2 phase supply?

[Hotstuff]

Split phase is two phases, 180° out of phase with each other, sharing same neutral. 230V each, 460V between phases.

Not much use for anything as a supply over and above two single phases to increase capacity. Used to be able to get split phase motors iirc.

It's probably split phase, rather than two phases of a 3phase supply given its location I suspect.

This supply system is common in Hastings town centre.
Many years ago I was invited to our local ambulance station to quote for the installation of electrical supplies to serve their shiny new 3 phase vehicle lifts.
After checking out their distribution system I had to explain that there was a problem.

 

[Gareth J]

The dilemma that I believe my SiL has is that she can't get a smart meter so claiming export is difficult. And because its an oddball grid connection, she can't find an export meter that her supplier is willing to use for export monitoring. That was what I gleaned a couple of months ago in their local pub after a few beers so I'll refresh that info to make sure I've got the right angle of the dangle before sourcing or building anything. That and a chat with the solar installer should get me up to speed.

Had a new 3phase smart meter fitted to a split phase supply in March this year. It's currently monitoring import/export as it should. I queried the 3phase meter and it's appropriatness to use on split phase when it and the installer arrived and said, no issue, that's what should be fitted. Yet to get SEG payments but registration in progress.

Interested regarding monitoring etc, how do you use the data you get? I currently write down total generation of arrays on the wall next to the meters. Rather analogue

 

[brewdexta]

Interested regarding monitoring etc, how do you use the data you get? I currently write down total generation of arrays on the wall next to the meters. Rather analogue

I think my SiL wants some means of monitoring import/export and to help get some export payments but I need to have a longer chat with her.

I fitted my solar myself under G98 and had a spark look it over and do the final connections. So no MCS and no export payments for me but I don't care, I'm trying to export as little as possible. I use the stats so I can see the benefit of the system and check it working. The inverter cloud site gives some lovely stats but there's no guarantee that the history will be there. They recently updated the cloud portal and wiped all the previous data so doing it myself helps me ensure I have long term stats.

I have two data sources. The current sensors on the output of the solar and the main incomer, plus I have a detector on the smart meter LED, it flashes for every 100Wh if I remember correctly.

There is a way of talking to my Sofar Inverter via MQTT and get all sorts of data about battery charging and general system performance and health but I need to get the soldering iron out and build the interface, I've got all the bits but its looking like a retirement project.

 

[brewdexta]

Maybe get onto the electric board and see if they can convince them to change their supply to three phase

They should have done that before fitting the inverters, without getting more details on what is installed, it may mean them buying something different.

 

[Matrixx]

Small world, I used to live just outside of Lealholm, nice place if you like sheep.


I assume by split phase you mean 2 phases form a centre tapped transformer, common in europe etc. how would you know its vector relationship from that?

You wont get 460V AC as a supply in the UK (400/231) as it is not a standard voltage, and most switchgear in not rated for it (up to AC3), a 3phase meter would still work, as most sites dont have a balanced three phase loads.

 

[brewdexta]

I'm still investigating to find out what supply they actually have, 2 phase or split phase. Its a 3 hour drive over so trying to get the SiL to provide more info via pics and get the number of their solar installer. There's no rush, I'll be going over nearer to Christmas as my mum lives there too.

 

[Seadog]

I assume by split phase you mean 2 phases form a centre tapped transformer, common in europe etc. how would you know its vector relationship from that?

Because, being a transformer, it cannot be anything other than 180°.

 

[Matrixx]

Because, being a transformer, it cannot be anything other than 180°.

In a three phase transfomer they are 120° apart, so if you have 2 phases they will be 120 apart?(360/3) , as the source supply is not know I was confused as to where the 180 came from.

 

[Seadog]

In a three phase transfomer they are 120° apart, so if you have 2 phases they will be 120 apart?(360/3) , as the source supply is not know I was confused as to where the 180 came from.

Look at the diagram above.

 

[m_c]

In a three phase transfomer they are 120° apart, so if you have 2 phases they will be 120 apart?(360/3) , as the source supply is not know I was confused as to where the 180 came from.

It's all relevant to each other.
The conventional 3 phases are 120deg apart in relation to each other, but if you only take two of those phases, you get a single sin wave.
If you then connect a centre tapped transformer to any of those two phases/single sin wave, you'd get two sin waves 180deg apart around the centre tapped neutral.

Essentially old split/two phase systems were used to save the electric companies installation costs, as they only need to run 2 (typically 11kv) wires to the property, and the 240/480V setup gave more power than just basic 240V.

 

[Matrixx]

If unknown it could be anything.

Why would you want two single "out of phase" supplies at the same property it seems very dangerous.

I guess its a very old system, the installs I have done over the years have always been new equipement.

 

[Gareth J]

If unknown it could be anything.

Why would you want two single "out of phase" supplies at the same property it seems very dangerous.

I guess its a very old system, the installs I have done over the years have always been new equipement.

Because it allows more power consumption on site than standard single phase with less investment required than full 3 phase. Clearly used to be deemed a worthwhile trade off, even if it no longer is!

 

[Erie Fred]

If unknown it could be anything.

Why would you want two single "out of phase" supplies at the same property it seems very dangerous.

I guess its a very old system, the installs I have done over the years have always been new equipement.

The way it was explained to me, it's for safety, most times, you'll get 120 vac shock to ground.
To get a 240 vac shock would require to get across both hots (and they must be out of phase), much less chance of that.

 

[mtt.tr]

If unknown it could be anything.

Why would you want two single "out of phase" supplies at the same property it seems very dangerous.

I guess its a very old system, the installs I have done over the years have always been new equipement.

Cost.

You don't need to pull a third 11kv line in.

2 separate phases 120° apart are of limited use unless you want two single phase supplies. No good for an induction motor if you consider the sinewave 0 120 240 rather you would have 0 120 if that makes sense?

Where as 2 phases at 180° apart gives 460v or essentially single phase lots of poke less cable or two single phase supplies using the centre tap to get your 230v. Induction motors still require a start capacitor.

Old hat now but at the time materials were scares and valuable.

 

[mtt.tr]

The way it was explained to me, it's for safety, most times, you'll get 120 vac shock to ground.
To get a 240 vac shock would require to get across both hots (and they must be out of phase), much less chance of that.

Our supply is 230v not 120v like yours.

Though 120v will still kill you happily, we have 110v site power but centre tapped max voltage to earth is 55v. Obviously across lines you still can get a 110v shock.

 

[Matrixx]

Cost.

You don't need to pull a third 11kv line in.

2 separate phases 120° apart are of limited use unless you want two single phase supplies. No good for an induction motor if you consider the sinewave 0 120 240 rather you would have 0 120 if that makes sense?

Where as 2 phases at 180° apart gives 460v or essentially single phase lots of poke less cable or two single phase supplies using the centre tap to get your 230v. Induction motors still require a start capacitor.

Old hat now but at the time materials were scares and valuable.

The vectors only affect the amplitude, you could run the centre tapped of a single phase, but I guess as it is a remote site the supply will be TT, so the neutral would be the earth, so phase to neutral on a pole TX would not be so straight forward.

 

[Jack Ryan]

In Australia, remote properties are serviced by SWER (Single Wire Earth Return) lines. These are single phase 11kV supplies that feed a transformer on the pole at the property. The output of the transformer is, in this case, 480V with a centre tap. The centre tap is called "neutral" and the two hots form a split phase 240V supply with respect to neutral.

This is analogous to the American split phase system except that the Americans use 120V. Just like the Americans use the two hots to gain a 240V supply for heavier equipment, the two 240V hots can be used as a single phase 480V supply. The equipment obviously has to be able to handle that voltage.

It is not possible to use a second or third phase without running one or two additional wires over a very long distance.

I expect your (British) remote supplies are (were) similar even though your "remote" is slightly less remote than ours.

Jack

 

[mtt.tr]

The vectors only affect the amplitude, you could run the centre tapped of a single phase, but I guess as it is a remote site the supply will be TT, so the neutral would be the earth, so phase to neutral on a pole TX would not be so straight forward.

I'm saying drop a phase, at a certain point the phases are at the same potential. No good for running motors

This was in an era that vastly predates our norms.

 

[sparkysy]

I would imagine that it is split phase which is still around in remote areas and some villages in the UK it is getting less as network improvement tends to sort it out!
It was a left over from times of old when there were not enough wires on poles for proper 3phase supply but high current equipment was needed to be used e.g. mills dryers and milking parlors.
I work on a couple of farms in the Midlands that are still using split phase feed mills every week, they were very well built and apart from replacing the main starter panel on one of them last year due to other idiots thinking they could fix it have been very reliable. Parts are becoming very difficult to source for these nowadays, the panel had to be bespoke built.
Most split phase around here now is as someone mentioned previously mainly used as two single phase supplies, which can be very useful at times!
Sy