No, it is not possible to parallel because each of the secondaries of the isolation transformers are out of phase, most likely 120 degrees out of phase from each other. Thus, one isolation transformer may be at peak, while the other will be on a lower value. Thus you get a short circuit with one transformer trying to feed the other due to different voltages present at a given instant. If these were rectified to DC, then you could parallel the DC outputs for more current, but you cannot mix out of phase AC voltages together

 

What's your definition about Transformer 1, 2, 3 ?, that's transformer is SINGLE-PHASE not THREE-PHASE, don't think about previous question !

ALL 3ph transformers consist of three 1ph versions, in fact you don't need them on the same frame, just hook them up the same way separately ( often done) and you create a 3ph transformer.
Like I said, a 3ph transformer IS three 1ph versions.
The answer to your question, again is NO per your DWG.

 

Read My Question... Is connect multiple transformer in parallel possible ? Yes or Not ?, not with this question nor context, but generally, If you still answer No, Is better for you to not answer my question !

You've been told several times by several people that combining three-phase line voltages in the method you described won't work to produce the single phase output.
Your question has been answered but you chose not to believe what you've been told. That usually means you don't understand the basic AC electrical theory behind the questions you are asking.

 

No, it is not possible to parallel because each of the secondaries of the isolation transformers are out of phase, most likely 120 degrees out of phase from each other. Thus, one isolation transformer may be at peak, while the other will be on a lower value. Thus you get a short circuit with one transformer trying to feed the other due to different voltages present at a given instant. If these were rectified to DC, then you could parallel the DC outputs for more current, but you cannot mix out of phase AC voltages together

OK... That's answer I needs.... thankyou... And If That Isolation Transformer Secondary Is Always Same Voltage Is Parallely is Possible ?, maybe replace isolation transformer with voltage stabilizer transformer ?, and do you think is likely to phase - neutral voltage isn't always same ?, that transformer is only supply that building privately... also if I connected them parallely I think that load is always distributed in equal to these three transformer...

 

OK... That's answer I needs.... thankyou... And If That Isolation Transformer Secondary Is Always Same Voltage Is Parallely is Possible ?, maybe replace isolation transformer with voltage stabilizer transformer ?, and do you think is likely to phase - neutral voltage isn't always same ?, that transformer is only supply that building privately... also if I connected them parallely I think that load is always distributed in equal to these three transformer...

Is in this case I need's very instant voltage stabilizer ?, and can I change that configurations to Transformer 1 : R-S, Transformer 2 : S-T, Transformer 3 : R-T, do you think voltage in this configurations is always constant in 380v ?, and if yes... I can stepped down from 380v to 220v

 

Very wrong answer

No, my answer is right and yours is wrong.
But go ahead a try it and send us a picture of the pretty sparks and smoke.

 

No, my answer is right and yours is wrong.
But go ahead a try it and send us a picture of the pretty sparks and smoke.

Ha ha ha... Yes... I am wrong... But If I replace that isolation transformer with voltage stabilizer, so... output voltage is exactly same do you think I can connect that voltage stabilizer parallely with input is difference phase ?

 

Is in this case I need's very instant voltage stabilizer ?, and can I change that configurations to Transformer 1 : R-S, Transformer 2 : S-T, Transformer 3 : R-T, do you think voltage in this configurations is always constant in 380v ?, and if yes... I can stepped down from 380v to 220v

You must know that there are scores of transformers and voltage stabilizers already in the transmission system from the original point of energy generation to your mythical transformer configuration. None of them change the basic nature of the three-phase 120 degree offset rotational energy equation.

https://www.physicsforums.com/threa...hase-electric-power-setup.952380/post-6038218

 

You must know that there are scores of transformers and voltage stabilizers already in the transmission system from the original point of energy generation to your mythical transformer configuration. None of them change the basic nature of the three-phase 120 degree offset rotational energy equation.

https://www.physicsforums.com/threa...hase-electric-power-setup.952380/post-6038218

Can I change that energy rotation ?, or only way is convert them with three phase rectifier and use inverter ?, also I can use battery in middle to make big online UPS ?

 

Can I change that energy rotation ?, or only way is convert them with three phase rectifier and use inverter ?, also I can use battery in middle to make big online UPS ?

The first question would be why do you need the full three-phase AC power to single phase AC power conversion? The common thing is just to take two legs or a leg to neutral for a single phase power tap from a three-phase feed. Most direct AC utility devices that would need full three-phase AC power would be designed to use it directly.

This thread so far is theoretical with no actual requirements for anything practical.

 

The first question would be why do you need the full three-phase AC power to single phase AC power conversion? The common thing is just to take two legs or a leg to neutral for a single phase power tap from a three-phase feed. Most direct AC utility devices that would need full three-phase AC power would be designed to use it directly.

This thread so far is theoretical with no actual requirements for anything practical.

Very Practical !, I have 100kVA Chinese Voltage Stabilizer, But Single Phase Is Limited to 22kVA !, and It's Chinese Govenrment Regulation, So You Can't Change It !, Also Doesn't Assume This Is Common, and no Two Legs System in Chinese, All Three Phase is 4 Wire 220v/380v, and Single Phase is 2 Wire 220v, Nothing Like 120v like in US nor Canada !, YES It's Case Is Very Uncommon In North America !
Please answer my question, Can I change that energy rotation so I can use them as full one single phase with highest efficiency ?

 

Very Practical !, I have 100kVA Chinese Voltage Stabilizer, But Single Phase Is Limited to 22kVA !, and It's Chinese Govenrment Regulation, So You Can't Change It !, Also Doesn't Assume This Is Common, and no Two Legs System in Chinese, All Three Phase is 4 Wire 220v/380v, and Single Phase is 2 Wire 220v, Nothing Like 120v like in US nor Canada !, YES It's Case Is Very Uncommon In North America !
Please answer my question, Can I change that energy rotation so I can use them as full one single phase with highest efficiency ?

Of course I can use multiple meter with 22kVA 100a 220v Capacity, but there is supply by difference single phase transformer (25kVA, 24kV Primary, 220v Secondary) and also from difference rotation in 24kV/24000v MV Primary Side !

 

Of course I can use multiple meter with 22kVA 100a 220v Capacity, but there is supply by difference single phase transformer (25kVA, 24kV Primary, 220v Secondary) and also from difference rotation in 24kV/24000v MV Primary Side !

Also I can't use more than 2 smart meter in one buildings !, This Is Not Western Contries, Don't ever think that's is praticall or not, usual or not in your countries !, This Difference System with Difference Regulation, also with higher electricity theft than publicly available data !, of course higher electricity theft than US !, So Don't Think System Is Same With US !

 

Yes, you can change the relative phases, and even make them all the same but you need more than a transformer. You need an electrical converter.

Example: convert voltages to DC then use the DC to drive a motor-generator or am electronic DC to AC converter.

 

Very Practical !, I have 100kVA Chinese Voltage Stabilizer, But Single Phase Is Limited to 22kVA !, and It's Chinese Govenrment Regulation, So You Can't Change It !, Also Doesn't Assume This Is Common, and no Two Legs System in Chinese, All Three Phase is 4 Wire 220v/380v, and Single Phase is 2 Wire 220v, Nothing Like 120v like in US nor Canada !, YES It's Case Is Very Uncommon In North America !
Please answer my question, Can I change that energy rotation so I can use them as full one single phase with highest efficiency ?

I would get the proper 3-phase 100kVA Chinese Voltage Stabilizer and utilize the three-phase output to provide individual proper VA sized single phase connections to loads like most people do.

 

It's been a long time since I've done a load calculation, but that's how neutral conductors are sized. You figure your total continuous and non-continuous load as well as maximum unbalanced load and determine your minimum neutral conductor size off of that as described in the code book.

If I'm not mistaken, single phase residential services are permitted an automatic reduction of 83% or so from the size of the largest ungrounded conductor. The likelihood of pulling 83%+ of the service rating on a single leg of the service inside of a household is extremely unlikely. And even so, a 17% overload once in a blue moon isn't going to burn the building down.

EDIT:

I skipped. Whoops.

Sounds like OP needs a lesson in vector math. You can talk about different jurisdictions all day long but vector math applies universally. Connect two or three single phase transformers 120 degrees out of phase with each other in parallel and you'll get flames. If they're not perfectly in phase with each other there will be a difference in potential between their terminations at any given instant in time. If you need to power single phase loads from a three phase source, the only practical way of doing it is to distribute multiple single phase loads evenly from line to line or line to neutral.

 

Yes, you can change the relative phases, and even make them all the same but you need more than a transformer. You need an electrical converter.

Example: convert voltages to DC then use the DC to drive a motor-generator or am electronic DC to AC converter.

Yes.... I know but cost is very high in my area, is there any other reliable solution ?, give some advise please..., I was very frustated because this project is in Chinese Government area (PRC), so only local power supply is approved, and isn't really reliable and efficient, if is made by my team, I was worry to make three phase AC then covert to DC also to AC converter because capacity is very big, and reliability is a problem (with three phase rectifier and inverter, by these way I also can add power source from battery bank and solar panel)
What do you think about electrical converter ?, can I use 3 phase motor that rotate 1 phase motor, so that one phase motor generate 1 phase electricity, are you think this idea is reliable and efficient ?, space isn't really a big problem

 

It's been a long time since I've done a load calculation, but that's how neutral conductors are sized. You figure your total continuous and non-continuous load as well as maximum unbalanced load and determine your minimum neutral conductor size off of that as described in the code book.

If I'm not mistaken, single phase residential services are permitted an automatic reduction of 83% or so from the size of the largest ungrounded conductor. The likelihood of pulling 83%+ of the service rating on a single leg of the service inside of a household is extremely unlikely. And even so, a 17% overload once in a blue moon isn't going to burn the building down.

EDIT:

I skipped. Whoops.

Sounds like OP needs a lesson in vector math. You can talk about different jurisdictions all day long but vector math applies universally. Connect two or three single phase transformers 120 degrees out of phase with each other in parallel and you'll get flames. If they're not perfectly in phase with each other there will be a difference in potential between their terminations at any given instant in time. If you need to power single phase loads from a three phase source, the only practical way of doing it is to distribute multiple single phase loads evenly from line to line or line to neutral.

Ok Thanks... but I need larger one, not thinner, I was planned to use 70mm2 or 95mm2 neutral, where phase wire is 50mm2, because all load is single phase and it's likely to have harmonics problem, because majority load is data center and CNC machines

 

Motor-generator sets were popular in the early 1900s for conversion of AC to DC, etc. There's no reason one won't work if you really need to convert three phase to single phase. Be aware the investment cost will be high, efficiency will be low, maintenance will be required and the output will not be the most stable.

 

I can't help wondering why it needs to be converted to single phase for servers and CNC machines. (I'm assuming small CNC machines <1kW, as larger ones would already be 3-phase)
It seems like a large number of small loads so some could be on each phase to spread the load equally over the three phases.