THE DUKE

Can anybody advice on cable size for 250Kw star delta motor, star delta starter supplied with 240mm 4 core SWA protected by 500a fuses. Would like to keep cables at 240mm but terminal box looks a bit small for 2 x 240mm SWA cables motor is rated at 400v 430Amp

Regard

ps this is my first time on forum like what I see so far

Shakey

i am figuring on VERY rough calcs at about 360A per phase , which would make (again -off the top of my head calcs) cable size around 100mm

240mm looks like someone has been VERY generous

have you done any calcs for this?

wattsup

mm, you need a splitter box beneath the incomer

no such thing as 100mm, its 240mm or maybe 95mm, or perhaps 175mm?

give me the motor output in hp , the running current and start details, i will give you cable size and protection fuses

Spudmiester

Again with VERY rough calcs and no information on de-rating factors I recon on 120mm 3core x2 and separate earth to give you more room in terminal box.

benji

250kw star delta why not ditch the starter and get a soft start unit you'll save money in the long term
yours benji

daisy

I like benji,s idea. Anyway a common way of calculating the cable size is to realize the current in the cables between starter and motor when running is 0.58 times the supply current. But dont forget , as someone as already said the correction factors. If you are installing in conduit you already have one factor ,grouping. The six cables are loaded so in affect you have two curcuits. Best of luck.
Daisy
By the way did i say that is some motor?