selection of switchgear ratings

[pssdeepak]

Can anyone please explain how can i select contactor,olr/mpcb,acb for a particular load for DOL? What should be the maximum load on the switchgear? Should it be 100% or less?

 

[Darkwood]

match the switchgear with the full load current as a minimum spec or the nearest size up, i assume the isolator wont be used to energise the motor direct but via a contactor and overload with start/stop buttons, if there is any chance the isolator may be used to switch off power when machine is running then make sure the isolator is rated for switching inductive loads as most isolators have ratings given for switching resistive loads and will be lower if used on inductive.
The overload should be the full load current rating of the motor and a contactor that can carry said load.