# 240 Volt Conversion



## CLS (Jul 25, 2005)

Thinking of buying a step up / step down transformer :

http://www.airlinktransformers.com/auto.asp

Can anyone advise is it just a case of one feed in 240 volts and the other connection to the generator giving 110 volts ? :?

At present i have a site transformer 3kva that my 240 volt mains goes into dropping everything down to 110 volts , then it goes to another site transformer bringing it back to 240 volts , obviously between the two points it,s able to feed the 12volt system and the 110 volt appliances. :? 
The 110 volt transformer gets very hot and keeps tripping out till it cools down :roll: .......not an ideal situation

Any advise greatly appreciated

Cheers Mark


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## olley (May 1, 2005)

Hi mark, yes put 240v in on one side and you get 110v out the other, reverse it and you get 110v in 240v out.

That what I have on mine, different tranny but same idea.

Olley

You will need some means of stopping both genny and shoreline being connected at the sametime. Either manual or automatic


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## CLS (Jul 25, 2005)

Olley if i connect the 240 volt from the mains hook up to the 240 connection and then connect the generator feed ( 110 volts ) to the other connection is it really just that simple ? :? 
I have fitted an in line fused switch to swap between generator and mains operation which seems to work ok .

Cheers Mark


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## Scotjimland (May 23, 2005)

Hi Mark

Not trying to hi jack your thread with Olley ..think he's gone awol :lol: 

Yes to your question, it's that simple.. what size of tranny are you buying ?


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## CLS (Jul 25, 2005)

Hi Jim ......thinking of buying the 3000 va , presume thats 3kva , 
Do you think that would be big enough ?

Cheers Mark


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## Scotjimland (May 23, 2005)

Hi Mark 

Ours is 3kva and it gets pretty hot at times .. I was going to upgrade to a 5kva.. 
Bear in mind UK 16 amp hook ups ~ 3.8kva so maybe it's not worth the extra £50 and of little use abroad :?


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## CLS (Jul 25, 2005)

Is that the yellow box type that has the 2 X 110 volt outlets ? If so that,s like mine and thjat overheats just using the microwave and normal appliances. :? 

I take it when using both aircon units you are powering of the generator ? as when i tried on site on mains it tripped the site supply straight away.

Cheers Mark


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## LC1962 (Oct 6, 2005)

Hi Mark,
We use Airlink, never had a problem.
You have PM
 

Cheers
Linda


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## Scotjimland (May 23, 2005)

Sorry Mark. I edited as you answered... :?


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## Alan1234 (Jul 20, 2005)

Hi Guys 

I just happened to pose a related question to my electrician the other day, he's a very long time RVer. 

"What would you do to your rig if you took it to Europe and were faced with 240 volts of unreliable amperage in camp sites" 

His answer surprised me a bit, he said that voltage is not an issue for american appliances once stepped down because of recent reductions to the supply systems and they'll often tolerate down to 100 v, but they don't like 50 cycles one bit, and of course amps is amps, you can't get what they don't give you. 

He said he'd run everything on batteries using the built in AC converter for 110 use, and when solar was not sufficient to recharge, run the site power through a stepdown transformer and into the battery charger. He claims that if the charger is not undersized you can run microwaves etc for quite a while thus. 
His TV is DC (battery) and his interior lights are all replaced with fluorescent which he claims saves a lot of power 

His overall attitude was to be as self sustaining as possible (not in a survivalist way!) but to have lots of potable water, black water capacity, battery power, just to not always be running around looking for a hook up. 

He did say that 4-5 years is about it for the house battery set, and that monitoring is important, he mentioned golf cart batteries as constantly proving themselves the most reliable and load tolerant of all the special use batteries. 

There is also a device which converts excess DC voltage from the solar panels into amperage and thus increases their overall charging rate on days like today- (it is a beautiful cloud free sparkling California day in old Blighty is'nt it?)  (silly grin) 

Alan


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## gromett (May 9, 2005)

Please excuse me if I am missing the point here, been awake too long.

You can't reverse a transformer. If you have a transformer that is designed to convert 240 -> 110 you can't put 110 in the secondary winding to get 240 out. I can explain the technicalities if you want but they are a little more complicated than that.

If you buy an RV from the states and want to use 240v equipment, logically speaking you will need 2 transformers.
1 step down transformer on the input. This will convert the 240 to 110 that you will feed to the charger.

The second will be a step up transformer that goes from the inverter to supply the (new) 240V sockets. The inverter will still supply the 110 to the US supplied appliances that you have left in place. The transformer will supply the 240v to the socket for the UK spec equipment you want to plug in.

Cheers
Karl


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## Scotjimland (May 23, 2005)

Quote: Karl: 
_You can't reverse a transformer. If you have a transformer that is designed to convert 240 -> 110 you can't put 110 in the secondary winding to get 240 out. I can explain the technicalities if you want but they are a little more complicated than that._

Hi Karl.. 
look at the first post.. and the link, these transformers are step up or step down.

Only one transformer is required in an RV, to step down from 240 to 110. This feeds the battery charger, air con, microwave, fridge and any other 110v appliances. 
If you install 240v sockets they are fed direct from mains or the genny via the same transformer only using it as step up from 110 - 240v . 
To prevent both supplies being on at the same time a changeover switch is used, our's has a common site transformer and it works fine albeit a little underrated.. at only 3kva..

I have a 600 watt Mobitronic invertor which is only used to feed the TV and digi box or supply and charge the laptops.


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## gromett (May 9, 2005)

olley said:


> Hi mark, yes put 240v in on one side and you get 110v out the other, reverse it and you get 110v in 240v out.


Sorry, my post was in response to Olley's post. I apologise for any confusion. As I said I was sleep deprived 

Cheers
Karl


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## gromett (May 9, 2005)

Just a quick point to watch out for. The cheaper transformers are autotransformers. These are lighter and cheaper but as they only have 1 winding are riskier from a safety point of view. On a normal split winding transformer there is physical seperation of the primary from the secondary so there is no easy way for 240v to end up on the 110V side. With an autotransformer this is possible.

Cheers
Karl


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