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Isolation Transformer?

Discussion in 'Power Electronics' started by SailingHome, Jul 4, 2019.

  1. SailingHome

    SailingHome

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    Jul 4, 2019
    Why am I finding it impossible to find a simple isolation transformer 220v 50Hz mains to 220v 50Hz leads? IE ISOLATE and protect from reaching ground.
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    Probably because they are rarely used these day, the exception being operating rooms but they are rather different from the everyday one to one units from the past.

    Safety cut, safety switch, earth leakage circuit breakers, all the same thing, are the normal piece of gear these days.
    Usual to have them installed on the switchboard in dwellings.
    There are also portable units with 2 double pole outlets.
    Depends which country you come from however and example of ones in use in Australia are shown attached.
     

    Attached Files:

  3. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Maybe you are looking in all the wrong places. Try visiting some of the sites that this Google results page brings up. It might help if you told us where (in the world) you are located. You will also need to provide some more specifications for your isolation transformer. Things like VA capacity, isolation resistance, isolation capacitance, etc.
     
  4. SailingHome

    SailingHome

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    Jul 4, 2019
    Thanks, men,

    It's been a long time since my BA in electrical engineering... I must have been reading old data.

    I need to make either a 220VDC 15A supply or 17VDC 2kw supply in Thailand.

    Thoughts? It we really be nice to not hvae to hand wrap transformers =)
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Apart from the electrostatic shield and the optional earth passthrough, what else?
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    As far as the transformer is concerned, more than likely exactly the same.
    One difference could be the weight of these mothers. Another would be the cost involved.
    Couple of different sizes, I think it was 3.6kva,4.8kva and 7.2kva.
    I was referring to the monitoring used in conjunction with the line isolation used.
     

    Attached Files:

  7. Bluejets

    Bluejets

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    Oct 5, 2014
    No idea what this is supposed to mean.

    Why not simply use what in Thailand they call a "safety cut".??
     
  8. Martaine2005

    Martaine2005

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    May 12, 2015
    I personally use the ‘ITV-15 isolation transformer’.
    I would have thought an isolation transformer would be in everybodys lab or bench.

    Martin
     
  9. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    I was in my thirties before I went to work for an employer enlightened enough to see the value of an isolation transformer on my lab bench. Before then, I used two 6.3 VAC filament windings connected back-to-back on a pair of discarded TV transformers to obtain galvanic isolation on my lab bench at home. TV transformers are hard to find nowadays, what with everything being solid state and without power transformers, except for their SMPS circuits. Real isolation transformers, with a Faraday shield between windings, are still too pricey for me.
     
    Martaine2005 likes this.
  10. SailingHome

    SailingHome

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    Jul 4, 2019
    A safety cut would protect the circuit? For instance, I could use one, rectify and ripple filter the high voltage, and be safe?
     
  11. Martaine2005

    Martaine2005

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    Do you mean rectify AC to DC and smooth the ripple voltage?, This is still high voltage. So no, it's not safe to play with.
    Can you explain what you mean by this?
    We have gone off track from your first question about isolation. Any two 'walwart' transformers wired back to back will give isolation. But obviously depends on your power requirements.
    Please tell us what you are intending to do.

    @Bluejets has already mentioned the usual safety devices in consumer units. And there are many more not mentioned.

    Martin
     
  12. SailingHome

    SailingHome

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    Jul 4, 2019
    Well, I got kicked off e other forums for asking questions about not having an isolation transformer, so… I tried here.

    Martin, can we email on the site? if we are off track, we shouldn't bother others.

    In short, we need a huge amount of power for cooling server farms by using TEC units. The units self regulate current. In this case, the unit I want to test is 17VDC 15A. So, I am perfectly happy having a close enough voltage by put in series, or have a supply of 17VDC at 3kw+
     
  13. Martaine2005

    Martaine2005

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    https://en.wikipedia.org/wiki/Server_farm
    Is this what you mean?
    Sorry, we can't email on this site. It's beneficial for all to read and respond.
    So bothering others is not an issue.
    Ok, 3 x 6 Volt batteries in series is close enough (18v). Your 2Kv might be a problem though.

    Let me ask you a serious question.
    Are you trying to run a computer call centre?

    Martin
     
  14. SailingHome

    SailingHome

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    Jul 4, 2019
    No, no. I should be clear. I am a scientist and have a geant to cool a datacenter for Microsoft.
     
  15. Martaine2005

    Martaine2005

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    OK, sounds legitimate.
    Microsoft can supply your required equipment.. Call them, they will supply and give you a 3 year guarantee for $199.
    Or call me and I will give a 5 year guarantee for £399.
    India started this, Pakistan got the blame. Now Thailand wants some!, Then the Phillipines will get the blame?
    That is probably why other forums kicked you off..

    Martin
     
  16. SailingHome

    SailingHome

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    Jul 4, 2019
    Ummm… Martin? You just confused me to all ends of the earth.

    Yes, I do have a budget. I just want to know what to do. I am no stranger to high voltage. In Thailand the #1 cause of death is bad electric install. I made my building install <gasp> a ground wire! Took away the shocks, but leakage is still bad for high meter bills.

    I guess I don't get why I can't take a 30 breaker from mains, rectify it, ripple smooth it, set up a series of high ohm resisters sich that across each one would be near 17v, enclose it with an earth ground, and expose the 17v terminals.

    I truly do not want to build a 220 to 17v transformer for high current. I don't know enough to design a switching PSU of 1kW each.

    I can't change to the TEC1-12706 which I could use standard 12vdc power supplies because the space requires a certain wattage removed per sq cm.

    If I didn't have these grouops, I would do as above and not feel too worried, but this is a commercial outcome eventually.

    So, what ia it that can be supplied? Pigtailed isolation transformers?
     
  17. Bluejets

    Bluejets

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    Oct 5, 2014
    There are ways to do this and many in Thailand get it wrong.
    Thailand is an MEN earthing system but very few ever install it correctly which is why there are problems.
    Chucking an earth rod in the ground and connecting everything to it in a higldy pigldy fashion is not the answer.
    So next best solution is a safety switch or as they say there, a safety cut.More is better, i.e. one for each final sub-circuit as is the best arrangement.
    Many and varied sizes and breaker type are available to suit differing installs but the key is knowing which.
    Best not to join the "many" who go down the tube and get yourself a qualified electrician.
    Difficult to find there but they do exist, I have seen it.
    BTW...leakage has nothing to do with meter readings.
     
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Wow. No wonder you got booted from other sites.

    Do you want us to explain why that's not a realistic option, or will you just believe us?

    Apart from the fact that I find your story rather unbelievable, I am worried that your skill level is far too low to be considering this.

    My strongest recommendation is that you hire someone with real experience in this area.
     
    Tha fios agaibh and hevans1944 like this.
  19. hevans1944

    hevans1944 Hop - AC8NS

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    And to prevent propagating further misunderstanding, could we just close this thread without banning @SailingHome at this time? Mebbe later, 'cause I don't think he is one of us... Need to see some more dialog from him in a new thread to be sure.
     
  20. SailingHome

    SailingHome

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    Jul 4, 2019
    I will believe, yes. Keep in mind this is Thailand so the isolation needs to comply
     
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