Hi everyone, I would liketo know if there is any formula which I can use for the breaker and overload of a motor starter selection based on the motor´s hp´s or power, how can I select the right protections?????

Best regards

Hugo

 

One would also need to know the voltage.

 

The voltage would be 480V......

 

I=P/E as simple as that!

Start-up current may be as much as six times run current.

 

and start up currents fall quickly..
so a delay relay should probably help

 

Chances are pretty good that your calculation will fall between the available fuse size (eg 4.5 amps) . You'll need to go to the higher size and probably a time delay or slo-blo fuse. A time delay will allow the higher startup current
to pass for a short time, but will blow if the current remains high..

 

What about the overload relay?? Is there any specific rule??

 

Different rules for different classes. Which class do you require?