Sizing of circuit breakers

[rvirgo]

I am trying to size a circuit breaker that has different current requirements based on the input voltage. The input can be 115VAC or 230VAC.The input feeds into a Frequency Converter that has a 400Hz output and a 60Hz output. The electronic rack we are building has 3 different configurations. If the input voltage is 115VAC then the input current for one of the configurations would be 12.6A. For the same configuration if I connect 230VAC to the input the current will be only 6.3A.

My question is: If I size the Circuit Breaker for 125% of the 12.6A. then when the customer connects up 230VAC the Circuit Breaker will at 250% of rating.

This doesn't seem right. Thus, I am leaning towards telling the customer of this problem.

Am I missing something?

Thanks,

 

[kingpb]

use 20A breaker and #12 wire. The lower current doesn't matter as long as the breaker protects the wire. Protection of the downstream device is another issue.

 

[Jraef]

Are you in North America or is the product intended for the NA market? 120V is Line to Neutral so you only put the breaker on the Line, but 240V single phase here is Line to Line, you would need a 2 pole breaker for that.

When I've done OEM controls for portable equipment capable of two voltage levels like that, I have put in two separate OCPDs and a selector switch for the user. otherwise it's asking too much for someone to know all the issues in the field.