50Hz transformer experts?

[kridri]

Maybe you can connect two common used transformers back to back so 400V/15kV and 15kV to 400kV.
But with the second transformer with his own 'regulator' so you can crank up the voltage a little bit to 460V.

[oldway]

Are there any 50Hz transformer experts loitering around here??

I need the smallest possible (within practical limits) 150kW 400:460 Vac 3 phase stepup isolating transformer!! I think it'll need to be ODWF in order to get the power density up high enough.  I have a source of cooling water at 5degC (and -30 degC if things get really serious....) which ought to help.

Anyone have any experience with such a device?? 

Maybe you can connect two common used transformers back to back so 400V/15kV and 15kV to 400kV.
But with the second transformer with his own 'regulator' so you can crank up the voltage a little bit to 460V.

In the reduced space where one transformer hardly fit, for sure, two will NEVER fit ....

[mc172]

They might if you stack them.

[oldway]

They might if you stack them.

How could you stack two transformers when the problem is to fit one in the available space ?

[mc172]

Well, that would be "to fit within the same available volume", wouldn't it.

[oldway]

My mother language is french, you are only making fun of google translation, that's not a very clever attitude. 

[Zero999]

My mother language is french, you are only making fun of google translation, that's not a very clever attitude. 

I agree. It's silly. I knew what you meant. It's common sense. Two transformers will take up more space, than a single one and the chief requirement was for it to be as small as possible.

Unfortunately no dimensions were given by the original poster. There's also a limit to small a 50Hz transformer, of a certain power rating, can be, due to physics. One way round this would be to chop the input voltage to a higher frequency, pass it through a smaller, high frequency transformer, then rectify it and pass it through an inverter and filter to get it back to 50Hz.

[oldway]

As is often the case on this forum, max_torque does not provide the information needed to be able to provide a solution to its problem.

Already and to begin with, we NEVER specify the power of a transformer 50Hz in KW's but only in KVA's, demonstrating that max_torque does not even know the most basic concepts in transformers design

So, he should give us all the information possible because with the little information he gives us, we are obliged to guess.
That's not the way I like to work. I need technical data and specifications.

1) The power of 150KW? Where does this value come from? We can guess that this transformer will be used to power a power supply of 150KW and that the load is probably a three-phase rectifier bridge.
The power is then certainly much higher than 150KVA's.
How many ? A measurement of the RMS current per phase made on the current 330KVA's transformer with full load of the 150KW power supply would be very useful.

2) the volume available? What forms and dimensions? A drawing would be welcome. Where is this volume? In the 150KW power supply cabinet? Does this cabinet have forced ventilation? Is it possible to install forced ventilation in the available volume?

3) the operating conditions of the transformer? Max_torque has already given some explanations, but it would be necessary to be more precise on the most demanding conditions.

4) What's the maximum mains voltage possible ?

NB: If you are not satisfied with my bad english, thank you for complaining to google translation.
I only assume the technical point of view of my posts.

[mc172]

My mother language is french, you are only making fun of google translation, that's not a very clever attitude. 

What a retarded comment. I wasn't making fun of your English, I was saying that if he absolutely had to fit it in the same volume he'd have said "to fit within the same volume". Most of the time people are concerned about floor area, not the volume of air above the device, which is largely unused.

If you're using and relying on Google Translate, how do you know to use the term "an" in front of "HP1740A" in other posts?

[oldway]

In french, people say : le transformateur doit pouvoir être placé dans l'espace disponible, so I did not feel nothing wrong with translation of Google ....

I read fluently tecnical english but this does not means that I speak and write also fluently english.
I learned english at school many years ago and I still remember of some tips, but not enough to write without help of Google translation.

I used an in front of HP1740A because I read this in technical papers, that does not proove nothing about my knowledge of english.

When people say : I need the smallest possible (within practical limits) 150kW 400:460 Vac 3 phase stepup isolating transformer!!, that means that ALL the dimensions must be the smallest possible, the height too. No floor area here... !

If there is one post in this topic who his a retarded comment, it is well your post...

[oldway]

And still another solution of the problem: an external three phase frequency converter 50Hz - 400Hz 200KVA's and a 400Hz three phase isolating transformer who will fit for sure in the little volume available.

http://www.mak-powersis.de/200-kva-frequency-converter.html

[Jeroen3]

You would need to ask companies that wind them at customer request. Like Belpa or Drie Transfomatoren.
But if it is to make DC, a plain 50 hz one might not be the best option. You can get them with phases offset to get more pulses.
You could also check if a 400 Hz rotary converter fits the space.

[Zero999]

You would need to ask companies that wind them at customer request. Like Belpa or Drie Transfomatoren.
But if it is to make DC, a plain 50 hz one might not be the best option. You can get them with phases offset to get more pulses.
You could also check if a 400 Hz rotary converter fits the space.

Who said anything about a rotary converter? That's not how it's done these days! An inverter, consisting of IGBTs, is used to increase the frequency. I wouldn't recommend 400Hz. I'd go as high as is practical before the skin effect becomes a significant factor.

[Jeroen3]

Think outside the box. Isolated supply was requested for high power low voltage DC.
Apparently there are space constraints. With a rotary converter you have a different space footprint than transformer.

Also, big chunks of copper are less destructible then anything with semiconductors.

[oldway]

Cost doesn't matter, and  no, i'm not making it myself!

I'm trying to establish if there is a hope-in-hell of fitting an isolation transformer into an existing bit of kit (a 150kW DC supply).  It's currently connected to a 330kVA iso xformer, which is, as you would expect massive!

It certainly doesn't need to be continuously rated, say 70% continuous and a max of 3min at peak power.  It is going in a 'smart' system, so we can monitor temps / currents or what ever for safeguarding etc

The package space i have is under 50% of the size of the current 330kVA unit, so i need to push the limits somewhat, both in terms of winding I2R losses (oil to water cooling) but also probably in terms of core saturation (take a reduction in efficiency, as i have effectively an infinite supply to drive it from)

For me, what max_torque wants to do is clear.
He wants to remove the current transformer of 330Kva that is outside the 150KW power supply (probably to save space) and replace it with a transformer placed inside the cabinet of the 150KW power supply.
The volume available in this cabinet is 50% that of the current transformer of 330KVA's.

Therefore, any solution proposal with equipment placed outside of the cabinet is of no interest.

In summary, to solve this problem, we need to:

1) Measure the RMS line current of the 330KVA transformer with the fully loaded power supply to determine the maximum power in KVA's actually consumed.

2) determine the maximum conditions of use. (Load x duration)

3) check whether forced ventilation is possible or not (depends on the 150KW power supply cabinet, we have no details about it ... what brand, what model?) If possible, what's the cold air max temperature ?

4) it is necessary to have a drawing of the available volume with the max. dimensions.

5) What are the network voltage specifications?

6 ) What is the load of the transformer? Bridge rectifier? What kind of filtering? Head Capacitor or head Inductor?

7) what are the acceptable variations of the secondary voltage at idle / full load?

8 ) What are the characteristics of the current 330 KVA's transformer? (Copy or picture of transformer nameplate.)

9) Pictures of the 150KW power supply, with door of the cabinet open.