Trip Curve

Status
Not open for further replies.

ceb58

Senior Member
Location
Raeford, NC
While driving a long way home this afternoon, I got to thinking. Dangerous thing. This is an off the wall question but, given a regular breaker nothing special as 100% rated or any thing. Is there a "rule of thumb" for calculating a breaker size just by the LRA of a motor.
What got me thinking was a name plate rating I was reading. It had FRA of 25 with LRA of 102. The motor was on a 30amp breaker. Which has me wondering about the ability of a breakers size in relation to the inrush of a motor starting. In this case the 30amp breaker is able to handle a little over 300% of its rating even though I know that on start up the motor would probably not reach its rated LRA rating. Or am I just driving too much?:D
 
Strictly speaking in generalities.

Most molded case circuit breakers (<100A) can carry 10x their handle rating for a brief instant before their 'magnetic' trip functions.

Please do not use this as an actually sizing 'rule of thumb'.
 
Status
Not open for further replies.
Top