Which is the best suited line side protective device for following control transformer?
KVA rating - 7.5 kVA
Primary Voltage - 415 V AC
Secondary Voltage - 230 V AC
Construction of transformer - Toroidal core

Normally inrush current is 50 to 80 times for toroidal construction hence its recommended to add PTC in series to limit the inrush current as far as possible.
There is no suitable MPCB/MCB to take care of this high magnitude inrush current.