Technical Data
4.23 Thermal Overload Protection
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
626
4.23
Thermal Overload Protection
Setting Ranges
Calculation Method
Tripping Characteristic
Dropout to Pickup 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 Overload
I
Alarm
for
I
N
= 1 A
0.10 A to 4.00 A
Increments 0.01 A
for
I
N
= 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 nominal current; Class 2 % according to
IEC 60255-8
Referring to tripping time
3 % or 1 s for
I
/(k ·
I
N
) > 1,25; class 3 acc. to IEC 60255-8