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Author Topic: 3 Phase 200 Amp Isolated Audio Transformer  (Read 16019 times)

Peter Morris

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #10 on: July 04, 2011, 02:15:59 am »


I haven’t tried this  -  but a ferro resonant transformer may help – I have seen them on ebay quite cheap from time to time.  They are probably listed under voltage regulator transformers …

http://www.ustpower.com/Support/Voltage_Regulator_Comparison/Ferroresonant_Transformer_CVT.aspx


Hi Peter-

Your post got me to thinking about the electrical service installed at a State Park pavilion... the service labeled "Entertainment" is on a 35 KVA ferro-resonant transformer.  All the other power is right off the step-down 480/240v transformer.  Next time I'm out there, I'll take another look and talk to the park electrician for more details, but I recall it was installed because the service was "noisy".

Thanks for the memory jog.

Tim Mc

Soo … it’s not just me that had that thought …. thanks

As you would know, one of the things that a ferro-resonant transformer does in addition to maintain a constant voltage is act as a low-pass filter, effectively removing transient and surge voltages.

The energy stored in the transformer and associated circuit allows the output to "ride through" brief input power interruptions.
« Last Edit: July 04, 2011, 09:14:29 am by Peter Morris »
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Jeff Robinson

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #11 on: July 05, 2011, 12:23:08 am »

Soo … it’s not just me that had that thought …. thanks

As you would know, one of the things that a ferro-resonant transformer does in addition to maintain a constant voltage is act as a low-pass filter, effectively removing transient and surge voltages.

The energy stored in the transformer and associated circuit allows the output to "ride through" brief input power interruptions.

Ferro-resonant transformers add distortion to the ac waveform. They also really do not like to exceed their rated kva, ever. You do not want your gear hooked up if the capacitor in the tank circuit ever fails.

12.5kHz may be a beat frequency of the real carrier frequency. If it is above a few mHz a shielded power transformer could help (they generally have 20+dB noise reduction), also called a Faraday shield. This is a standard feature of Acme brand and an option in other brands.

There are power line filters in several brands also, available in a range of amperage ratings. MTE likely has some listed on their website.

HTH

Jeff Robinson
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Jim McKeveny

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #12 on: July 05, 2011, 10:09:26 am »

I must echo some of the previous posters comments: I have seen "engineers" demand iso transformers when the issues were much simpler/cheaper to remedy. There may indeed be some global junk in the power, but for it to be substantial enough to upset lots of gear downstream....rare.
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Greg Longtin

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #13 on: July 05, 2011, 01:42:40 pm »

Tom,

a series of 12.5k hertz "rings" through FOH & monitors

That transformer will be rather expensive.  Have you tried all other possible solutions?  You mentioned 'FOH & monitors', in what other equipment earlier in the signal chain do the 'rings' exist?

IOW, rather than add filtering/conditioning for the *whole* rig, just fix the offending pieces.

Some possible solutions are line level iso transformers, grounding and/or shielding changes, SurgeX, JuiceGoose, AC filtering, etc.  At one point Corcom made a very good 20 amp three phase line filter.  We used it for all line level monitor gear.

Greg
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Charlie Zureki

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #14 on: July 05, 2011, 02:52:45 pm »

Tom,

That transformer will be rather expensive.  Have you tried all other possible solutions?  You mentioned 'FOH & monitors', in what other equipment earlier in the signal chain do the 'rings' exist?

IOW, rather than add filtering/conditioning for the *whole* rig, just fix the offending pieces.

Some possible solutions are line level iso transformers, grounding and/or shielding changes, SurgeX, JuiceGoose, AC filtering, etc.  At one point Corcom made a very good 20 amp three phase line filter.  We used it for all line level monitor gear.

Greg

   Hello,

   If there is a 12.5k hertz signal superimposed on the line power, line level transformers, surgeX, and juicegoose devices will not filter it out.

  More than likely, the 12.5k signal is getting into the system through the Amplifiers and not as much through the console or processing gear. 

  Hammer
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Charlie Zureki

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #15 on: July 05, 2011, 03:02:30 pm »

Soo … it’s not just me that had that thought …. thanks

As you would know, one of the things that a ferro-resonant transformer does in addition to maintain a constant voltage is act as a low-pass filter, effectively removing transient and surge voltages.

The energy stored in the transformer and associated circuit allows the output to "ride through" brief input power interruptions.

Ferro-resonant transformers add distortion to the ac waveform. They also really do not like to exceed their rated kva, ever. You do not want your gear hooked up if the capacitor in the tank circuit ever fails.

12.5kHz may be a beat frequency of the real carrier frequency. If it is above a few mHz a shielded power transformer could help (they generally have 20+dB noise reduction), also called a Faraday shield. This is a standard feature of Acme brand and an option in other brands.

There are power line filters in several brands also, available in a range of amperage ratings. MTE likely has some listed on their website.

HTH

Jeff Robinson


  Hello,

   It is not a "beat frequency" , and a shielded transformer has nothing to do with the 12.5k signal that the Power Company injected into the power grid.

  Hammer
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Greg Longtin

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #16 on: July 05, 2011, 06:50:12 pm »

Charlie,

If there is a 12.5k hertz signal superimposed on the line power, line level transformers, surgeX, and juicegoose devices will not filter it out.

  More than likely, the 12.5k signal is getting into the system through the Amplifiers and not as much through the console or processing gear.

1. SurgeX & JuiceGoose make many units that are both suppressors *and* filters.  Can't run racks of amps with them, but it may not be the amps.

2. I've come across equipment with poor hi-freq common rejection, so line level transformers *may* help, depending on where the noise is entering the system.

3. High frequency line noise is caused by all sorts of equipment, this isn't a unique problem.

Greg
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Charlie Zureki

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #17 on: July 05, 2011, 09:19:45 pm »

Charlie,

If there is a 12.5k hertz signal superimposed on the line power, line level transformers, surgeX, and juicegoose devices will not filter it out.

  More than likely, the 12.5k signal is getting into the system through the Amplifiers and not as much through the console or processing gear.

1. SurgeX & JuiceGoose make many units that are both suppressors *and* filters.  Can't run racks of amps with them, but it may not be the amps.

2. I've come across equipment with poor hi-freq common rejection, so line level transformers *may* help, depending on where the noise is entering the system.

3. High frequency line noise is caused by all sorts of equipment, this isn't a unique problem.

Greg

   Hello,
      Surgex, Juice goose and etc...  work fairly well for current surge supression  and voltage spike protection. And, some of their advanced models will even out the current draws and help with voltage regulation ... keeping the output voltage within some spec established by the manufacturer...

   The filtering capabilities are only in regards to the unit's operation.

   These devices will not filter out a 12.5k sine wave that was added by the power utility.  Transformers pass Ac sinewaves they do not filter them out.

   While noise on power lines are a common problem... all electronic and electrical equipment that uses AC power sold in the U.S. is subject to standards written by the F.C.C.,..... in regards to outputting "noise" on the Electrical grid,  IEC, IEEE as well as F.C.C. for EFI and EMI  regulation.

  Hammer
     
« Last Edit: July 05, 2011, 10:05:38 pm by Charlie Zureki »
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Peter Morris

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #18 on: July 05, 2011, 09:40:41 pm »

Ferro-resonant transformers add distortion to the ac waveform. They also really do not like to exceed their rated kva, ever. You do not want your gear hooked up if the capacitor in the tank circuit ever fails.

12.5kHz may be a beat frequency of the real carrier frequency. If it is above a few mHz a shielded power transformer could help (they generally have 20+dB noise reduction), also called a Faraday shield. This is a standard feature of Acme brand and an option in other brands.

There are power line filters in several brands also, available in a range of amperage ratings. MTE likely has some listed on their website.

HTH

Jeff Robinson

In a past life, I often used the approach you mentioned in industrial situations to protect PLC’s from noise - 1:1 transformer, Faraday shield and LC filtering. From memory, this approach tended not to be that effective at lower frequencies like 12K5, that’s assuming it’s a fundamental, which as you noted, it may not be.

FWIW as I understand, the frequency of powerline communication systems can be as low 12K, usually higher... but not in the MHz region.

I must confess I have only played with Ferro’s briefly as implied in my first post. I was aware of the wave form issues but I believe modern designs are probably OK – 5% distortion for those optimized for sin wave outputs. I do not know how well they would work in this application but as I understand, they would be more effective at the lower frequencies than the approach described above.   Manufactures claim one of their applications is as a “line conditioners to protect computers and other sensitive electronic devices from transients, noise, and surges on the power line.”

http://www.generaltransformer.com/transformer/ferroresonant-transformers.htm
http://www.foster-transformer.com/Transformers/FerroresonantTransformers.aspx 
http://www.icrepq.com/icrepq07/317-valverde.pdf
http://powerqualityworld.blogspot.com/2011/04/constant-voltage-ferroresonant.html


Peter
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tomfabjance

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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #19 on: July 28, 2011, 05:54:40 pm »

What does your utility company say?

The electric company has acknowledged the problem and has taken suit with the manufacturer of the new technology.  Nobody has found a solution thus far other than shutting it off when I call every week.  They claim to have engineers investigating, looking for a fix
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Re: 3 Phase 200 Amp Isolated Audio Transformer
« Reply #19 on: July 28, 2011, 05:54:40 pm »


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