Siemens siprotec 7SA6 - Thermal Overload Protection

Technical Data
10-357SA6 Manual
C53000-G1176-C133-1
10.17 Thermal Overload Protection
Setting Ranges Factor k according to IEC 60255–8 0.10 to 4.00 (steps 0.01)
Time factor τ 1.0 min to 999.9 min (steps 0.1 min)
Alarm temperaturerise Θ
alarm
/Θ
trip
50 % to 100 % related to the trip
temperaturerise (steps 1 %)
Current alarm stage I
alarm
0.10 A to 4.00 A
1
) (steps 0.01 A
1
)
1
) Secondary values based on I
N
= 1 A; for I
N
= 5 A they must be multiplied with 5.
Calculation
Method
Calculation method temperaturerise maximum temperaturerise of 3 phases
means of temperaturerise of 3 phases
temperature rise from maximum current
Tripping
Characteristic
see Figure 10-6
Drop-off
Ratios
Θ/Θ
trip
drop-off with Θ
alarm
Θ/Θ
alarm
approx. 0.99
I
/
I
alarm
approx. 0.97
Tolerances Relating to k ·
I
N
2 %, or. 10 mA
1
); class 2 % according to
IEC 60 255–8
Relating to
Tripping time 3 %, or. 1 s; class 3 % according to
IEC 60 255–8 for I/(k ·I
N
) > 1.25
1
) Secondary values based on I
N
= 1 A; for I
N
= 5 A they must be multiplied by 5.
Influencing
Quantities
relating to k ·
I
N
Auxiliary direct voltage range
0.8 ≤ U
DC
/U
NDC
≤ 1.15 1 %
Temperaturerange
–5 °C ≤ ϑ
amb
≤ 55 °C 0.5 %/10 K
Frequency range
0.95 ≤ f/f
N
≤ 1.05 1 %
t τ
I
k
I
N
⋅
-------------


2
I
pre
k
I
N
⋅
-------------


2
–
I
k
I
N
⋅
-------------


2
1
–
-------------------------------------------------
ln ⋅
=
Tripping characteristic
t Tripping time
τ Temperature rise time factor
I
Load current
I
pre
Previous load current
k Setting factor according to
IEC 60255–8
I
N
Rated current of protected object
Meaning of abbreviations:
for (
I
/ k · I
N
) ≤ 8