Fuse Sizing

[Drewh24]

Hi I have been asked to size a few fuses up for some machines to protect against short circuit, i have been given the total kW which is 230 and its 3 phase 400V. What other information would i need? I Have had a quick guess at 450A put im not sure how to work it out.
any help welcome

thank you

 

[davesparks]

That's my calculation of design current based on your figures, assuming a PF of 1. But I'm just completing my Level 2 so I'm not saying this is correct.

Based on the information provided then yes you are correct, but the information Is somewhat lacking so overall your answer may not work out in the real world.

The PF is unlikely to be 1 on a machine of that size, but your guess is as good as anyone's until information is provided.

Likewise there may be efficiency to factor in to the calculation.