Combine 3 x single phase/220v = 3-phase power?

[DownWest]

prv made a general point about using more than one shore supply, I was simply responding that I personally would not be happy to do this for the reasons stated. Obviously I know nothing about the OP's electrical arrangements, however, he did ask " Is it possible to take 3 separate single phase/220v cables from the shore and combine these into the ship's needed 3-phase power?" He seems to only need 3 ph for the water pump, this he is going to have to treat separately, given that, he then only needs the domestic single phase. He could easily run this from a single 32amp supply by connecting the three circuits together. Even a 16amp supply could provide about 3.5kw which is enough for most purposes if you're careful not to switch on too many heavy loads at one time. Having 3 phase in industrial premises, where the wiring has to be regularly checked and certified, is one thing. Having it in the amateur marine environment is another.

You should read the thread a bit more closely. The OP was asking for ideas and then get an electrician to do what was required. No 'amateur' involved.

 

[PaulRainbow]

prv made a general point about using more than one shore supply, I was simply responding that I personally would not be happy to do this for the reasons stated. Obviously I know nothing about the OP's electrical arrangements, however, he did ask " Is it possible to take 3 separate single phase/220v cables from the shore and combine these into the ship's needed 3-phase power?" He seems to only need 3 ph for the water pump, this he is going to have to treat separately, given that, he then only needs the domestic single phase. He could easily run this from a single 32amp supply by connecting the three circuits together. Even a 16amp supply could provide about 3.5kw which is enough for most purposes if you're careful not to switch on too many heavy loads at one time. Having 3 phase in industrial premises, where the wiring has to be regularly checked and certified, is one thing. Having it in the amateur marine environment is another.

I suggest you read the thread. Plenty of info in it to tell you of the OPs "electrical arrangements".

Combining all of his circuits into one system and using a 32a inlet doesn't seem like a good idea, he then has a three phase genset that can only be used to run the grey water pump and is reliant on finding 32a shore power outlets, which are not universally common.

You still miss several obvious things, not least, with my suggestion in post #64 of running multiple 16a connections there won't be any three phase coming onboard, just 1/2/3 standard 240v inlets supplying 1/2/3 standard 240v systems. No more dangerous than a single 16a inlet or your 32a inlet. Even if the OP uses his existing three phase connection, with the exception of one pump, the boat is wired entirely in 240v.

 

[superheat6k]

The boat already has a 3 phase input and a 3 phase generator. The incoming 3 phase (whether from shore power or the genset) is then seperated into it's three 240v phases, each phase is obviously isolated from the other. What i have proposed is to bring up to three 240v inputs onboard and connect them to the existing 240v circuits. With appropriate switching and circuit protection, nothing has changed in terms of safety.

It does not matter if the three incoming supplies are on the same phase or not, the wiring is already installed to reflect that with the current genset and incoming shore power connection that all three 240 circuits absolutely will be on different phases.

Installations such as this are commonplace in industrial settings, where the incoming three phase will supply some of the shop floor and different 240v phases will supply 240v equipment on the shop floor and the offices etc. It's nothing new, back in the 70's my uncle had a new workshop built, the power to the workshop was 3 phase to power the four post ramp. Two 240v phases were taken around the workshop for all of the 240v equipment and the third one went to the house that stood beside the workshop.

There is nothing wrong with this type of installation, it's just your poor understanding that makes you think there might be.

Whereas what you say here is reasonable, you did earlier say to try running a 240v 3 phase delta connected motor from one 240v phase, and neither that nor an attempt to bring in three separate supplies onto this motor would work, indeed the risk to the motor and possibly those around it could be severe, especially should two separate supplies on different phases of the originating supply be somehow connected together.

Indeed should this be done by plugging a second supply phase cable into a shore power receptacle where another phase is already present the 400v full short circuit created would likely explode at the point of connection, bearing in mind at that point the connector would be in someone's hand.

This latter risk is very real for anyone plugging in dual shore power leads into neighbouring shore supply receptacles to double up 16a into a 32a because it is not possible to know without suitable checks beyond most boater's capability if alternate phases have been connected to neighbouring shore receptacles.


In regard to the pedant response on 380, 400 and 415 vac. From 380v 3 phase 220v single phases (to neutral) are derived, 400 > 230v, 415 > 240v. Some years ago the UK nominal supply was changed from 415v +-6% to 400v +10% -4% in order to harmonise supply and design across the EU. This means the UK supply can still be legally as high as 440v, and many London sites I visit have site voltages at or above 425v. This can be a problem for 380v / 220v designed equipment because the nominal equipment voltage tolerance is normally 10%, so for 380v a maximum of 418v, so at 425v the equipment will be seeing a distinct excessive voltage. Generally most single phase equipment from Europe is now rated for 230v, and this will generally work fine on most 240v supplies, even though 250v measured is not uncommon at many sites in the UK. My house is 246v and the supply to my boat when on shorepower is 242v.

 

[JumbleDuck]

This latter risk is very real for anyone plugging in dual shore power leads into neighbouring shore supply receptacles to double up 16a into a 32a because it is not possible to know without suitable checks beyond most boater's capability if alternate phases have been connected to neighbouring shore receptacles.

A point first made in .... <scrolls back to check> ... post #7, just seventy four postings earlier.

 

[PaulRainbow]

Whereas what you say here is reasonable, you did earlier say to try running a 240v 3 phase delta connected motor from one 240v phase, and neither that nor an attempt to bring in three separate supplies onto this motor would work, indeed the risk to the motor and possibly those around it could be severe, especially should two separate supplies on different phases of the originating supply be somehow connected together.

Indeed should this be done by plugging a second supply phase cable into a shore power receptacle where another phase is already present the 400v full short circuit created would likely explode at the point of connection, bearing in mind at that point the connector would be in someone's hand.

This latter risk is very real for anyone plugging in dual shore power leads into neighbouring shore supply receptacles to double up 16a into a 32a because it is not possible to know without suitable checks beyond most boater's capability if alternate phases have been connected to neighbouring shore receptacles.

I suggested trying the motor at 240v, but missed that it was delta, pointed out to me in post #50

I have not suggested connecting three separate 16a inputs to the three phase motor, i have clearly stated that i would disregard the three phase pump when in port, unless using the genset. Post #46 details my suggestion for connecting more than one 16a inlet and this does not pose any of the risks you detail above, it's just all simple, straightforward 240v connections, no three phase involved.

 

[superheat6k]

A point first made in .... <scrolls back to check> ... post #7, just seventy four postings earlier.

Except that is not what it says !

Very few posts on here have referred to just how dangerous 3 phase 400vac and potentially mixing phases is - I am surprised you wish to be pedantic about this.

 

[PaulRainbow]

Except that is not what it says !

Very few posts on here have referred to just how dangerous 3 phase 400vac and potentially mixing phases is - I am surprised you wish to be pedantic about this.

Probably because we are not suggesting mixing phases, in fact, no-one is even talking about bringing three phase onboard. There is nothing whatsoever wrong with bringing more than one 16a supply onboard and keeping them on separate circuits, big mobos have been doing it forever.

 

[Alex_Blackwood]

IMO this subject is far too dangerous to be discussed on a forum where to be honest not everyone knows what they are talking about. No disrespect intended. Also replies can be mis-read and misconstrued. The OP needs professional advice , on site.

 

[PaulRainbow]

IMO this subject is far too dangerous to be discussed on a forum where to be honest not everyone knows what they are talking about. No disrespect intended. Also replies can be mis-read and misconstrued. The OP needs professional advice , on site.

You are correct that this "should not be tried at home". The system, from an end user perspective, is safe and simple. The actual design and installation isn't something that should be attempted as a DIY installation though.

But, see post #1:

Needless to say, I'll get a licensed electrician to install it, so this post is just for my background info and to have a reasonably educated conversation with the electrician.

 

[DownWest]

IMO this subject is far too dangerous to be discussed on a forum where to be honest not everyone knows what they are talking about. No disrespect intended. Also replies can be mis-read and misconstrued. The OP needs professional advice , on site.

Granted, but very few people reading this forum are likely to have 3-phase on their boats. Some of us are, like Paul, professional electricians, or like me, where my house was 3-phase and I was dealing with domestic generators up to 60kva, Usually 3-phase upwards of 16kva And, have sorted single phase standby gensets supplying 3-phase houses, not far from what the OP's situation is.
No doubt the OP will pass this under the nose of his electrician and he will filter out the less useful bits.

 

[rolf.nielsen]

Yes and thanks for all the input. I hadn't expected 90 posts on this, this forum is great and I have learned a lot which was the objective of making the original post. Everyone can rest assured that only licensed electricians will get to mess with any of this on my ship. These many posts will have helped me, however, to have a better discussion with the electrician instead of just pointing at my ship and say 'go fix'.

 

[Graham_Wright]

Yes, but it was a fiddle. Although EU standard is nominally 230V, there is a sufficiently large tolerance band (+/- 5%, from memory) to allow the UK to continue on 240V and furriners to continue on 220V, as before. Last time I measured mains voltage here, a couple of weeks ago, my meter said 239.5V

It's -6 +10. My machine declines to switch on below 220v.
In my previous premises, the traction engine restoring neighbour used heavy welding kit. The farmer up the road made numerous complaints to the (then) MEB about his rather dynamic tv picture sizes. Every time the MEB called to investigate, the welding had stopped.
At the time, my machines ran off a generator but business expansion called for more power.
Connecting as many high power loads as we could muster, the recording voltmeter results were forwarded to MEB who admitted they had a problem and installed a new transformer and three phase feeds to all the business premises.

185 volts for the 10 minute duration of the experiment convinced them!

 

[Kinsale373]

Spot on. Sorry if I didn't explain it well enough earlier. I have one pump that needs 3-phase power, all the rest of the systems onboard are 220v, run off single phases that are split off from the main 3-phase supply.

So I understand the suggestion is to feed each of the 3 on-board single-phase systems with a single-phase 220v supply from shore. I have to check that the galvanic separator is placed correctly in this system, but otherwise it's a simple and good solution. I'll then only be left with my 3-phase pump. Let's assume it runs at 4000w so that a single phase of 16 A power can't pull it. Let's also assume that it needs to be that powerful and that I can't change it to a smaller and/or a single phase pump. What do I do with that pump then?

You can't get 3 phase from several single phase with going to considerable expense and on some occasions during high season you may scramble to get a single connection!

The deciding factor here is to know how much power the 230V appliances (excluding the 3 phase pumps, require). Can everything excluding the pump be run from A 230V single supply ?

If so, then replace your pump. I'd be surprised if a good pump supplier cant sell you a lower power 230V pump that will do the job at reasonable cost . What's the issue if it takes 15 mins to pump out grey water tanks instead of 10 ? I've seen small 230V submersible pumps doing amazing work .
For this to work you just need to rewire your 230 volt units back to the one supply connection on the incoming 230V shore power line. (Replace the 3 Phase socket witha single phase) . You probably won't need to run most of you 230V at the same time anyway- ie don't pump out the the Grey water if the Emersion or the washing machine is running. This is a fairly low cost solution.

If you absolutely need more power than a single 230V supply can deliver , then I think that a 3 phase diesel genny is the most appropriate solution.
a 15KVA 3 phase will deliver approx 20A per phase. Now you will need to check again if 15KVa or 60A across 3 phases is enough. If it is, then its a good solution as you need very little wiring. A 15KVA ( Not a a marine version) costs around £6K plus you'll have installation costs. But you'll be fully independent of marina supply which is nice

Kinsale373

 

[PaulRainbow]

You can't get 3 phase from several single phase with going to considerable expense and on some occasions during high season you may scramble to get a single connection!

The deciding factor here is to know how much power the 230V appliances (excluding the 3 phase pumps, require). Can everything excluding the pump be run from A 230V single supply ?

If so, then replace your pump. I'd be surprised if a good pump supplier cant sell you a lower power 230V pump that will do the job at reasonable cost . What's the issue if it takes 15 mins to pump out grey water tanks instead of 10 ? I've seen small 230V submersible pumps doing amazing work .
For this to work you just need to rewire your 230 volt units back to the one supply connection on the incoming 230V shore power line. (Replace the 3 Phase socket witha single phase) . You probably won't need to run most of you 230V at the same time anyway- ie don't pump out the the Grey water if the Emersion or the washing machine is running. This is a fairly low cost solution.

If you absolutely need more power than a single 230V supply can deliver , then I think that a 3 phase diesel genny is the most appropriate solution.
a 15KVA 3 phase will deliver approx 20A per phase. Now you will need to check again if 15KVa or 60A across 3 phases is enough. If it is, then its a good solution as you need very little wiring. A 15KVA ( Not a a marine version) costs around £6K plus you'll have installation costs. But you'll be fully independent of marina supply which is nice

Kinsale373

Wow !!!!!!

Have you actually read any of this thread at all ?

 

[Kinsale373]

I have read all the inputs , So whats you point where to you disagree with what I'm suggesting Paul!

 

[PaulRainbow]

Apologies if it looks like i'm picking this apart ( i suppose i am, no offence intended), but it does look very much like you haven't read what's been said previously.

You can't get 3 phase from several single phase with going to considerable expense and on some occasions during high season you may scramble to get a single connection!

I'm not aware of anything that can do this, although i'm not an industrial electrician. It would be a pointless exercise anyway, the only thin on the boat that is 3 phase is the grey water pump, so if such a device existed you'd be creating 3 phase, only to split it back into separate single phase systems one onboard (except for one pump)

The deciding factor here is to know how much power the 230V appliances (excluding the 3 phase pumps, require). Can everything excluding the pump be run from A 230V single supply ?

Given that the boat is 65 feet and has a long list of electrical equipment, i single 240v supply would be extremely limiting.

If so, then replace your pump. I'd be surprised if a good pump supplier cant sell you a lower power 230V pump that will do the job at reasonable cost . What's the issue if it takes 15 mins to pump out grey water tanks instead of 10 ? I've seen small 230V submersible pumps doing amazing work .

Can't argue with this, but it's been suggested several times and the OP doesn't want to change the pump.

For this to work you just need to rewire your 230 volt units back to the one supply connection on the incoming 230V shore power line. (Replace the 3 Phase socket with a single phase) . You probably won't need to run most of you 230V at the same time anyway- ie don't pump out the the Grey water if the Emersion or the washing machine is running. This is a fairly low cost solution.

Permanently restricting a 65 foot boat, fully loaded with 240v equipment isn't a great idea, IMO. Not only is it too restrictive, it makes the existing 3 phase genset redundant. Post #64 details how to supply the boat with two 16a supplies, when available, and still keep the option of using the genset at sea, when no shore power is available, or when requirements exceed single 16a supply. It also allows the OP to continue using his 3 phase pump. Finally, it allows him to use a 3 phase supply from the marina, when available.

If you absolutely need more power than a single 230V supply can deliver , then I think that a 3 phase diesel genny is the most appropriate solution.
a 15KVA 3 phase will deliver approx 20A per phase. Now you will need to check again if 15KVa or 60A across 3 phases is enough. If it is, then its a good solution as you need very little wiring. A 15KVA ( Not a a marine version) costs around £6K plus you'll have installation costs. But you'll be fully independent of marina supply which is nice

How is a 3 phase genset going to work, now that you've got him to connect all onboard services to a single system ? You also had him change his pump to single phase, so that won't run from the genset. But, more importantly, he already has a 3 phase genset, that powers all of his 240v equipment by splitting the phases, whilst running the 3 phase pump. This is the main reason i asked if you had read the thread

 

[pawl]

I don't think that it is me that is missing the point here, if the OP were to adopt your advice he would need 4 cables coming from the shore power, one for each of the 3 ph circuits and another to run the pump. IMHO he will need a 32amp supply for the pump whatever. He would not be able to connect the 3 x 16amp supplies together in case they were not tapped from the same phase. The point I'm trying to make here, which is a general one, is that unless you have intimate knowledge of the particular marina's wiring you could be running the risk of picking up different phases if you take a supply from more than one source. Even if you think that you have all the phases separated there is still the neutral which is common to all phases. It wouldn't take much of a fault to potentially have a 415 volt hazard with the risk of electrocution or fire.

 

[pawl]

Sorry, my last post (97) was intended as a response to PaulRainbow's post no.82.

 

[PaulRainbow]

I don't think that it is me that is missing the point here, if the OP were to adopt your advice he would need 4 cables coming from the shore power, one for each of the 3 ph circuits and another to run the pump. IMHO he will need a 32amp supply for the pump whatever. He would not be able to connect the 3 x 16amp supplies together in case they were not tapped from the same phase. The point I'm trying to make here, which is a general one, is that unless you have intimate knowledge of the particular marina's wiring you could be running the risk of picking up different phases if you take a supply from more than one source. Even if you think that you have all the phases separated there is still the neutral which is common to all phases. It wouldn't take much of a fault to potentially have a 415 volt hazard with the risk of electrocution or fire.

You are missing the point and clearly have absolutely no idea how this all works, so why don't you leave it to those that do ?

He doesn't need a 32a supply for the pump, the pump is 3 phase, that gets powered by 3 phase shore power when it's available or the genset, same is it does now, nothing has changed in this respect.

How many times do i have to say this the three incoming 16a supplies are not connected together

It doesn't matter where the marina is and it doesn't matter if the three supplies are all one phase or all different, they are three totally independent 240v single phases.

All circuits will be double pole installations.

How do you get a 415v hazard from a 240v installation, you cannot.

This is what i do for a living. The concept of having more than one incoming 16a single phase supply isn't something i just dreamt up, boats have been wired like this forever.

 

[PaulRainbow]

Sorry, my last post (97) was intended as a response to PaulRainbow's post no.82.

Remind us all, what do you do for a living ?