Three phase upgrade question

[canron]

Hello all...hope someone here can help....


currently have three phases coming in to the property (old farm) but only receive single phase with a single phase meter. The overhead cables were upgraded a few years ago so the cabling up to the meter is all fairly recent, I can see the 3x100amp fuses on the grids side of the meter, only one is used

the supplier is asking for 'maximun load reading for each phase' and 'maximum load in kVA expected for the site' which they say they need so they can determine what kind of upgrade is required.

I could total up all the lights/appliances for the site maximum but what do they want to know when asking 'maximum load reading for each phase'?

I thought it would just be a case of changing the meter...

 

[plugsandsparks]

further back there is a local transformer that has to have capacity for your upgrade

 

[snowhead]

What are you adding to need to have to upgrade to 3 phase?

As above the supplier has to establish whether the supply up to your house is able to cope with the new demand.

If you're adding a lot of extra load you could end up paying not only for a new local transformer but cabling back to the next one and a larger transformer there as well etc, etc.
The cost could be anything from a few pounds to tens of thousands of pounds.

You need to supply them with accurate figures with professional assistance.

 

[canron]

it's a woodworking machine with 2 motors - (looking at the plates) one is 4kVA, other is 1hp, so not much at all
maybe smaller sized machines in the future but only ever one operating at any time

surely the 3x100A that comes in just now is sufficient?

or am I missing something?

 

[The Ghost]

Well he is (missing something), a three phase meter and supply. Think you may have to be careful so you don't get penalty charges they are bringing in next April though and be accurate with your maximum demand figure in Kva.

 

[canron]

Looks like I'll have to get someone else in to be safe....

I asked an electrician, he said the only thing that matters is the max demand figure. Told him what it was for...he just said to put 60-70 kVA.

As I say I don't even know what they're looking for in the 'maximum load reading for each phase'...is this also an estimate or an actual reading with a clamp meter or similar?

 

[Toneyz]

Well he is (missing something), a three phase meter and supply. Think you may have to be careful so you don't get penalty charges they are bringing in next April though and be accurate with your maximum demand figure in Kva.

What penalty charges are they could you explain more please Vort.

 

[KEV 1 N]

A 3 phase supply needs to have a balanced load across the phases, if you do get a 3 phase supply your existing single phase DB would have to be changed to 3phase and the circuits split equally (or as best they can) across the phases. I've also heard that unbalanced loads are charged (electric bill) on the phase with the highest KWh for them all.
EG L1 - 4532 KWh L2 - 3674 L3 - 2236 you would pay the highest 4532 for all 3 phases

 

[snowhead]

surely the 3x100A that comes in just now is sufficient?

or am I missing something?

Your other 2 phases aren't currently in use.
They may have used up any spare capacity on those 2 phases somewhere else in the distribution network.

 

[marconi]

It may be more economic to stick with your single phase supply and use an inverter to power your woodworking machines. Plus, if you ever move you can take it with you.

eg: Frequency Inverter ST9100A 4KW 230V - https://www.sourcetronic.com/shop/en/frequency-inverter-st9100a-4kw-230v.html?gclid=EAIaIQobChMInrGh097N1gIVbL7tCh1NSQDpEAQYAyABEgLwYPD_BwE

You will need to take advice on what type of inverter to buy and how to install it safely.

 

[KEV 1 N]

A 3phase generator might be an option, may be cheaper if the supplier decides to charge a fortune to install supply

 

[canron]

I initially intended to go for a converter....before I saw the plates on the motors (I told them it was a 7.5 and 1kw motor) I was told I'd need a rotary converter as one of the motors is for a hydraulic pump which needs a lot of torque.....The model they recommended was about £1500...

So thought getting actual 3 phase (since the wiring is already there) might be a better option. Starting to doubt that now!

 

[KEV 1 N]

Someone I knew wanted 3 phase on his farm, although he had single phase, the overhead cables were literally passing on the road near by....supplier wanted 10grand to install 3 phase and that was several, maybe more years ago!
He has a diesel generator and runs it on cherry!

 

[canron]

For one machine a genny might be a bit much...the machine would only operate for 5-10 mins at a time, sometimes could go a few weeks without using it but it's essential. Any 3phase gen I've seen are a fair few thousand...will have a look tho!

The supplier said about £300-400 to change the meter....if its going to be multiple thousands I'll definitely be leaving it!

As I say initially I thought the hydraulic pump motor was 7.5kw but turns out it's 4....so maybe don't need as big a converter as first thought

 

[The Ghost]

What penalty charges

Excess capacity penalties for half hourly electricity supplies - https://www.theenergydesk.co.uk/excess-capacity-penalties-half-hourly-electricity-supplies/ I did not know about these until @Leesparkykent mentioned penalty charges in a post I made recently. So a bit of research found the above. I think the giveaway is when they ask for the supply needs in Kva. However if you do get penalty charges you just re-negotiate your maximum supply demand.

 

[Leesparkykent]

That's only if the have half hourly billings and an authorised supply capacity though.

 

[canron]

How many different grades/capacities? Are there for 3x100amp coming in to the property?

I've seen 45kVA (seems low) and 70 kVA mentioned...are there others?

Also balancing the load...will they bill 3x the highest used phase?

 

[canron]

Your other 2 phases aren't currently in use.
They may have used up any spare capacity on those 2 phases somewhere else in the distribution network.

When you say not in use do you mean no load on them. Or might they not even be connected?

 

[Percyprod]

As a dno employee, it sounds as if you just need a straight forward meter change. You're load is well within the 100 amp supply. Just put the estimated load per phase. Don't worry about changing the existing customers, only needed if you have a high load on one phase creating problems. So 50 amps P1, 20 p2 , 10 p3 is not a problem. Half hour metering only applies to large power, where the MD ( maximum demand) is measured every half hour, if it goes over the agreed MD you pay extra.

 

[Megawatt]

Looks like I'll have to get someone else in to be safe....

I asked an electrician, he said the only thing that matters is the max demand figure. Told him what it was for...he just said to put 60-70 kVA.

As I say I don't even know what they're looking for in the 'maximum load reading for each phase'...is this also an estimate or an actual reading with a clamp meter or similar?

It’s basically a load sheet from the power company