Discussion of AC mains isolation transformers

[Middy]

Not often I see a bowling ball of great advice done in one go. Lovely to hear it's made a great improvement for you.

It give me hope of greater improvement is possible with big strides not ambiguous small changes.

Thanks for the great post

Dave

 

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[asdf1000]

Not often I see a bowling ball of great advice done in one go. Lovely to hear it's made a great improvement for you.

It give me hope of greater improvement is possible with big strides not ambiguous small changes.

Thanks for the great post

Dave

 

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Haha love the bowling ball call there Dave. I have to add, that no changes were made to my speakers and amp/DAC. It was all based around feeding my DAC the highest quality and lowest noise signal that I can currently afford lol. Enough with the upgrades for a few years now. I can finally relax and enjoy the music.

 

 

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[Middy]

Haha love the bowling ball call there Dave. I have to add, that no changes were made to my speakers and amp/DAC. It was all based around feeding my DAC the highest quality and lowest noise signal that I can currently afford lol. Enough with the upgrades for a few years now. I can finally relax and enjoy the music.

 

 

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I will miss you posting......The only way to stop upgrading is give all your money away to cat sanctuary or block your PC from reading Computer Audiophile.... Thanks though.. you have given me encouragement to get my isolation transformer.... I did order a cheap DC offset filter incase I get humming from the iso trans....Something to think about.[emoji15]

Regardless have fun and keep smiling...

Kind regards

Dave

 

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[asdf1000]

I will miss you posting......The only way to stop upgrading is give all your money away to cat sanctuary or block your PC from reading Computer Audiophile.... Thanks though.. you have given me encouragement to get my isolation transformer.... I did order a cheap DC offset filter incase I get humming from the iso trans....Something to think about.[emoji15]

Regardless have fun and keep smiling...

Kind regards

Dave

 

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I'll definitely be around. I hope to share my experiences and learnings from all the guru's I named and some incredibly clever members, with others! Otherwise what's the point, it's no fun unless you can help somebody else to bring out the best in their system. Having said that, I'll just be pointing to what all the experts said and the reasons they gave. I'm definitely no expert myself but I have enjoyed the learning in getting here.

 

I'll always be keeping an eye out for what those Uptone and Sonore and Roon lads cook up next. It's an exciting time in computer based audio and streaming. I can't believe it took me this long to get into it.

 

 

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[One and a half]

@Em2016

Very happy that the SQ has improved with AC cleaned up, the right way. Most noticeable is the black, the music just fades out into the deep.

 

My neglect, in previous posts about grounding one side of the output of the transformer. Familiarity leads to carelessness. Anyway, here's the corrected drawing of how the secondary of the isolation transformer should work in with the GFCI/RCD. As John Swenson points out, the reference needs to be known, and this is the earth/ground line.

 

 

There maybe more protection relays out there, the one I worked with is from Bender measures earth faults on ungrounded systems. The IR420-D4 relay sends out a pulse and measures the return. Ideally, there shouldn't be any return if the insulation systems are healthy. If there is a leak to ground, the return follows the path of least resistance back to the monitor where is raises alarms and if severe enough can disconnect the supply.

More application here.

 

The IR420-D4 is a fine relay for industrial systems, however the pulse that it sends out can end up in audio circuits, which we don't want, and the relay is about EUR500, so not a cheap purchase, plus adding a disconnection device, box, cables, so. Not recommended.

 

The purpose of the isolation transformer is to knock common mode noise from the AC line in your house which it does well. By adding the earth to one of the secondaries, not only reduces the common mode noise further, but allows the supply to be used safely (with a GFCI).

[asdf1000]

@Em2016

Very happy that the SQ has improved with AC cleaned up, the right way. Most noticeable is the black, the music just fades out into the deep.

 

My neglect, in previous posts about grounding one side of the output of the transformer. Familiarity leads to carelessness. Anyway, here's the corrected drawing of how the secondary of the isolation transformer should work in with the GFCI/RCD. As John Swenson points out, the reference needs to be known, and this is the earth/ground line.

 

[ATTACH=CONFIG]30927[/ATTACH]

 

There maybe more protection relays out there, the one I worked with is from Bender measures earth faults on ungrounded systems. The IR420-D4 relay sends out a pulse and measures the return. Ideally, there shouldn't be any return if the insulation systems are healthy. If there is a leak to ground, the return follows the path of least resistance back to the monitor where is raises alarms and if severe enough can disconnect the supply.

More application here.

 

The IR420-D4 is a fine relay for industrial systems, however the pulse that it sends out can end up in audio circuits, which we don't want, and the relay is about EUR500, so not a cheap purchase, plus adding a disconnection device, box, cables, so. Not recommended.

 

The purpose of the isolation transformer is to knock common mode noise from the AC line in your house which it does well. By adding the earth to one of the secondaries, not only reduces the common mode noise further, but allows the supply to be used safely (with a GFCI).

Thanks so much once again. For my Elgar, both the input and output earth pins are grounded to the transformer chassis. Also the shield windings are grounded on both the input and output windings. The output Active and Neutral are floating and are isolated from the mains input.

 

I've been using this twin-socket Clipsal portable RCD on the output of the Elgar as per your recommendation: Clipsal - 485P2CB30 - RCD Protected Twin Switch Socket Outlet, 250V, 10A, 30mA RCD, Electric Orange - it's essentially only wires along the full path anyway, no filtering or conditioning circuitry is added to the path.

 

But based on the above mentioned configuration for my Elgar, do you think the portable RCD on the Elgar's outlet is redundant?

[Middy]

superb ....Thanks One and a half

 

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[Cornan]

I will receive my Peaktech 2240 isolation transformer with floating secondary today. Here is an image how I intend to put it together:

 

Inputs are always welcomed!

Ps. I have a central GFCI installed in my appartment and have no intention to add a GFCI on the output of the transformer. Ds.

[One and a half]

Thanks so much once again. For my Elgar, both the input and output earth pins are grounded to the transformer chassis. Also the shield windings are grounded on both the input and output windings. The output Active and Neutral are floating and are isolated from the mains input.

 

I've been using this twin-socket Clipsal portable RCD on the output of the Elgar as per your recommendation: Clipsal - 485P2CB30 - RCD Protected Twin Switch Socket Outlet, 250V, 10A, 30mA RCD, Electric Orange - it's essentially only wires along the full path anyway, no filtering or conditioning circuitry is added to the path.

 

But based on the above mentioned configuration for my Elgar, do you think the portable RCD on the Elgar's outlet is redundant?

 

You need to connect the 'lower' side of the floating secondary to earth to make the RCD work. You only need one RCD in the whole system.

[asdf1000]

You need to connect the 'lower' side of the floating secondary to earth to make the RCD work. You only need one RCD in the whole system.

Ok thanks. In this case the portable RCD stays on the output for my Elgar. It's not expensive considering it may save my life one day, if it functions properly.

 

And with no filtering and conditioning circuitry (our aim here) being added to the path I can't see how it would be detrimental to sound quality / performance.

 

For anyone thinking of adding a portable RCD to their system like mine, I would go with one like the twin socket linked above, which has the safety switch that flips up and down for on/off. I tried the single outlet portable RCD (plug in adaptor) with LED indicator for on/off and found the LED light to be so faint and not reliable, so not the safest.

 

It stays hidden along with the iso transformer too, so there's no visuals to worry about.

[tapatrick]

Thanks for your post John.

 

Indeed a true isolation transformer is quite safe. In fact, before there were GFCIs, hotels used to have "shaver-only" outlets which contained--you guessed it, a small isolation transformer.

 

But it turns out that many (likely most) of the in-a-case with outlets units presently sold as "isolation transformers" in fact are not. Due to NEC (and probably EU) requirements--along with a desire for even greater common-mode noise attenuation--they are most all bonding one leg of the secondary to ground. This of course defeats the safety aspects of a "floating secondary" as John describes above.

 

Again, I am not talking about just running the input ground to the chassis and through to the third pin of the output outlets. I am saying that the TrippLites, the Eatons, and many others are connecting one side of the secondary to ground! That is why there are lots of videos by techs and old radio repair guys showing people how to "re-float" their TrippLite "isolation" trans units--since that is important for safety for those folks.

 

Of course the old stock industrial Topaz units are not doing this (though if I bought one prewired with cord and outlets I would check it).

 

And perhaps the "grounded neutral secondary" pseudo isolation units offered to the public these days would indeed benefit from a GFCI.

 

Here is a page from the current Eaton "Power Suppress" series (you can see the secondary being grounded), and all the TrippLite "Isolator Series" pages state "Secondary Neutral Bonding."

 

[ATTACH=CONFIG]30782[/ATTACH]

 

 

This is a top thread and appreciate all the input.

 

I have a question as I'm thinking to pick up a Topaz at some point. In relationship to floating and/or connected to secondary grounds - I would appreciate if someone can explain from the diagram what the S1 and S2 wiring and the chassis to core wiring are achieving.

 

 

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[tapatrick]

[ATTACH]30932[/ATTACH]

 

This is a top thread and appreciate all the input.

 

I have a question as I'm thinking to pick up a Topaz at some point. In relationship to floating and/or connected to secondary grounds - I would appreciate if someone can explain from the diagram what the S1 and S2 wiring and the chassis to core wiring are achieving.

 

 

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Okay there doesn't seem to be any comments to my question on Isolation transformer wiring. I understand the core connects to chassis therefore to the ground but does anyone know why the shields ( S1 & 2 ) would connect to the neutrals?

 

Thanks in advance!

 

 

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[Cornan]

Okay there doesn't seem to be any comments to my question on Isolation transformer wiring. I understand the core connects to chassis therefore to the ground but does anyone know why the shields ( S1 & 2 ) would connect to the neutrals?

 

Thanks in advance!

 

 

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Hmmm...I wonder if the shields are there to prevent the chassi to be electrified in case a fuse blow? AFAIK if a fuse blow the neutral will become hot (but still safe on a IT with floating secondary due to the chassi ground (and perhaps the additional shielding)..but could be potentially dangerous on a old or bad contructed type of IT w/grounded secondary. Just a "qualified" guess though...

 

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[Middy]

Sorry tapatrick ..I wouldn't know where to start.....

 

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[tapatrick]

Thanks Cornan & Middy.

 

 

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[Middy]

I found these with a simple search but I think if you have to question any part of wiring anything electrical then pro help is a minimum. Do the company who made these still exist in some form? They should have a tech help department.. with people asking this all the time....Even some surplus suppliers must have manuals wiring diagrams.

You can't complain about bad sound if your dead..... Be safe? and good luck

 

 

https://forum.audiogon.com/discussions/wiring-an-isolation-transformer

 

http://www.diyaudio.com/forums/power-supplies/104346-please-help-isolation-balanced-power-question-2.html

 

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[asdf1000]

Just wondering if the next logical step is an ultracap power supply (with switching banks like the LPS-1) capable of 2400W output continuously (or even half that) to power our amps and take them off the grid.

 

I know it would be massive in size (in comparison to the LPS-1) but it would kill the need for these old iso transformers or newer and very expensive power regenerators and power conditioners.

 

It seems like the next logical but very significant step now... Has to be a matter of time (and cost) before one comes out.

 

I may be missing something else which would be holding this back, which I didn't consider. Apologies in advance if I have.

 

Regulatory approvals for anything outputting AC power would be a pain to go through, especially for a small boutique company, and especially if attempting to do so on a global scale.

 

I know there are amps out there or being worked on that feature these banks of switching ultracaps, so this is more about something that the user could use with their existing gear. Essentially it would be a PS Audio Power Plant 10 but disconnected from the mains and hopefully cheaper lol

[Cornan]

Just wondering if the next logical step is an ultracap power supply (with switching banks like the LPS-1) capable of 2400W output continuously (or even half that) to power our amps and take them off the grid.

 

I know it would be massive in size (in comparison to the LPS-1) but it would kill the need for these old iso transformers or newer and very expensive power regenerators and power conditioners.

 

It seems like the next logical but very significant step now... Has to be a matter of time (and cost) before one comes out.

 

I may be missing something else which would be holding this back, which I didn't consider. Apologies in advance if I have.

 

Regulatory approvals for anything outputting AC power would be a pain to go through, especially for a small boutique company, and especially if attempting to do so on a global scale.

 

I know there are amps out there or being worked on that feature these banks of switching ultracaps, so this is more about something that the user could use with their existing gear. Essentially it would be a PS Audio Power Plant 10 but disconnected from the mains and hopefully cheaper lol

I share your dream...but remember that JS recomends iso transformers w/floating secondary for the LPS-1 as well...just because it still is sensitive to leakage loops. Also Vinnie Rossie custom LIO http://www.vinnierossi.com/configure-lio/ already is a integrated amp which have built in ultracapacitor power supply with additional output power to supply the microRendu. I would love to own that amp!

Anyway, ultracapacitor supply do not remove the needs for ITs just yet...but with the LIO custom it is pretty darn close.

 

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[asdf1000]

I share your dream...but remember that JS recomends iso transformers w/floating secondary for the LPS-1 as well...just because it still is sensitive to leakage loops. Also Vinnie Rossie custom LIO Configure LIO - Your Personal High-End Audio System already is a integrated amp which have built in ultracapacitor power supply with additional output power to supply the microRendu. I would love to own that amp!

Anyway, ultracapacitor supply do not remove the needs for ITs just yet.

 

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Hi Cornan, yes my last paragraph was hinting at the Vinnie but I didn't want to mention it in this Uptone thread :-)

 

I hadn't seen the recommendation for an iso transformer with the LPS-1 specifically but may have missed it. I thought it was more about the entire system plugging into one iso transformer, on a powerstrip with no filtering or conditioning circuitry.

 

I agree the iso transformer still stays but it might be redundant if a PS Audio P10 type ultracap (with switching banks) unit were able to 'isolate' from the mains.

 

Since the PS Audio P10 has as lot of filtering and conditioning circuitry I should re-word what I said earlier. This kind of AC ultracap power supply would be a P10 but isolated from the mains at all times (via swiching ultracap banks) and have only wiring between all AC outlets (and again, hopefully a much lower price). I think the recommendation has to be to continue to use the iso transformer because such a product doesn't exist yet ! And perhaps never will.

 

Anyway, just a pipe dream on my part, as you say lol :-)

 

Until then we continue to enjoy the music !

[One and a half]

Okay there doesn't seem to be any comments to my question on Isolation transformer wiring. I understand the core connects to chassis therefore to the ground but does anyone know why the shields ( S1 & 2 ) would connect to the neutrals?

 

Thanks in advance!

 

The S1 and S2 are shields. Depending on the source which could come from a UPS PV inverter or a generator, H4 can be connected to ground. It's a convenience thing.

 

For USA: [standard house wiring]

 

Input

120V ac Hot -> H1 + H3

 

120V Neutral --> H2 + H4

 

Ground from 120V --> S1 + Chassis (remove the link H4-S1)

 

Output

120V ac Hot Sec --> X1 + X3

 

120V Neutral Sec --> X2 + X4

 

S2 --> chassis

 

Output Ground --> Chassis + X4 (retain link X4-S2)

 

For EU/AU

 

H3+H2

230V hot --> H1

230V neutral --> H4 (remove the link H4-S1)

Ground from 230V --> S1 + Chassis

 

Output

X3+X2

230V hot --> X1

230V Neutral X4 + S2 + Chassis

 

For balanced output 115-0-115

Output

X2+X3 + chassis

 

Remove X4 to S2

 

S2 to chassis + X2

 

In all cases, use a GFCI or RCD on the output. Grounding the secondary keeps the potential of the chassis voltages of the equipment at the one low level. Floating the secondary elevates them, why would you do that?

[asdf1000]

I don't know what happened but compared to yesterday and days prior the sound just got even smoother but not at all less detailed. No idea if the LPS-1 or DC-4 power cable or iso transformer or Curious USB cable (or any combination of these) needed time to settle. The only time I noticed something like this was when I purchased a pair of KEF LS50's a few years ago and after a week or so there was a sudden opening up to the sound. But that was speakers and moving parts. I can't really explain this though. But I like it...

[Cornan]

I don't know what happened but compared to yesterday and days prior the sound just got even smoother but not at all less detailed. No idea if the LPS-1 or DC-4 power cable or iso transformer or Curious USB cable (or any combination of these) needed time to settle. The only time I noticed something like this was when I purchased a pair of KEF LS50's a few years ago and after a week or so there was a sudden opening up to the sound. But that was speakers and moving parts. I can't really explain this though. But I like it...

 

I have noticed the same thing with my Peaktech 2240 in my setup. I guess a new IT needs little "burn-in" or "settle-in" or "time-to-do-its-thing"!

[Cornan]

In all cases, use a GFCI or RCD on the output. Grounding the secondary keeps the potential of the chassis voltages of the equipment at the one low level. Floating the secondary elevates them, why would you do that?

Just thought of one thing regarding this statement. I am using Entreq Minimus to ground the chassi of my DAC which is connected to my Peaktech 2240 iso transformator w/floating secondary. As far as I can see it is a good thing. Maybe I should actually connect a Minimus to the chassi of my Peaktech as well? I will surely ask Entreq about this matter...but what is your opinion about it? A good or really bad idea?

[Cornan]

I hadn't seen the recommendation for an iso transformer with the LPS-1 specifically but may have missed it. I thought it was more about the entire system plugging into one iso transformer, on a powerstrip with no filtering or conditioning circuitry.

 

I have´nt seen it either...but his recommendations includes the LPS-1 since it should also be plugged into the same unfiltered power strip connected to a IT w/floating secondary....and not to be treated differently AFAIK. If it was totally immune against leakage currents it would be fine to plug it in anywere. But that is...hrmm...my personal analyze of his suggestions ofcourse! :-)

[asdf1000]

I have´nt seen it either...but his recommendations includes the LPS-1 since it should also be plugged into the same unfiltered power strip connected to a IT w/floating secondary....and not to be treated differently AFAIK. If it was totally immune against leakage currents it would be fine to plug it in anywere. But that is...hrmm...my personal analyze of his suggestions ofcourse! :-)

Oh yes, I think John S recommended plugging a power strip (with no filtering or conditioning circuitry between outlets) into an iso transformer (with extremely low inter-winding capacitance) and have all your HiFi devices (not only the LPS-1) into the one power strip - if all that's possible of course. I may have misunderstood though, so apologies in advance if I did.

 

So in my pipe dream ultracaps power supply product, the iso transformer and power strip would be replaced by this P10 type thing, as long as all outlets again had no filtering between them (to keep leakage currents as low as possible). But again, this product doesn't exist, so of course the iso transformer solution discussed in this entire thread remains the best solution.

 

I was just thinking where else things may go with ultracaps switching-banks type products. Apologies for diverting from the topic of the thread (although it is remotely still about isolation from mains power).