Long distance cabling & 1Ph –> 3Ph

Hello, we operate in a remote part of East Malaysia. Our factory operates a 1.6MW steam turbine and fallback to diesel generator when required.

We have several domestic housing estates within a 10KM radius from the factory. These estate consume pure single phase loads. Lights, fans, tv, mobile phone. Very basic living. Currently, the loads are supported by diesel generator.

We are considering eliminating the remote diesel generator to save costs. One of these estates is 6KM away and the load is 7KVA all single phase. Approx 30amps if using 230volts.

Is there any issue with sizing a simple 2 core cable (proposed 2 * 35mm2 aluminium cores) and running it underground (steel tape armoured) from factory to remote estate; at factory, have a step up transformer (to 1000volts) that can convert the 1 phase load and balance it across 3 phases for supply side; and lastly a single phase step down transformer at remote estate?

Or it is only advisable to run a 3 phase cable between the 2 sites and then distribute the loads as best possible between different houses. The cost of running 2 cores single phase is of course cheaper.

If the cable is direct buried 1 foot below the ground, is there any recommend material for backfill?

Really appreciate any help.

Prashant Patel

going three phase could mean the use of smaller wire providing the loads at each site could be spit up. A 7kva load on 1.6 mW power plant is hardly nothing. I'm not familiar what type of Electical code and standards that are prevalent in your neck of the woods, however they would help determine sizing the wire appopiately and could be safely buried.

Typically buried cable costs more by the meter however it could provide better protection over a pole line exposed to weather, vegetation, what have you.

In the U.S., for those distances, a 1200 volt line ought to sufficient providing. However, cost of materials, availability of materials, knowledgible work force, terrain, etc will affect the over all cost so it may be prudent to run the numbers on various options if you gave good working data to work from.

You may also be better off working with someone who knows the ins and outs there in your area. Much more data would be needed to pin down wire size and type