Single phase power all thats avaiable for new workshop build

[robertl]

Hello Everyone, new to the forum and looking for some advice on a new workshop, i'll explain.
I am planning on building a metal / woodworking workshop (mainly aluminium and stainless steel) for boat work, refurbishment and boat building.
I am a marine engineer to trade and i am planning on starting my own business doing this in said shed.
Now to understand what i will need for this machinery wise, obviously welders, pillar drill, lathe, press brake, guillotine, grinders, table saw, band saw, and anything else you may think on from grinders to anything else with a maximum of 2 people working separate machines at any given time. mostly just be me on my own.
Now the problem is where the shed is going there is no 3 phase within a mile of it. I can get a single phase 100A supply easy enough but not sure how that will work. Basically just wondering if i will get away with a single phase 100A supply and if i end up with 415v 3 phase machines then i can get an RPC which you can get up to 30hp now, The only other issue there is the 30hp rotary converter is 100A so in theory if the RPC was working to capacity that would be all of the capacity on the network. but to be honest looking at the size of motors in the machines i am looking at 10hp seems to be the max. so even with 2 of them there would be still plenty of spare capacity. but im stilll not sure if it is the right way to go.
What are your thoughts on this? the 3 phase would be wildly costly 50k upwards to install so that's out, i could buy land and put the shed elsewhere if it cannot work going forward but i would like to know your thoughts on this.
The land the shed is planned to go on is ours so it will work out a lot cheaper to put it there, just the issue of supply.
Thanks in advance
Robert

 

[littlespark]

Have you spoken to your supplier or network?
If there’s single phase, I would reckon there’s 3 phase underground or on pole somewhere that’s sitting redundant.

 

[robertl]

Have you spoken to your supplier or network?
If there’s single phase, I would reckon there’s 3 phase underground or on pole somewhere that’s sitting redundant.

Hi
The 3 phase ends about a mile away from where this is, its in quite a remote area in Shetland and the poles there only carry 2 cables. about a mile further back there are 3 phases on the poles and they end at a transformer at a housing scheme.
So the supplier said to get a 3 phase supply installed would mean them adding a 3rd cable from there to my property and then a new 3 phase transformer etc.
So he reckoned when i spoke to him it would be more than 50k to do this.
Thanks
Robert

 

[R-fur]

I would go with the single phase supply. If you need three phase for certain machines you can get electronic speed controls that will drive a three phase motor from a single phase supply. I would keep clear of rotory convertors.

 

[Spoon]

How are you heating up this shed in winter?
You need a list of the equipment you will be using along with power consumption ratings for the items. This will give us a better idea.

 

[Lucien Nunes]

the 30hp rotary converter is 100A .....10hp seems to be the max. so even with 2 of them there would be still plenty of spare capacity.

30hp = 22.4kW mechanical power output. If the motor and converter were both 100% efficient and had unity power factor the line current at 230V would be 22400/230=97A. But they are not. In practice the running current of a 10hp single-phase motor is around 50A so the converter will need at least that. Starting is a different matter, direct-on-line starting can require up to 5x rated current for however long it takes to accelerate the load. Motor performance may also be reduced when running on a converter-derived supply.

If you really do have individual loads that heavy, the 100A supply would be very marginal. You would need to look at voltage drop - you don't want things cutting out every time you start one of the big machines. The biggest loads might be best retrofitted with separate inverter drives as R-fur mentions, with perhaps a smaller general 3-phase supply from a converter. You would get better machine motor performance with lower running current and much more flexibility in limiting the starting current.

 

[davesparks]

If this is a new business which you are intending to grow then it would be worth looking at the long term view. Is it better to make the investment now to get the supply you need for the future rather than trying to have the supply installed in a few years time?
Once the business is up and running the inconvenience of having the power installed later and the timescales involved in getting it done could be problematic.

If the business plan is good and viable then you should be able to get business finance to set it up properly.

 

[Dustydazzler]

As above

If this is a long term venture , pay the money now and get a 3 phase supply run in.

Think of it as a short term pain 'financially' for long term gain

 

[Midwest]

Have you enquired about financial help from the Shetland Islands Council, that they publicise?

 

[telectrix]

could always convert to steam power.

 

[Dustydazzler]

could always convert to steam power.

Or even pedal power

 

[Strima]

As it's the Shetlands what about renewable energy such as wind or solar?

 

[telectrix]

As it's the Shetlands what about renewable energy such as wind or solar?

or shetland ponies on a treadmill.

 

[robertl]

As above

If this is a long term venture , pay the money now and get a 3 phase supply run in.

Think of it as a short term pain 'financially' for long term gain

I would look into this but i have been informed this morning that it would be far more costly than i even expected, would need a full new overhead powerline system down to the location of the shed, so to be honest if going down that route i would be far cheaper building it somewhere else.

 

[robertl]

30hp = 22.4kW mechanical power output. If the motor and converter were both 100% efficient and had unity power factor the line current at 230V would be 22400/230=97A. But they are not. In practice the running current of a 10hp single-phase motor is around 50A so the converter will need at least that. Starting is a different matter, direct-on-line starting can require up to 5x rated current for however long it takes to accelerate the load. Motor performance may also be reduced when running on a converter-derived supply.

If you really do have individual loads that heavy, the 100A supply would be very marginal. You would need to look at voltage drop - you don't want things cutting out every time you start one of the big machines. The biggest loads might be best retrofitted with separate inverter drives as R-fur mentions, with perhaps a smaller general 3-phase supply from a converter. You would get better machine motor performance with lower running current and much more flexibility in limiting the starting current.

I have had a look at each of the machines i would probably need, the biggest motor on any one of them is 7.5kw, i can be 90% sure that i would be using only one of these at any one time and maybe an inverter welder at the same time running on the 240v side.
it is a 23kva supply they SSE guy i spoke with said and he reckoned it would be more than adequate for what i am using it for.
The other possible option i thought of was having 2 seperate 240v single phase supplies installed,
as far as inverters go, would you need one for each machine? to let you know i am planning for most of the gear to get 240v stuff, this can work with a lot of it. but lathe, press brake and guillotines are hard to come by in single phase so it would be them i would need the 3 phase for. so maybe seperate inverters and converters is the way to go.
Are the rotary ones just no good or why dont you reccomend them?
thanks

 

[James]

Have you considered a generator?
Either diesel or natural gas powered if it’s available at your location.

 

[Andrew Hunter]

How often would these larger loads be required?
Have you considered having an auto start generator fitted just for the 3 phase loads.
If you can get a second single phase supply to the property there should be no problem getting a 3 phase supply and why would you want 2 separate bills.

The re-newable energy option in that location could be a good resolution as you would also be getting some money back if feeding on to the network.

But that all being said all the options are costly so if it is a matter of not being able to justify the expenditure then building closer to a supply or even finding a suitable existing site might be the answer.

 

[DPG]

I think he said the 3 phase option was cost prohibitive due to distance from the nearest 3 phase pole.

 

[Andrew Hunter]

I think he said the 3 phase option was cost prohibitive due to distance from the nearest 3 phase pole.

Would a new secondary supply single phase not be coming from the same place as the three phase supply would need to come from?

 

[DPG]

I might have misunderstood, but I thought he probably had 2 phases available.

 

[Shoei]

Hello Everyone, new to the forum and looking for some advice on a new workshop,...[snip].... I can get a single phase 100A supply easy enough ...
Robert

SSEN specify 100A max for domestic but say 100, 200, 315, 400 and 630 amp for industrial/commercial. Does the single-phase supply have the capacity to be uprated to 200A if you signed-up as an industrial customer? Worth asking the question.

 

[robertl]

SSEN specify 100A max for domestic but say 100, 200, 315, 400 and 630 amp for industrial/commercial. Does the single-phase supply have the capacity to be uprated to 200A if you signed-up as an industrial customer? Worth asking the question.

Have just asked this very question, and the answer was to upgrade from 100A it would need to be a 3 phase supply.
The guy said that 100A was the max they could supply to any property on single phase.

 

[Pete999]

Have you considered a generator?
Either diesel or natural gas powered if it’s available at your location.

From the information you have supplied, sounds like a base load generator is the answer, may be should have considered your load requirements prior to planning the workshop project, whatever choice you take good luck.

 

[robertl]

How often would these larger loads be required?
Have you considered having an auto start generator fitted just for the 3 phase loads.
If you can get a second single phase supply to the property there should be no problem getting a 3 phase supply and why would you want 2 separate bills.

The re-newable energy option in that location could be a good resolution as you would also be getting some money back if feeding on to the network.

But that all being said all the options are costly so if it is a matter of not being able to justify the expenditure then building closer to a supply or even finding a suitable existing site might be the answer.

The larger loads would be infrequent use at best, and i have been thinking about it realistically. the only time that 2 of these things would be running at the same time would be lets say a press brake and guillotine running at the same time.
Now you would be alternating the use, i.e when bending you wouldn't be cutting etc. so even if this were 2 x 10hp motors one would be idling while the other was working so you would never have the load going all at once. or lets say you had the lathe going, you would only be using the lathe and nothing else so i'm now thinking that the single phase will be more than enough to cope.
what do you think with the above circumstances?
and as far as a generator goes, im really not going to go down that route. just another thing to look after and to get a decent one its going to be very expensive.

 

[robertl]

From the information you have supplied, sounds like a base load generator is the answer, may be should have considered your load requirements prior to planning the workshop project, whatever choice you take good luck.

A base load generator would be good, but as i said above i dont think it would be a realistic option price wise to get a decent unit with the power requirements i need.
To be honest i think now looking at the way i am planning to use these machines i.e one at the time. i dont think if i use them like that i will have any issue at all. even using 2 at the time if they were say 5kw each shouldn't be an issue. and as far as any other load goes there will be an LED lighting circuit, several sockets, maybe a radio playing, no electric heating will be installed so the only real load will be the tools and equipment but if only using 1 to 2 of the large units at once i now am starting to think it may be a non issue.
what do you think?
thanks
Robert

 

[Shoei]

Have just asked this very question, and the answer was to upgrade from 100A it would need to be a 3 phase supply.
The guy said that 100A was the max they could supply to any property on single phase.

Is the shed big enough to be split into two 'starter units' that each would need a supply? Agree that 100A is enough to keep a busy workshop running, adding up the worst case usually paints an unrealistically gloomy picture, even in many domestic settings.

 

[robertl]

Is the shed big enough to be split into two 'starter units' that each would need a supply? Agree that 100A is enough to keep a busy workshop running, adding up the worst case usually paints an unrealistically gloomy picture, even in many domestic settings.

Yes it will be 15m long by 10m wide but im thinking ive now written all possible tools and equipment i have and hope to get down and yes if you had 4 of these units running at once it may be an issue but in reality in a 1 to 2 person workshop, even a workshop with 4 or 5 people the chances of having several machines on at once is slim to none. so from that i can be nearly sure it would be less than he 100A or 23KVA available to me.
I'm pretty sure anyway.
If needs be in the future if there was some sort of massive expansion then i suppose 3 phase could be an option

 

[Midwest]

Have you enquired about financial help from the Shetland Islands Council, that they publicise?

Have you enquired if this development would apply?

Financial Assistance

 

[Lucien Nunes]

Are the rotary ones just no good or why dont you reccomend them?

No, it's just a compromise solution. If you have a converter rated for 30hp of load, that has to be running almost idling all the time you want to use a small 3-phase device that can be wasteful. It does nothing to temper the possible heavy starting loads, just makes them bigger and transfers them to the single-phase supply. Then when running, the performance and efficiency of the load motors can be somewhat reduced. An inverter on the other hand can be finely tuned to get the most appropriate starting characteristics for its machine, with a minumum of surge load, and then allows the motor to work at peak efficiency. The main drawback is initial cost, and some motors are not configurable to run from a singe-phase-input inverter.

Would a new secondary supply single phase not be coming from the same place as the three phase supply would need to come from?

As I understand it the transformer feeding the site is single-phase, as is the 11kV overhead line. There might be more single-phase power available from the existing transformer, but to change to 3-phase requires an extra 11kV line and a new 3-phase transformer.

 

[robertl]

No, it's just a compromise solution. If you have a converter rated for 30hp of load, that has to be running almost idling all the time you want to use a small 3-phase device that can be wasteful. It does nothing to temper the possible heavy starting loads, just makes them bigger and transfers them to the single-phase supply. Then when running, the performance and efficiency of the load motors can be somewhat reduced. An inverter on the other hand can be finely tuned to get the most appropriate starting characteristics for its machine, with a minumum of surge load, and then allows the motor to work at peak efficiency. The main drawback is initial cost, and some motors are not configurable to run from a singe-phase-input inverter.



As I understand it the transformer feeding the site is single-phase, as is the 11kV overhead line. There might be more single-phase power available from the existing transformer, but to change to 3-phase requires an extra 11kV line and a new 3-phase transformer.

Thanks for that reply
So as I don't have any of these machines yet, I could buy ones that are either single phase where available, and if not get ones that can be run from inverters.
The other option I found is a digital 3 phase converter, I assume these work with an inverter type set up but not sure exactly.
Do you know about these?

 

[robertl]

And yes there are only 2 overhead 11kv lines, for me to get 3 phase I need to get them to install a 3rd overhead cable around a mile over a hill which just can't be justified financially.

 

[Bellendian]

I honestly think you could get a half decent 3 phase genset and years worth of diesel for less than the cost of getting the dno to upgrade. As far as I know these can be run on red diesel so less tax than road fuels. At the very least it gets the business up and running, bringing in revenue to possibly fund the network connection costs later down the line.

 

[robertl]

I honestly think you could get a half decent 3 phase genset and years worth of diesel for less than the cost of getting the dno to upgrade. As far as I know these can be run on red diesel so less tax than road fuels. At the very least it gets the business up and running, bringing in revenue to possibly fund the network connection costs later down the line.

I have thought about this, since the last message in this I have also specced all the machines I will be using, and I was quite surprised, the max motor size is 7.5kw as I said before but most of the motors for everything else are less than half of that, and even with a 23kv single phase supply I'm quite sure I will get nowhere near that. Maybe in the future if it expands dramatically then it is possible that I may need more and the geni / upgrade option will come in to play, but weel see what happens. Anyway that's my thoughts on it for now.

 

[dmxtothemax]

I think if your carefull about how you use your machines and when ! Then a single phase will work.
Perhaps consider swapping out the three phase motors for single phase motors.

 

[davesparks]

I honestly think you could get a half decent 3 phase genset and years worth of diesel for less than the cost of getting the dno to upgrade. As far as I know these can be run on red diesel so less tax than road fuels. At the very least it gets the business up and running, bringing in revenue to possibly fund the network connection costs later down the line.

The genset and years worth of diesel may be less than the cost of the DNO upgrade, but will it still be less with the next year's worth of diesel? And the next after that?

That option is cheaper now but in 20 years time will have cost a lot more in total,espexially with servicing and repairs to the generator, plus downtime due to breakdowns.

 

[robertl]

I think if your carefull about how you use your machines and when ! Then a single phase will work.
Perhaps consider swapping out the three phase motors for single phase motors.

Yes i have looked at this also, (new motors i mean) but to be honest seeing as im starting out i will hopefully just buy single phase machines where available and if not buy a 240 3 phase capable machine and fit a VFD, with the benefits of start up being reduced etc.

 

[robertl]

You can get pretty well most machines now that will either be single phase or will be capable of 240 3 phase.