3-phase cable calculation

[HomeCert ltd]

Hi,

A while ago I posted about my neighbours 3-phase generator etc....

So he's being running through diesel like there's no tomorrow and been talking to a local barn who have said he can take the power from his property to supply their kiln.

He's been measuring the his average usage over the last month or so, an on average his kiln uses 12kw, so we will run a cable for a 15mw supply to side on caution.

So he wants to bury a 3-phase supply to the kiln from the barn. The barn is roughly 1000m away. I wanted to check to see if I'm calculating the cable size correctly.

15kw/400 x 1.73 = 64.9amps

So Woud that be 21.6amps Per phase?
I'm struggling to work out volt drop to determine the CSA of the cable?

Thanks

 

[Darkwood]

The kiln has small electrical draw. There 400v fans which circulate the heat, the source of file is chipping a from a small hydronic shaft. When I measured it, everything was set to maximum demand, so the desired temp was set above max output so would have thought that would have been the highest demand even with the shaft in operation

Don't get me wrong here, I'm not trying to trip you up, I never like the term 'I thought' 'I assume' 'I guess' when members are giving what is vital info in order for us to respond, like I said, how do you know you don't have a bank of elements down, the balance of the current demand would suggest not but there exists ways to connect the elements that would still leave a balanced load if an element failed.

You need to know how many elements are in the kiln, the wattage of them and the voltage, plus how they are connected, the uncertainty you have about the info supplied means you will have to work it out yourself.

 

[HandySparks]

...the source of file is chipping a from a small hydronic shaft...

Can you explain further please?

 

[HomeCert ltd]

there is no elements in the kiln, the kiln is formed from 2 containers. One houses the fuse board, a large furnace with a storage area with wood chipping. The furnace burns 24/7, and there's a small shaft which basically pushed chippings every so often into the furnace to keep it burning. Then the heat from the furnace travels through a duct powered by 2 fans into the secondary container unit, which is used to store logs which are dried out.

 

[Darkwood]

Ok more info now which creates more questions, what are the ratings of the 2 motors?

I assume you mean an Auger when you say shaft (like an helter-skelter inside a tube) when it turn it pulls the fuel through, this will also have motors on it but tend to be small in my experience.

Motors been inductive loads with inrush to start up will need you to make sure VD is correct.

 

[PEG]

Hi,is this a pellet/chip processor?
If so,it's power needs would be different to an actual "kiln"

 

[LeeH]

Surely the civil works costs alone would make this project a non starter!

That’s one long run you have there.

 

[David M]

Hi,

A while ago I posted about my neighbours 3-phase generator etc....

So he's being running through diesel like there's no tomorrow and been talking to a local barn who have said he can take the power from his property to supply their kiln.

He's been measuring the his average usage over the last month or so, an on average his kiln uses 12kw, so we will run a cable for a 15mw supply to side on caution.

So he wants to bury a 3-phase supply to the kiln from the barn. The barn is roughly 1000m away. I wanted to check to see if I'm calculating the cable size correctly.

15kw/400 x 1.73 = 64.9amps

So Woud that be 21.6amps Per phase?
I'm struggling to work out volt drop to determine the CSA of the cable?

Thanks

Are you sure the barn is 1000mtrs away, not 100mtrs?
If the barn is 1000mtrs then for the 15kw supply you would require a minimum 70mm2 cable. But this gives you the bare minimum supply voltage so more information is required to do an accurate calc. Once other things are factored in i.e routing of cable, type of load, power factor of load...you are probably looking at more like 95mm2 as Lee stated. @ around £30 x 1000mtrs = £30k just for the cable! This is about the same cost as 6500 gallons of red diesel.

 

[buzzlightyear]

95mm at £31 per meter, x 1000m is £31k for cable. Might be cheaper to contact U.K. Power networks for their own supply.

or hop for one of them!