Distribution From a Substation

Find a qualified electrical engineer, explain your problems to him. If he understands then hire him.

An architect or structural engineer will design the building to suit the cable exit routs and internal layout.

Why would you put the substations at the 4 corners, not cost effective at all.

If I were doing this project I would install overhead distribution lines. It is much simpler. Since this is for residential customers you would layout the line as if it were a subdivision with pole mtd transformers serving 4 houses. You would install feeders from each sub having a tie point so you could feed the load from the other subs.

An underground distribution system is more complex requiring more pad mtd switches, possible cable failures and much more costly. Overhead is the way to go. If you need help I can be on the next fight.

Sorry wareagle, but why make a new development look like a 1940's shantytown. OH is unsightly. From the OP all other utilities will be UG, why spoil our side of it?

TonyS

Just my opinion. First the OP is trying to provide service to what appears to be a large complex at 415 volts. Problem in the making. If he wants to go UG he should use a 15 kv system with pad mtd transformers.

Why don't you use 10Kv./60 Amps cables towards 10kv/415V outdoor transformers to the clusters of houses.

From there you break it down with some more handy 415 volt cabling ?

You even can lay a ring of 10 Kv to be able to feed from any side.

L8rz.. T L.

Detailed engineering has to be done.Please engage good consultant to do this type of assignment.

You may think of feeder pillar boxes at convenient locations for distribution of power to individual houses.

Thanks for showing interest in this thread

I would like to clarify a few things here to make the things a bit clearer.

Each substation has two 1600 kva 11/0.515kv transformers. From its MV panels, about 30 cables of sizes varying from 185 to 400 sq mm will be going out to the feeder pillars. Out of these feeder pillars smaller cables of say 35 sq mm will feed individual houses (a cluster of say 5 houses) The distance between the substation and the feeder pillar varies from 100 to 150 m. so we have to use bigger size cables. Also the load in gulf is more due to the extensive usage of ac.

Having the over head system is simply not allowed in this area. It has to be underground.

The length of the cable is more because of the turns along the existing houses. We can't take it under the proposed houses. The route has to be along the road.

11kv would of course be a ring main and will be dealt by the government department. Our scope of work is from 415v MV panel onwards.

Now my question is

When I take these cables out of the substation, through some sleeves out of its concrete walls, how can I arrange these cables to minimize the space occupied? Can I put them one over the other with some spacing? If yes then how much should be the spacing?

Secondly, I want to know the minimum clearances needed between cable to cable, from cable to water pipes , cable to elv telephone etc.

And lastly I want to know why the design drawings show two 185 sq mm cables to certain feeder pillars when we can use a single 400 sq mm cable more conveniently.Any special reasons?

If you have any source from where I can get all this info, or have any practical experience in gulf, pl do help me.

Thanks again.

First of all I actually build a few villages in Riyadh, Djeddah etc, even one near Basrah

I worked also on the Bahrein Causeway, also a few sites not to mention on this board.

I usec to live there, so I know the conditions VERY well.

For the troughput trough the walls you can use MCT's from the offshore branche, MCT= Multi Cable Transit , you can have and make them ANY size you want, just look into an Internet brochure from some Offshore E&I supplier, (QS Recommended Vendor)

For the normal 5corex185 You don't have to do much on spacing as they all are the same 415 voltage rating, just lay them next to each other and nicely on top of each other as on a cabletray, just remind the minimum 60 cm. Only 2 layers are allowed.

The single 400 sqmm cores you have to cleat , which means you have to put holders ( cleats) every 30 to 50 cm around the three phases ( on short circuit the loose single cores would fly out of the trench)

Personally I'd go for the depth of the trench for the 400 sqmm on 90 CM

A cleat is a 3 core holder from the Offshore world. (same brochures )

I cannot give you names for companies, some others might sue me for advertising

Questions, you can send me an internal CR4 mail

ciao L8rz.. T L.

Thanks a lot for your answer. It's great to have someone who knows the conditions that well. But there are a few things which remained unanswered first is the reason why to use 2 four core 185 sq mm cables instead of one 4c 400 sq cable. I guess not only would the latter reduce the number of cables coming out of the substation but also it would reduce the labour of pulling two cables and lugs glands etc on two cables.

Secondly I want to know the spacing between various utilities like water and telephone and which one should be above the other. I mean the order of putting the pipes and ducts for various services .

Lastly I want to know how wide the trench should be for laying about 30 cables approx… (of sizes 4 core 185 to 4core 400 sq mm ). Depth you have already mentioned minimum 60 cm and preferably 90 cm. but will that hinder with other utilities? I mean the clearance?

Also if you could mail me a list of suppliers dealing in mct or other related products to be used while cable distribution.

My mail id is vivek_1406@yahoo.co.in that is vivek underscore 1406

Thanks a lot again for your useful comments.

If you send the layout of houses,streets,path of other services and locations of substation we can easily suggest some solution

Without any scope or specifics I can merely guess

Maybe they have some leftovers from other sites?

The dept of 90 cm is specific for the single core, when shorted and not held in place properly it even would come out of the ground.

size of the trenches, you know the diameters of the cables ?

spacing with other utilities are supposed to be in the Scope of Works

For clashing with other utilities you need the dwg's of the other construction parties.

I told you I cannot advertise any recommended vendors from Offshore.

You shouldn't put a full email addy in these forums (read CR4 faq.)

Further , you are supposed to engineer this, not me , you get paid for it, I don't

We all don't mind to help or assist , there are limits.

Ciao l8rz.. T L.

The best solution is to have ring circuits from each ss to feed few feeder pillars.