3 phase connection cost

[banjo]

how do you identify a 3 phase supply?

3 cables on the over head power lines?

both my neighbours were dairy farms and have 3 cable power lines to them, our supply comes across from one of the neighbours, a 3 cable supply leaves his place, where it used to go to a radar station up on the hill, our supply comes off this line, but our line is only 2 cables- off the top of my head I think they are connected to the two outer cables of the 3 cable over head. so the middle one just stops at a dead end.

then 6 poles over to us. not got much use for 3 phase, just interested really.

Four cables is three phase, three is normal like a plug.
Two positives cables in on three phase. Funny enough I was talking to my blacksmith about this yesterday. His machinary is all three phase, he has three phase just over the road 30m away and they wNted 20 grand to move it to him. He decided to run all his stuff of a three phase generator and it works really well. And has done it for years.
He also talked about the gizmos that turn single phase into three phase and said you have to be careful as a good unit costs a fortune. Not sure on this though.
He convinced me to go the generator route as I want a nice lathe.

 

[Iron150]

But im right in thinking its 3 wires on 3 phase on the overground wires?

QUOTE="banjo, post: 2224834, member: 17702"]Four cables is three phase, three is normal like a plug.
Two positives cables in on three phase. Funny enough I was talking to my blacksmith about this yesterday. His machinary is all three phase, he has three phase just over the road 30m away and they wNted 20 grand to move it to him. He decided to run all his stuff of a three phase generator and it works really well. And has done it for years.
He also talked about the gizmos that turn single phase into three phase and said you have to be careful as a good unit costs a fortune. Not sure on this though.
He convinced me to go the generator route as I want a nice lathe.[/QUOTE]

 

[roscoe erf]

Four cables is three phase, three is normal like a plug.
Two positives cables in on three phase. Funny enough I was talking to my blacksmith about this yesterday. His machinary is all three phase, he has three phase just over the road 30m away and they wNted 20 grand to move it to him. He decided to run all his stuff of a three phase generator and it works really well. And has done it for years.
He also talked about the gizmos that turn single phase into three phase and said you have to be careful as a good unit costs a fortune. Not sure on this though.
He convinced me to go the generator route as I want a nice lathe.

you also have 5 core three phase

 

[ridger]

Our last machine had 5 cores in cable, 3 live, neutral and earth possibly? I use an invertor, have had it 6 years with no problem, it's 40 horse though

 

[Pheasant Surprise]

Overhead wires:
High voltage (11kv and above): 3 wires as the currents are balanced across the phases, no need for a neutral.
Low voltage (415v, typical domestic or commercial supply up to 100 kVA): 4 wires either aerial or underground supply back to the local transformer.

Supply within premises: Typically 4 or 5 wire on the lead, depending on earthing arrangement with the connected appliance. 3-phase socket outlets should be a 5-wire connection back to the distribution board.

 

[Pheasant Surprise]

Inverters are fine, but they can still be quite expensive depending on size. This is due to the IGBT and SCR electronics within them. Typically they are use on a single appliance rather than for an entire premises.

 

[ridger]

Inverters are fine, but they can still be quite expensive depending on size. This is due to the IGBT and SCR electronics within them. Typically they are use on a single appliance rather than for an entire premises.

I run all my machines on mine, but I'm not exactly a massive operation, most I'd ever have on at once would be about 8 motors. I got mine out of a sawmill which was closing down, it cost 950 euros Probably because it was advertised as sold as seen, but I had seen it working before the place shut

 

[Iron150]

How many wires on 11kv 3 phase going under ground, our line goes obove ground apart from one piece going underground under neighbours garden, its got 3 wires going underground but only 2 seem to be used currently, would the three be sufficient for three phase or would they need to dig the garden?

QUOTE="Pheasant Surprise, post: 2225004, member: 1103"]Overhead wires:
High voltage (11kv and above): 3 wires as the currents are balanced across the phases, no need for a neutral.
Low voltage (415v, typical domestic or commercial supply up to 100 kVA): 4 wires either aerial or underground supply back to the local transformer.

Supply within premises: Typically 4 or 5 wire on the lead, depending on earthing arrangement with the connected appliance. 3-phase socket outlets should be a 5-wire connection back to the distribution board.[/QUOTE]

 

[Exfarmer]

i could be wrong but I believe they only charge you for electricity used across 2 phases so balancing your power usage across all 3 phases should save you a third of your electricity bill.

This is with Northern Ireland Electricity so could differ across the water

Sorry it does not work like that.
A 3kw motor will use 3kw if it is single or 3 phase.
However start up loads are far less and each cable is carrying less power so 3 phase enables you to run far more equipment on a given supply.
Distribution companies will be unhappy at you running too big a supply on single as you can give the network shock loads pulling down the voltage locally.

 

[Pheasant Surprise]

How many wires on 11kv 3 phase going under ground, our line goes obove ground apart from one piece going underground under neighbours garden, its got 3 wires going underground but only 2 seem to be used currently, would the three be sufficient for three phase or would they need to dig the garden?

Where is the transformer? Count the wires coming off it. Sounds like you may have a split-phase connection; 1-phase at 230v and the other at 460v.

Edit:
From experience, the lead-in cable will be the least of your worries. If you *really* need 3-phase then you will have to get in touch with your local supply (DNO) company unfortunately.

Even if there is a 3-phase LV supply that you can hook into, its not altogether as simple as that when upgrading from a single-phase supply. This is because the designer at the DNO will need to look at how much power you will draw out of the network and whether the local transformer will stand it.

In our case we had to chip in to upgrade the transformer, and pay a pro-rate cost. This could end up being a rather large sum of money.

 

[Iron150]

Transformer is my side of where it goes underground, one of the wire tgats going underground is not curently used, two wires on the overhead both sides of the garden, would it be three wires going underground for three phase before the transformer?

 

[Pheasant Surprise]

Transformer is my side of where it goes underground, one of the wire tgats going underground is not curently used, two wires on the overhead both sides of the garden, would it be three wires going underground for three phase before the transformer?

There will be 3-wires feeding the input side of the transformer. Here's UKPN swapping our local one over.

The three large ceramic insulated terminals are the 11kV 3-phase supply going in, L1, L2 and L3 (the primary is delta wired). On the reverse side of the transformer there are four smaller terminals, they are L1, L2, L3 and N (this secondary side is star-wired). In our situation the transformer is pole mounted, the 11kV supply coming in from overhead. The 400V 3-phase (and 230V single phase) supply comes down the pole and runs in an underground aluminium 4-cored armoured cable, with either full 3-phase takeoffs (4-wire) or single phase take-offs (2-wire) as required.

 

[CJay]

Sorry it does not work like that.
A 3kw motor will use 3kw if it is single or 3 phase.
However start up loads are far less and each cable is carrying less power so 3 phase enables you to run far more equipment on a given supply.
Distribution companies will be unhappy at you running too big a supply on single as you can give the network shock loads pulling down the voltage locally.

Not sure what your getting at, I was referring to the metering process only not power usage but I still could be wrong mind.

 

[Pheasant Surprise]

i could be wrong but I believe they only charge you for electricity used across 2 phases so balancing your power usage across all 3 phases should save you a third of your electricity bill.

This is with Northern Ireland Electricity so could differ across the water

If you've got a kosher three phase supply, you will have a three-phase meter (3 brown cables, 1 blue cable in and out) which measures current through each phase. They will charge you for each and every kWh that runs through that meter, irrespective of the phase its coming through.

If your supply is only 2 phases (i.e. a 230v and 460v split-phase supply) then it stands to reason that you will only be metered for those two phases.

Maybe that's where the confusion lies?

 

[CJay]

If you've got a kosher three phase supply, you will have a three-phase meter (3 brown cables, 1 blue cable in and out) which measures current through each phase. They will charge you for each and every kWh that runs through that meter, irrespective of the phase its coming through.

If your supply is only 2 phases (i.e. a 230v and 460v split-phase supply) then it stands to reason that you will only be metered for those two phases.

Maybe that's where the confusion lies?

That sounds right ! The old story if it doesn't sound right it's probably not applies to what I've been told I would say.

 

[watfordfrosty]

when we enquired western power wanted 20K just for the transformer for a three phase supply

 

[Pheasant Surprise]

when we enquired western power wanted 20K just for the transformer for a three phase supply

New transformer or upgrade existing?

 

[defender]

If your supply is only 2 phases (i.e. a 230v and 460v split-phase supply) then it stands to reason that you will only be metered for those two phases.

all phase voltage is 230/240 the 460/480 is got by measuring voltage line to line
same as 3 phase ,phase voltage is all 230/240

 

[Pheasant Surprise]

all phase voltage is 230/240 the 460/480 is got by measuring voltage line to line
same as 3 phase ,phase voltage is all 230/240

Yes. Phases are 180 degrees parts for split-phase hence higher line-line voltage (230 + 230) than three-phase where the phases are 120 degrees (230 x sqrt of 3.) apart.

 

[watfordfrosty]

new transformer