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
