How to Convert 120V Single Phase to 440V Three Phase for a Diving Tender Boat?

[buckland23]

Hi there,
i'm trying to do a technical paper on converting 120 volt single phase to 440 volt 3 phase for a diving tender boat. Does anyone know what things i should be concerned about when trying to convert the power. The boat usually runs in generators alongside but, i was hoping to hookup marina 120 volt power into the boat. The boat usually draws around 30-45 amps alongside.
Would a rotary phase or static phase converter work? Any help would be greatly appreciated

thanks
Scott

 

[Bobbywhy]

A single phase 120V input mechanically rotating motor-three phase generator would work.
Also a static converter could work. I would use Google and Amazon to search out companies that make them.

Here's one: http://www.dtims.com/products/obvp/

 

[russ_watters]

The amperage might be prohibitively high though...

 

[Bobbywhy]

True, the amprerage draw may be high. I did not do any calculations. The OP did mention the dockside power source supplied 30-45 Amps at 120V. For this project a proper power budget must be done.

 

[buckland23]

whats a power budget? Is it a power consumption total of all the things running alongside

 

[jim hardy]

"""The boat usually draws around 30-45 amps alongside.
""

is that forty-ish amps from the three phase 440 or from the single phase marina power?

3 phase power is Volts X Amps X √3
and of course single phase is just Volts X Amps.

be aware also that rotating machinery will have an advantage during brief overloads , such as in starting a big compressor motor.
electronic inverters of the 1980's had substantially less stout overload characteristics than generators. i would guess they still do.

 

[buckland23]

right now the boat is just running on one of its big generators alongside. I was hoping to come up with a way to supply the 440v 3 phase from the marina/docks 120v supply. This would probably be cheaper than paying for fuel to run a big generator all night

thanks again for all your help

 

[Bobbywhy]

Can you verify here that the dockside power source you intend to use for your power converter is single phase, 120 Volts?

 

[jim hardy]

a technical paper? sure sounds real.

you mentioned 40-ish amps

well, 440 volts 3 phase at 40 amps is 30.5 kw

and to get 30.5 kw from a 120 volt supply would take 254 amps. the wire size gets impractical to manhandle.
you ought to get current measurements,
and see if the marina has three phase.
A 40 amp 440 volt three phase extension cord is not unheard of.

 

[buckland23]

all the marinas i spoke to along the east coast of vancouver island were 120v single phase. The amperage ratings were mostly 30 amp up to 100 amp. Campbell River did have 3 phase but they were the only one. Thanks for the info regarding wire size. Thats why i wanted to get some advice before i started my paper. I just thought they could be a better way than to run on the ships generators all night when we are alongside a marina. Not only does the noise bother the neighbours but we are burning lots of fuel. I might have to do another topic for my paper

thanks again
scott

 

[NascentOxygen]

all the marinas i spoke to along the east coast of vancouver island were 120v single phase. The amperage ratings were mostly 30 amp up to 100 amp. Campbell River did have 3 phase but they were the only one.

Please bear with me while I labour the point here. Despite the marina saying they only have single phase, examination of the supply cables may reveal that they are indeed supplied with 3 phases. It may be worth pursuing this further. The marina may just be reporting that there are no 3 phase sockets for you to plug into to. You'll need to ask them how many overhead wires they are supplied from, if overhead; or some other revealing question.

The power company may have put 33% of the single phase power outlets on each phase for load balancing. I don't know whether they routinely do this; I'm just saying it's conceivable that they may. Where there are a host of power outlets, including 100A outlets, I'd be surprised if the place isn't using all three phases.

If you find they do have 3 phases, all you'll need are 3 transformers 100v:250v and some switches and breakers, etc. That is so much easier than what you are otherwise looking at.

 

[NascentOxygen]

I just re-read your post. I see it's not just one marina, but multiple marinas, where you wish to dock. My other question is--what does the boat use/need 3 phase power for? I'm wondering whether single phase might suffice, and while docked power all GPOs from a single phase, and run the boat's generator for 1 or 2 hrs a day if three phase is needed only intermittently or for only a few hours? Though that might be a bit tricky to arrange.

 

[jim hardy]

indeed see what the boat does with that 3 phase
and whether that 40 amps is all the time or just when something big is running

i saw a computer system once where manufacturer demanded it be supplied 3 phase 230 volt power
but one of the terminals wasn't even connected to anything inside the chassis
and it ran fine on good ol' 230 centertapped housepower.

Nascent's suggestion is common sense.

 

[Averagesupernova]

i saw a computer system once where manufacturer demanded it be supplied 3 phase 230 volt power
but one of the terminals wasn't even connected to anything inside the chassis
and it ran fine on good ol' 230 centertapped housepower.

Sounds like my former boss. I suggested he run a new 230 volt single phase circuit out of a certain breaker box. His reply was: "You can't do that! That's 3 phase!" Of course it was three phase delta, but he somehow thought legs A and B were somehow different in that box than legs A and B in the box on the other side of the wall which didn't contain the C leg.

 

[jim hardy]

Well, Av'SuperNova -- thanks!

i helped a friend with that one.
his boss had just contacted the power company to have a new pole pig installed and three phase brought into the building for the computer. when my buddy called him and said we'd got it going already, he was ecstatic.

needless to say we got a nice steak dinner ...