Technical Data
4.10 Thermal Overload Protection 49
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
311
4.10 Thermal Overload Protection 49
Setting Ranges
Calculation Method
Trip Characteristic
Drop-off to Pick-up Ratio
Tolerances
Factor k according to IEC 60255-8 0.10 to 4.00 Increments 0.01
Time Constant τ
th
1.0 min to 999.9 min Increments 0.1 min
Thermal Alarm Θ
Alarm
/Θ
Trip
50% to 100% of the trip overtemperature Increments 1 %
Current alarm element I
Alarm
for I
Nom
= 1 A 0.10 A to 4.00 A Increments 0.01 A
for I
Nom
= 5 A 0.50 A to 20.00 A
Calculation method temperature rise Maximum temperature rise of 3 phases
Average of temperature rise of 3 phases
Temperature rise from maximum current
Θ/Θ
Trip
Θ/Θ
Alarm
I/I
Alarm
Drops out with Θ
Alarm
Approx. 0.99
Approx. 0.97
Referring to k · I
N
2 % or 1 % of rated current; Class 2 according to IEC 60255-8
Ralating to tripping time 3 % or 1 s for I/(k ·I
N
) > 1.25; class 3 according to IEC 60255-8
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