Siemens 3VA1 100 A Manual page 494

Technical specifications
6.4 Derating and temperature compensation
Example 2: Calculation of the tripping time
Starting point:
Based on the example above, the tripping time for an overcurrent I
calculated.
To compensate for the ambient temperature of 60 °C, rather than 50 °C, the thermal trip unit
has been set I
The first step is to calculate the ratio between the overcurrent and the system current:
I /I = 360 A / 90 A = 4
o
Using this value, it is now possible to read the tripping time from the characteristics chart:
①
494
= 95 A for a system current I = 90 A.
r(60 °C)
Tripping time (schematic representation)
= 360 A will now be
O
3VA molded case circuit breakers
Manual, 04/2015, A5E03603177010-02