Starting current and breaker and cable choice

starting current going to last for few cycles,hence no need

to size the cable for the same.i would choose cable of size

considering In*1.2.

I would probably fuse it for 100 amp... possibly slow-blow... but I AM NOT A POWER PERSON!! I am curious how you high power types would do it?

Bill

Each jurisdiction, at least those with any sort of regulatory structure, will have a code in place that details what minimum and maximum ampacity those components must have.

For example... in general in Canada, motor feed conductors must be sized so that their ampacity is equal to or greater then 125% of the full load current of the motor.

You need to check with the Authority Having Jurisdiction where you live to get the requirements for minimum and maximum ampacity ratings for your location.

Hi, North of!

Tell me please, do you have different ampacity regulations concerning DOL starting smoke evacuation fans from generators, versus normal, delta-star starts for non emergency equipment?

Yes we do have separate regulations covering DOL vs part winding started motors.

What the regulations are in my area is not what you should be focused on. You should be focused on, IMHO, the regulations in your region.

For a given nominal current In = 57A, select as wire size (#4 awg)( 21 mm2) and for a circuit breaker 100A. Thus the multiplicator would be ~ 1.8. Normally 1.5 - 1.6. This is valid for normal motors under normal starting conditions. If the starting process extends over a longer period of time, the circuit breaker size shall be increased to avoid nuisance tripping during start. It would also be a good idea to verify the manufacturer's technical specifications.

Tomad