Thermal Overload Protection
Setting Ranges / Increments
K-Factor accord. 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 excessive
temperature
Increments 1 %
Current Overload Ι
Alarm
for Ι
Nom
= 1 A
0.10 A to 4.00 A Increments 0.01 A
for Ι
Nom
= 5 A
0.50 A to 20.00 A
Extension kτ Factor when Machine Stopped 1.0 to 10.0 relative to the time
constant for the machine running
Increments 0.1
Emergency Time T
Emergency
10 s to 15000 s Increments 1 s
Nominal Overtemperature (for Ι
Nom
)
40 °C to 200 °C Increments 1 °C
Trip Characteristic
Formula for primary values:
Trip Characteristic curve for Ι / (k ⋅ Ι
Nom
) ≤8
with
t Trip time in minutes
τ
th
Heating-up time constant
Ιn
Actual load current
Ι
pre
Preload current
k Setting factor per IEC 60255-8
Ι
Nom
Nominal current for the protected object
Dropout Ratios
Θ/Θ
Trip
Θ/Θ
Alarm
Ι/Ι
Alarm
Drops out with Θ
Alarm
approx. 0.99
approx. 0.97
Tolerances
Referring to k ·
Ι
Nom
Referring to Trip Time
2 % or 10 mA for Ι
Nom
= 1 A, or 50 mA für Ι
Nom
= 5 A,
2 % class according to IEC 60255-8
3 % or 1 s for Ι/(k ·Ι
Nom
) > 1,25;
3 % class according to IEC 60255-8
Influencing Variables Referring to k · Ι
Nom
Power supply direct voltage in range 0.8 ≤ V
PS
/V
HN
≤ 1.15
PS
om
1 %
4.12
Technical Data
4.12 Thermal Overload Protection
SIPROTEC 4, 7SJ61, Manual 315
C53000-G1140-C210-6, Edition 05.2016
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