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 up to 125 A under difficult thermal conditions, the maximum rated continuous operational current must be limited as a function of the ambient temperature:
Limitation of the rated continuous operational current in combination with accessories
The table below shows the maximum rated continuous operational current for the plug-in version of switch disconnectors in sizes 160 A and 250 A and for switch disconnectors combined with residual current devices:
None of the other available accessories require derating of the 3VA1 switch disconnector.