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# 3PH to 1PH Converter

05/06/2012 7:10 AM

I need to derive 1-ph power either from a 1-ph source or 3-ph source. Even in 3-ph source sometimes there is chance of availability of one phase or two phase or Three phase. Under any of the above circumstances I need to derive 1-ph power output with or without manual intervention. Kindly advise.

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#1

### Re: 3ph to 1ph converter

05/06/2012 8:15 AM

If you do not know how to safely change a three phase voltage source into a single phase voltage source, then you need an electrician. This is such a basic fundamental electrical problem that tells me that you are obviously unqualified to work on three phase power of any voltage. It is true that doing your own electrical wiring is easier than doing surgery on yourself. Performing surgery on yourself only risks you. Doing your own electric wiring risks anyone in your building and anyone who works on that circuitry after you leave. Get an electrician.

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#2

### Re: 3PH to 1PH Converter

05/06/2012 11:31 AM

As I see it this is not as simplistic as your title implies, you want a way of automatically switching the source of line power from any one of three input phases and get a sinle phase output, or even have an input that starts out as single phase to begin with. It is a challenge.

But you don't supply quite enough information.

1) What is the configuration of your 3 phase power, Star or Delta? If you are not in the US that may not be a consideration to you, but to us, Delta is a possible choice which would render this all but impossible without a motor-generator set. So if you are an equipment OEM and planning on marketing this machine in the US, you should reconsider your input power situation altogether, i.e. change to DC perhaps.

2) What is the single phase voltage you need for your output?

3) What is your load? I.e motors, resistive heaters, solid state power supplies etc.

4) How much power are you talking about? 1A, 100A, 1kA, 100mA?

5) You say that you want it to automatically change but how fast is acceptable? 1sec, 2sec, 100msec, 10msec? Be realistic, bump less transfer is extremely expensive unless you use a UPS, which then comes back to the amount of power you need.

6) Is it OK that the user select the incoming configuration ahead of time and it just automatically switches, or do you need it to automatically detect the incoming source and do everything with zero user input?

7) What is your budget like to accomplish this? I.e. I can build you anything you can sketch on the back of a big enough check, but if you think you are going to get this for \$100US, let's just stop now!

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Good Answer (Score 2)
Anonymous Poster #1
#5
In reply to #2

### Re: 3PH to 1PH Converter

05/15/2012 10:53 AM

As I see it this is not as simplistic as your title implies, you want a way of automatically switching the source of line power from any one of three input phases and get a sinle phase output, or even have an input that starts out as single phase to begin with. It is a challenge.

But you don't supply quite enough information.

1) What is the configuration of your 3 phase power, Star or Delta? If you are not in the US that may not be a consideration to you, but to us, Delta is a possible choice which would render this all but impossible without a motor-generator set. So if you are an equipment OEM and planning on marketing this machine in the US, you should reconsider your input power situation altogether, i.e. change to DC perhaps.

2) What is the single phase voltage you need for your output?

3) What is your load? I.e motors, resistive heaters, solid state power supplies etc.

4) How much power are you talking about? 1A, 100A, 1kA, 100mA?

5) You say that you want it to automatically change but how fast is acceptable? 1sec, 2sec, 100msec, 10msec? Be realistic, bump less transfer is extremely expensive unless you use a UPS, which then comes back to the amount of power you need.

6) Is it OK that the user select the incoming configuration ahead of time and it just automatically switches, or do you need it to automatically detect the incoming source and do everything with zero user input?

7) What is your budget like to accomplish this? I.e. I can build you anything you can sketch on the back of a big enough check, but if you think you are going to get this for \$100US, let's just stop now!

Thank you very much for your analysis Mr JRaef. Please find the following information on your questionnaire.

1) 3-Phase Power is of Star connected i.e., (3-Ph + Neutral). It is in India.

2) Single Phase output Voltage needed is 230V (1Ph+Neutral).

3) Load includes Lighting (Flourescent and Incandescent), Fans, Air Conditioners and some Solidstate like TV.

4) Power requirement would be approximately 10Amp.

5) Changeover time may be Ok from 1sec to 2sec.

6) It shall be detected automatically and do with zero user input.

7) Budget does not matter. It is required for house and not for manufacturing and marketing.

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#3

### Re: 3PH to 1PH Converter

05/06/2012 3:09 PM

You should be able to use one of the phases and the neutral (if you have one) to get your single phase supply. Alternatively you would need a single phase step-down transformer.

Don't bother trying to get phase redundancy, most of the time the protection on the grid will open-circuit all three phases at once (for example a power cut, car vs pole power loss, etc) rather than only one. Keep it simple.

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#4

### Re: 3PH to 1PH Converter

05/06/2012 7:38 PM

If manual intervention is acceptable for one-time setup, a multi-tap transformer might be your best bet. (Much less expensive than an auto-detect-and-connect system.)

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### Users who posted comments:

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