Home AC circuit dog fence interference

Discussion in 'General Electronics Chat' started by Gavindale, Jan 2, 2012.

  1. Gavindale

    Thread Starter New Member

    Jan 2, 2012
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    Hello all!
    I am finishing construction of a new recording studio facility. I have a 400 amp residential service with a new 200 amp breaker box in the new building.
    We use a electric underground dog fence and the unit that feeds the wire emits a pulsating noise on my building circuits.
    When any amplifier is energized the pulse is very clearly produced. This is bad enough but if this is transferred to the recording system then I have a disaster on my hand.
    My background is that of a electrical distribution lineman and I wired this new building under the license of a local electrician. I also have a basic knowledge of schematic reading and soldering.
    Originally I went to place all of the studio circuits on one leg and the fence on another but then I woke up and realized all the 240v 2 pole breakers made this idea a waste of time.
    Any ideas?
    Thank you!
     
  2. Adjuster

    Well-Known Member

    Dec 26, 2010
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    It is possible that you have less than ideal grounding of your mains power installation, either due to the way the original installation was made or due to subsequent alterations or damage. Perhaps it would be worthwhile getting it checked over again by a qualified electrician.

    That said, I think that operating a dog fence close to a recording facility is distinctly risky, as the principle of the system is to emit magnetic fields. Possibly re-routing the cable so that it is further from the studio might help.

    Something you might also want to check for would be whether there is any failure of insulation in the buried cable, which could be leaking current into the ground, so disturbing the local ground potential.

    Another thing to look for would be ground loop or screening issues in your sound equipment. Changing from single-ended to to balanced interconnects between equipment may help, if this is not how things are done already. This could be especially important with low-level devices like microphones (professional mics very often are balanced, so very likely you will have this covered already).
     
  3. colinb

    Active Member

    Jun 15, 2011
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    First take a close look at all the things Adjuster mentioned.

    Have you confirmed that the noise is present on the electrical supply lines? You said the pulse was pronounced, so perhaps you're already used an oscilloscope to detect the noise signal there. What is the nature of the noise? Is it a single, periodic pulse, or some continuous wave of some sort? Depending on the frequency, it might be possible to filter out the noise.

    Is the fence transmitter system causing the interference through its own electrical power connection to mains, or is it the buried fence antenna wire that is generating the interference? Maybe disconnect the buried wire and connect a length of wire as a dummy load at the transmitter -- if the problem goes away or is reduced significantly then it's the antenna sending interference; if it doesn't get much better, it might instead be that the interference is unintentional radiation out through the transmitter's power supply connection into your mains circuits. You could then do some power conditioning/noise filtering on the fence transmitter's own power supply to mitigate the problem at the source.

    Assuming power connections are transferring the noise signal into your studio and into the audio equipment, it should help to run all your studio equipment off a true uninterruptible power supply (UPS). Most low-cost backup power supplies for home use are not true “uninteruptible” supplies even if marked as “UPS” systems -- they are actually standby power supplies, and pass line power through to target devices directly until a power failure occurs and then rapidly switch to battery and inverter output. A true UPS should provide excellent power conditioning, but I can't guarantee it will not pass through some of the noise signal as well.

    Either way, you probably want all your expensive audio equipment protected by some kind of surge protection, voltage monitoring, and power conditioning system.
     
  4. Gavindale

    Thread Starter New Member

    Jan 2, 2012
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    Thank you both for your replies! I will try my best to provide the best information I can.
    The unit has LED lights on the front that pulse in time to the disturbance. I know that this system does not supply a straight current but a pulsing one instead. I followed and replaced 1/2 of the line recently and feel the inground wire is not the issue. So the unit itself is causing the problem due to its design. Like a intercom that uses your electric lines for transmission the same principle applies here.
    A new 200 amp box was just installed along with a new ground rod. This entire system from the transformer to this unit has 6 different grounding spots within a 150' radius. So poor or unmatched grounding I feel I can rule out due to the fact that this also was a issue before the changes.
    I don't own or know how to even use an oscilloscope!
    I already have plans for the studio equipment for surge and noise filtering but this is a issue that needs nipped in the bud where the wall wart unit power supply enters.
    I hope that helps. What next?
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
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    What is your evidence for "feeling" that the buried wire is OK - what about the half that wasn't replaced? have you tested it recently?
    It's not that I think that a cable leak is particularly likely to be the cause, but in my experience relying on assumptions of this kind without checking them often gets in the way of effective fault finding.

    Your assertion that the fault lies entirely in the design of the dog fence is also not proven until you have checked out whether there is some fault in the fence equipment, or in your mains wiring or the recording equipment. Would you really expect a dog fence to be energised with steady DC?

    Perhaps your next step would be to try to get some evidence on how the interference is reaching your equipment, for instance by the field from the fence interacting directly with your equipment, or if interference is really getting in from the mains. Is it possible to power the fence from a battery, at least for long enough to make a test?

    In the end, particularly if you are unfamiliar with test equipment, it may pay you to obtain the services of a local engineer to check over your recording set-up. Apart from the lack of surge protection, there may be some problem with shielding, or ground loops (the latter are not necessarily prevented by having satisfactory safety earthing).
     
    Last edited: Jan 4, 2012
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Line interference is really hard to determine and filter out. We cannot assume anything by talking. You have to do some practical work to find out whether the interference in being injected through the mains of ur units or through the grounding.

    You have to carry out one by one.

    For this we I need to know the type of ur equipment and how they are wired.

    What king of surge arrestors you are using and what are the line noise suppressors that you use.

    What kind of termination is being used in the Audio interconnects.

    You need to show us these things.
     
  7. Gavindale

    Thread Starter New Member

    Jan 2, 2012
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    I am now beginning to understand the border wire questions. You think that the DC current is building up and then discharging into the ground thus causing the pulse. I can assure you this is not the case. I knew this but checked with the manufacturer also. The unit is well grounded, the border wire is fine. The design is to send DC pulses and not a steady signal. This issue has been present since installation.
    The recording studio is still being constructed. Therefore no recording equipment is even in the picture at this time.
    This is a blowout remodel with the dog fence the only constant. I have always had the problem as it shows up when any guitar amp is plugged into the same circuit.
    It seems that my problem is not a diagnostic one but a straight question as to how to isolate this one "wall wart" transformer backfeeding signal to my breaker box. I have tried a "Monster" 2000 surge protector/signal filter but after calling I was told that their unit was not designed to correct a problem like this.
    I hope that clarifies my problem. A known cause looking for a straightforward solution. Thank you everybody!
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Then for this U need a scope to measure the noise
     
  9. Gavindale

    Thread Starter New Member

    Jan 2, 2012
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    OK. A scope to measure the noise. I am not familiar with scopes. Without taking me to another level far beyond my head.....what would I be looking for? My guess is, and I will go out and check with my multimeter, I would see a pulsing current draw. My guess is that the voltage will remain consistent even at the next receiptical. Again I will check.
    The problem is always very easy to experience whenever a tube amplifier is on. I don't know but suspect that a tube audio circuit is much more sensitive, especially with a single coil guitar that already is susceptible to 60 cycle hum.
    I apologize for my ignorance and inability to provide the correct data you fine folks need for this problem. I thought isolating a unit that causes this type of interference would be a common issue. I can now see it is not. I now understand that radio waves may be being induced and picked up by my tube circuit.
    Well if it's not too much trouble any additional help would be greatly appreciated!
     
  10. colinb

    Active Member

    Jun 15, 2011
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    Or, instead of trying to mitigate the interference from your dog fence system, perhaps you can buy a different system that will have lower interference. There is probably a variety of types of these systems, and hopefully some that have lower electromagnetic interference emissions.

    It would be interesting try running the electronic fence controller from a power source other than your line power -- something like a generator or a 12 Vdc -> 120 Vac inverter. If your interference goes away, then the EMI is radiated on the power line. If the interference remains, then it's the EMI transmitted via the buried loop or other means.

    So, the manufacturer says the loop can't conduct electricity through the ground to cause interference, but don't take their word for it. Anyway, it doesn't have to be a DC path. The ac current flowing in the buried antenna loop induces voltage in other conductors. The whole purpose of the buried wire is to transmit electromagnetic energy which is picked up by the collar unit, so it is little surprise that EMI can be a problem.

    Will the manufacturer give you any suggestions? Have other users reported EMI problems?
     
  11. Adjuster

    Well-Known Member

    Dec 26, 2010
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    You are making assumptions. I do not think anything about DC current building up and discharging: that is your thought process. If there is a leak at all (which I admit to be unlikely) it would be an AC current, not mains but more likely low radio-frequency, which would be going to ground.

    Fault-finding is not always a simple task requiring simple equipment. You are familiar with making checks with a multimeter, so that is what you would like to do, though other methods may be necessary. Well, you might get lucky, if for instance there is a leakage problem after all, but I would be surprised.

    More likely, there really is an EMC problem, getting to your amplifiers either through the mains, or otherwise. An ordinary multimeter may not be able to detect that, because the frequencies and levels involved may not be detectable by it. If you want to find the trouble either you may need to use other test equipment yourself, get someone else to do it for you, or make a set of systematic trials.

    Isolating the fence power supply might be a start. A battery would be ideal, as I suggested earlier, but of course may be impracticable, perhaps because the power required is too great. Somebody else has suggested a generator, which could provide much more power. Another thing that might help would be running the fence unit off a 1:1 isolating transformer. I'm not sure what your wiring codes would say about doing that in the long term, but surely you could do it for a brief test.

    If powering the fence other than by the mains kills the problem, a filter on the mains input to the fence would very likely help, as might filtering the DC feed from the power unit to the fence driver, if these are in separate units - did you say that the fence plugs in using a wall-wart?

    If isolating the mains is no help, running the fence driver into a temporary shorter loop kept well away from the amplifier might be another thing to try. Failing that, try locating the amplifiers in different places in the house.

    We await your comments.
     
  12. K7GUH

    Member

    Jan 28, 2011
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    I'm glad this isn't my problem. If it were, I would return the dog fence unit to the vendor immediately if not sooner. Assuming, of course, that the recording studio is more important than the dog fence. If not, I withdraw the suggestion. However, one might consider ordering a dog fence charger which the vendor guarantees will not cause electrical interference. You may still have to have a qualified electrician troubleshoot the entire wiring system.
     
    Adjuster likes this.
  13. Adjuster

    Well-Known Member

    Dec 26, 2010
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    +1 on that! I think that it is a mistake to assume that this is a simple problem. Interference issues may be complex - since we have an apparent source of interference, an unknown means of propagation (through the mains, or by magnetic coupling, or true radio transmission?), and finally the possibility of undue sensitivity in the amplifier.

    All of this will remain speculation unless some tests can be made. If this is impracticable, one alternative would be to try a different fence.

    This may not be the answer though, if the problem does lie in say a badly screened amplifier. Similar problems have been seen for instance where the neighbour of a radio amateur complains of TV interference. Sometimes this will be traced to a faulty transmitter, but in other cases a fault such as a corroded joint in the TV antenna may be causing a problem in response to a perfectly acceptable transmission.
     
  14. EB255GTX

    Active Member

    Apr 30, 2011
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    2
    Unplug the dog fence and tie the dog up or restrict it on another part of the property during recording sessions? Simple and cheap...
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Run the mains through metal conduit so it is shielded.

    Get a different fence.

    Get an electrician

    Those are my three ideas.
     
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