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-   -   Converting std 220v/60hz to Single phase 240V 3-wire (http://www.diychatroom.com/f18/converting-std-220v-60hz-single-phase-240v-3-wire-1144/)

jryali 10-15-2005 07:17 AM

Converting std 220v/60hz to Single phase 240V 3-wire
 
I am trying to make my clothes dryer from the US (electrical - requires single phase 240V 3-wire) work in India (standard electrical supply is 22V 60hz). I cannot use a regular voltage convter because that gives me 120V/50hz output.

One of the other postings on this forum explained that a 3-wire 240V is nothing but two hot 120V wires and 1 ground. Does this mean that I can use a standard voltage converter, extract two 120V connections, connect each

Will the following approach work?
- use a standard voltage converter with multiple outlets to get 120v 50hz supply
- connect 1 hot wire to the hot wire from one outlet (120V)
- connect 2nd hot wire to the hot wire from a different outlet (120v)
- connect ground to ground

If this is not going to work, can someone suggest a method that will?

Speedy Petey 10-15-2005 05:37 PM

The problem is the dryer is not 240, it's 120/240v. It has two hots, neutral and ground. The service in India is 220v, not 120/240 if I am not mistaken.
For most purposes, 220 and 240 are essentially the same thing.
But 120/240 is not the same as either.
Sorry, but this will NOT work.

If it were me I would just get the proper dryer to work with the Indian power requirements.

playintennis5274 10-15-2005 08:57 PM

converting std 220...
 
hEY , YOU COULD ALWAYS USE A CLOTHES LINE....

jryali 10-15-2005 09:40 PM

Speedey Petey,

I understand that I cannot use the standard 220 V available in India, but let me ask the question differently. I can buy a voltage converter that will give me 120V supply like in the US. Is it possible to use this supply to create the right outlet that gives 120/240 that the dryer requires? For example, in the US, if there is no 3-wire 120/240 outlet available, can you use the 120v supply and wire together the required outlet for the dryer?

Thanks.

BigA 10-15-2005 10:53 PM

Find out if your Dryer power supply is a 3-wire or a 4-wire.

If it is a three wire supply, then you might be in luck - it means your dryer was designed to use 2 hots (120V), a ground, and no neutral. Your dryer is looking for a total potential difference of 240V between the two wires which it gets in the US when the two 120V hot wires are not the same phase. If you simply connect your 220V to one side of your dryer's supply, and your Neutral to the other side of your dryer's supply it should work fine.

If it is a 4 wire supply, then it is going to be a bit harder. It means your dryer takes the two 120V for the 240 stuff, but it also uses one of the 120's and the neutral for something as well - probably the control module. If this is the case, you can probably still make it work, but it will probably be more trouble than it is worth.

Speedy Petey 10-16-2005 12:04 AM

BigA, You have it backwards. A 3-wire dryer circuit has two hots and a NEUTRAL, but no ground. The ground is bonded to the neutral inside the dryer.

jryali, What you propose is not legal or safe to try to do.
Honestly, I cannot say what is available in India. There may very well be a converter or transformer to go from the Asian 220v to an American style 120/240 4-wire. I seriously doubt it though.
Is an Asian dryer out of the question?

jryali 10-16-2005 12:46 AM

Speedey Petey, a couple of clarifications:
1) I am not planning to the work myself, but gather the necessary information and have a professional electrician do the work
2) I don't expect to find a converter that gives me a 3-wire 120/240. That's why I asked whether a licensed electrician in the US can build a 3-wire 120/240 outlet required by most electric dryers using the standard 120V supply available? If yes, I can ask the electrician here to do the same using the output of a voltage converter that gives me 120V.

Asian dryer is a possibility, but since I lugged my dryer all the way here, I am trying to figure out if I can use it here with the help of a professional.

Thanks for your time and advice.

Speedy Petey 10-16-2005 07:32 AM

If you are asking if it can be done with only 120v then no.
A dryer needs a 120/240v - 30 amp circuit. There is NO way this can be attained with just a single 120v feed, regardless of amperage.

If you are there now I would ask around local contracotrs. Maybe this has been an issue before. But like I said, you would need a transformer to make 220 with a neutral out of straight 220.
I have never had to consider this so I would not even know if it is available in the US.
Sorry.

jryali 10-16-2005 09:09 AM

Speedy Petey, thanks for the suggestions. Somebody told me (not on this forum) that a centertap transformer might do the trick - similar to your suggestion about a 220 with neutral in the middle.

I will try my luck with a local contractor.

pfil 03-23-2009 09:36 AM

Jryali,
My problem is the same as yours and I was thinking about doing the same as you proposed along with your question. I live in a country with 240v single phase and trying to use a US dryer designed to work with 120/240v.
I have a step down converter with two 120 outlets. I thought about creating a 240v by combining two 120v exactly the way you thought about doing. Before I do that, I'm thinking about bying a voltimeter to confirm which type of voltages I get with that solution.

If you found another solution by using the centertap converter, please let me know. I have not tried any but still theorizing what should work better.

I really don't want to burn anything in this dryer.

thanks for your help.

Daniel Holzman 03-23-2009 10:18 AM

The United States does not use single phase power for residential installations, instead it uses a system properly known as split phase. This means that a single 240 volt phase off the street transformer is center tapped to produce two legs at 120 volts each with respect to neutral. Think of it as one leg is -120 volts, the other is +120 volts, so if you check voltage between the legs, you get 240, while if you check voltage between either leg and neutral (or ground) you get 120 volts.

I do not know what system India uses, however when I was in Italy I noticed that they run 240 volt single phase (this is different than U.S. 240 volt split phase). If India runs 240 volt single phase, and you need a 120 volt line to run the control panel (as noted, this is common on dryers), you would need a step down transformer to reduce 240 to 120 volt. This is definitely going to be a job for an electrical pro, but certainly is possible. My guess is you can buy a used appliance for less than the cost of a properly wired circuit, but who knows, you are in India.

Speedy Petey 03-23-2009 10:30 AM

Daniel, the typical residential system in the US is single phase, as well as split-phase.

rgsgww 03-23-2009 10:38 AM

It might be possible with the right transformer, but you would most likely need to run a bigger circuit, transformers are not 100% efficient.

Also, the transformer would be big, run hot, not to mention cost a lot of money. It might be better to get a new dryer.

AllanJ 03-23-2009 11:24 AM

I would not do this project without a Ph.D. in electrical engineering.

The main stumbling blocks are: (1) the high current load of the heating element and (2) the power supply frequency.

What could be done is to rewire the dryer to separate out the heating element (240 volt) from everything else (I guess the motor is 120 volt too; check its nameplate). Have the 220 volt 50 Hz line connected directly to the heating element with appropriate switches and/or relays. Have a voltage and frequency converter provide 120 volts at 60 Hz for everything else inside the dryer.

Generally you can run a 50 Hz motor (not used for timing purposes) on 60 Hz (too high) with just a slight decrease in its horsepower but you cannot run a 60 Hz motor on 50 Hz (too low) without danger of overheating.

A typical U.S. home electrical supply is called 120/240 volt 60 Hz single phase and is provided by a utility company transformer with a center tapped secondary where the center tap is grounded and serves s the neutral. To get 120 volts from a "plain" 240 volt system requires your own transformer or autotransformer.

You may not use hot to ground on a plain 240 volt circuit anywhere in the world to get 120 volts.

hayewe farm 03-23-2009 01:24 PM

1 to 1 transformer with a center-tap secondary would work and would heat your house at the same time. 2 step-down transformers with the right legs commend would also work. However you may still have a problem with the timmer moter and dryer motor if India is 50Hz.

The US residential electricity is single phase because all three legs are in phase with each other.


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