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Figure. 5.3.19 - 158. Thermal response with k
SF
factor correctly set.
When the installation conditions vary from the presumptive conditions, the cable's current-carrying
capacity can be reduced so that the temperature of 90
̊
C is achieved with a 550 A current instead of
the 680 A current given in the initial data.
Estimating trip time
Calcula
Calculatted e
ed effffectiv
ective nominal curr
e nominal current:
ent:
I
N
=k
SF
× tamb
fact
× I
Nom
Where:
• I
N
= calculated effective nominal current
• k
SF
= the service factor
• k
amb
= the ambient temperature factor
• I
Nom
= the nominal current of the protected device
Calcula
Calculatted end hea
ed end heating:
ting:
A
AQ
Q-F213
-F213
Instruction manual
Version: 2.04
223