Thermal Overload Protection - Siemens SIPROTEC 4 Manual

4.13

Thermal Overload Protection

Setting ranges / increments
Factor k according to IEC 60255-8
Time constant τ
Current alarm element Ι
Extension with machine at rest kτ factor
Dropout time (emergency start) T
Trip Characteristic
Formula for primary values:
Trip Characteristic curve for Ι / (k ⋅ Ι
with
t Trip time in minutes
τ Heating-up time constant
th
Actual load current
Ιn
Preload current
Ι
pre
k Setting factor per IEC 60255-8
Nominal current for the protected object
Ι
Nom
Dropout Ratios
Θ/Θ
Trip
Θ/Θ
Alarm
Ι/Ι
Alarm
Tolerances
Referring to k · Ι
Referring to Trip Time
Influencing Variables Referring to k · Ι
Auxiliary DC voltage in range 0.8 ≤ V
Temperature in range –5 °C (23 °F) ≤ Θ
SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
th
for Ι
Alarm Nom
1 A
for Ι
Nom
5 A
Emergency
) ≤8
Nom
Drops out with Θ
approx. 0.99
approx. 0.97
Nom
Nom
/V
Aux AuxNom
amb
0.10 to 4.00
1.0 min to 999.9 min
= 0.10 A to 4.00 A
0.50 A to 20.00 A
=
1.0 to 10.0 relative to the time
constant for the machine
running
10 s to 15000 s
Alarm
2 % or 10 mA for Ι
Nom
2 % class according to IEC 60255-8
3 % or 1 s for Ι/(k ·Ι
Nom
3 % class according to IEC 60255-8
≤ 1,15
≤ 55 °C (131 °F)
Technical Data
4.13 Thermal Overload Protection
Increments 0.01
Increments 0.1 min
Increments 0.01 A
Increments 0.1
Increments 1 s
= 1 A, or 50 mA für Ι = 5 A,
Nom
) > 1,25;
1 %
0.5 %/10 K
393