We have 3 3 phase 3 HP fan motors that are
continuous duty.
Can we use cord and plug and the breaker
to operate the motors? or do we have to
use a overload section on each motor?

Thanks,
Sparky_1

Most 3 phase motors do not have built in overload protection. You have to install an overload device in each conductor & this is usually done with a motor starter. See 430.32

As for using the cord & plug connection, that will require a horsepower rated receptacle and a horsepower rated cord cap.430.109(F)

Tom

Thanks for the information Tom