Technical specifications
6.4 Derating and temperature compensation
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
639
Derating for the 3VA1 switch disconnector
The 3VA1 SD switch disconnectors do not have a trip unit. The temperature inside the switch
disconnector is however influenced by the ambient temperature and the current-dependent
power loss generated inside the unit. Nonetheless, 3VA1 switch disconnectors up to 125 A
do not require derating up to 70 °C.
To prevent overloading of switch disconnectors over 125 A under difficult thermal conditions,
the maximum rated continuous operational current must be limited as a function of the
ambient temperature:
No derating up to the rated operational current I
n
of the switch disconnector
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