cable sizes

[bugsy]

With a design current of 50kw how do you get 24a?

 

[pushrod]

Have a look at page 123 temp at 30C has no affect so can be disregard it in this case (table 6A) the other circuit derates it though-look at top line of table 6C (p126) . You will need to divide your current by 0.8

tricky question this one

 

[james king]

some1 help bugsy how did you work it out and what amps per phase do u get? im confused about the incoming tails say they are in 25mm per phase in to the board would u then come from the DB to the switch panel if so what cable size would u use then? can u some how find a diagram of it please mate

 

[bugsy]

could you please demonstrate the calculation

 

[james king]

lol some one demonstate the bloody calc thats all i ever wanted lol

 

[pushrod]

With a design current of 50kw how do you get 24a?

50 kW is a total power according to OP - so 16.67kW per phase then calc Il with formula given in post 25.

 

[pushrod]

16700W/( √3 x 400v) =24.1A

 

[pushrod]

You still hanging in there?

forgot to say √3 is 1.732

 

[james king]

im still watching lol i will top of the class if i get this with all your help lol

 

[james king]

so pushrod what is your cable size chioce?

 

[bugsy]

**** went to the wrong college

 

[james king]

so 70mm is way to big then if each phase only needs to caryy 24amps????????

 

[pushrod]

back to page 123 of osg and read post 32 again to calc It

no point telling you the answer if you can't explain it

 

[james king]

hehe just tell me ok il go get it

 

[pushrod]

so 70mm is way to big then if each phase only needs to caryy 24amps????????

way too big, but not there quite yet