Sizing Disconnect/Breaker for main feed
Sizing Disconnect/Breaker for main feed
(OP)
This may be a remedial question, but I can never seem to find exactly what I am looking for in the NEC.
I have a control panel that has the main 480VAC power feed into a breaker - (ABB Tmax) Power then branches into three motors and a transformer. Each motor and transformer is protected per NEC and manufacturer recomendations. I am trying to find how to size the main breaker. Is there a rule of thumb or a very specific formula/table? I am trying to master the process, not just answer this one situation.
Thanks in advance.
I have a control panel that has the main 480VAC power feed into a breaker - (ABB Tmax) Power then branches into three motors and a transformer. Each motor and transformer is protected per NEC and manufacturer recomendations. I am trying to find how to size the main breaker. Is there a rule of thumb or a very specific formula/table? I am trying to master the process, not just answer this one situation.
Thanks in advance.
"To be or not to be, that is the question" - William Shakespeare via Hamlet





RE: Sizing Disconnect/Breaker for main feed
Post back if you have questions.
Cheers,
dpc
RE: Sizing Disconnect/Breaker for main feed
But then you would also have to consider the maximum current each motor can draw when there is a voltage sag of about 10%
You might also have to consider the diversity factor of your loads