Not sure what you are asking, or your application.
By definition, an incomer is just that, an power feed to a switchboard, MCC, or simply an isolator (oops - slapped wrists, I meant to say disconnector or switch-disconnector) on a distribution board
It may typically be an ACB, MCCB, possibly having overcurrent and / or earth-fault protection or possibly just a manual switch disconnector (definition as IEC 60947-2)
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Regards -
Colin J Flatters
Consulting Engineer & Project Manager