Electrical cable sizing?

Question

What size cable would one need to supply 400 amperes, 380v 3phase 60 Hz at a distance of 1000 metres? Or is it better to go to transformers and high voltage. All power is by way of gensets. Right now we have numerous gensets on this farm. All are critical power scenarios. Any advice is very welcome. Cheers.

Answer 1

I used this online voltage drop calculator:
http://www.monachos.gr/en/calculators/voltage_drop.asp

For 500mm^2 wire it calculated 6.5% voltage drop if the load power factor is 1.0, 11.4% for 0.9 pf and 12.9% for 0.8pf. I don't know if that is for wire in magnetic conduit, or if that makes a lot of difference.

The information I have found that the inductive impedance of the wire is more than the resistance.

Answer 2

i would go hi voltage. do a calculation to see if its best. power loss is ( i squared)(r). your i is big; its 400 freaking amps. 400 squared is 160000. you have to look up r for your cable im sure its all over the internet just google 'resistance of power cable'. you will get resistance for different diameters. pick a diameter that you want to use and multiply by a thousand meters and you have resistance in ohms. now multiply this resistance by 160000 and you now have the watts lost. try the biggest diameter cable that you are willing to buy to reduce wattage loss. if the loss is unacceptable go hi voltage to cut i-squared-times-r power loss. if you have to generate twice the power just to compenste for power loss, then go hi voltage. be safe.
i found a web page that shows copper wire of 4/0 to be .16 ohms per thousand meters of length. so using this cable you would lose 160000x 0.16= 25,600 watts and the cable would probably be red hot and catch on fire and burn up its sheathing. thats over 25 kilowatts of just loss. the loss will be higer for an ac transmission. 4/0 cable is half inch diameter cable. i dont see how you can do it with low voltage/ hi current. you could try using a lot of cables. if you 100 half inch diameter cables to spread out the heat loss, first thats expensive. someone will want to steall all that cooper. and its still pretty hot. each one of these cables will be losing 256 watts which is as hot as 3 hudred watt light bulbs simultaneous. you have to go high voltage/low current and get your current down under an amp. you gotta buy a transformer for each end of the transmission. one to kick voltage up before going into the line and anothe to bring voltage back down at the end of the line. you will need a professional electrician for safety so that nothing catches afire and nobody is electrocuted. dont do it yourself.

Answer 3

relies upon the place you reside.., i assume its uk... wherein case. 240V at 9 kVA provides 37.5A it particularly is barely in basic terms over the score for 6mm cable it particularly is burried in the plaster on the wall, at 3.5m run which would be advantageous provided there is not the rest linked, ever!, to that end the spur wiring. your electrician is nice in that the secure practices (fuse) will avert possibility via blowing first yet once you pick 10mm cable you get 10mm cable, its in basic terms a short run, and if its what you pick and dont strategies the fee/disruption then decide for it. There are greater elecricians, yet you have in basic terms one million peace of strategies.

Answer 4

single conductor 75F ampacity for 400 amp is 250 MCM. with that size needs underground routing. if you wish to install it using overhead wiring on a poles, you need transformer to lower the transmission line current.

the voltage drop question, use the following equation:
V = 21.4 * L * I / CM
V= voltage drop in volts
L= one way lenght in ft (1000m=3280ft)
I= current in amp (I=400)
CM= conductor size in cir mil (250MCM=250,000 CM)

tremendous voltage drop, this is more of the reason you need a transformer to lower the current

Answer 5

With the price of cable rising, transformers
will save you some dough if the payback
time is there.
At 1000 M. they'll save you energy as well.