TT Supply to Barn - LONG distance - help(?)

[s100cky]

Hi all,

Ive been to look at a project with a customer this evening. He is looking to put a 100A SPN supply into a remote barn location. He has had Western power out to look at the options, they have advised him they can pull a supply off a overhead line to give him a SPN 100A head.

The problem is that this is 415(ish) meters away from the Barn.

Now this isn't my usual bag, so sorry for the ignorance - and the books are not with me this evening, but I believe the options are as follows:

• Put a LV TT submain to the Barn, via a trench, which would be a massive cable due to VD.
• Get western power / others to install a HV radial from the overhead line to a small HV-LV transformer at the Barn. Reducing the size of cable and possibly the project cost?

Im sure I have overlooked some other options, but this one I cant get out of my head.

If anyone has done a project similar id be very interested to hear about it.

Regards all....

 

[ipf]

I've just been having a play with cable sizing for my own learning, (I've probably overlooked something massive) but I get you need a figure of 0.166mV/A/m or less for a 100A load over 415m - so according to the BRB that'll be 300mm cable - however, I'm happy to be shown the error of my working as I'm sure I've overlooked something to be taken in to consideration on larger runs like this.

Also, in table 4D4B (BRB) the columns split down to have an R, X, and Z column - but I can't find any notes on what this means. Can somebody enlighten me?

The z is impedance value, r is the resistive component and x the reactive. Have a look at correction for load power factor and how design value is obtained.

 

[hightower]

The z is impedance value, r is the resistive component and x the reactive. Have a look at correction for load power factor and how design value is obtained.

It might be a bit over my head for now, should imagine I'll cover it next year on level 3. Thanks

 

[davesparks]

It might be a bit over my head for now, should imagine I'll cover it next year on level 3. Thanks

Possibly not unfortunately, they certainly didn't bother when I was doing level 3!
To be honest it's one of those things I have never actually fully got to grips with