may produce
the winding temperature of 140°C. Therefore, 105°C is a safe maximum temperature
value for a transformer if the
Max temperature
setting value is not given by the
transformer manufacturer.
4.1.7.6 Signals
Table 333: T2PTTR 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
BLOCK BOOLEAN 0=False Block signal for acti-
vating the blocking
mode
AMB_TEMP FLOAT32 0 The ambient temper-
ature used in the cal-
culation
Table 334: T2PTTR Output signals
Name Type Description
OPERATE BOOLEAN Operate
START BOOLEAN Start
ALARM BOOLEAN Thermal Alarm
BLK_CLOSE BOOLEAN Thermal overload indicator.
To inhibite reclose.
4.1.7.7 Settings
Table 335: T2PTTR Group settings (Basic)
Parameter
Values (Range) Unit Step Default Description
Env temperature
Set
-50...100 °C 1 40 Ambient tempera-
ture used when
no external temper-
ature measurement
available
Temperature rise 0.0...200.0 °C 0.1 78.0 End temperature
rise above ambient
Max temperature 0.0...200.0 °C 0.1 105.0 Maximum tempera-
ture allowed for the
transformer
Operate tempera-
ture
80.0...120.0 % 0.1 100.0 Operate tempera-
ture, percent value
Alarm temperature 40.0...100.0 % 0.1 90.0 Alarm temperature,
percent value
Table continues on the next page
1MRS757644 H Protection functions
620 series
Technical Manual
349
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