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THD Measurements From Electric Company!

Discussion in 'Audio Hardware' started by Soundgarden, Jan 13, 2021.

  1. Ingenieur

    Ingenieur Forum Resident

    No, only the channel that the current flows on.

    The overnight stuff:
    My guess is the fan is on one ch and the frig on the other.
     
  2. Ingenieur

    Ingenieur Forum Resident

    The furnace fan is on one ch, the fridge on the other.
     
  3. Ingenieur

    Ingenieur Forum Resident

    That is correct but they are out of time synch.
    They are 2 different devices, likely fridge and furnace.
    Since he has gas the only 240 loads may be a clothes dryer and AC unit.
     
    Oelewapper likes this.
  4. Ingenieur

    Ingenieur Forum Resident

    The THD for 240 can be mathematically derived, and usually moot that is why they don't measure it.
    For V the difference
    For I the sum
     
  5. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    For the sake of argument, let's say that the alternating cyclings between Ch1 and Ch2 are from the furnace fan and the fridge. Strikes me as pretty odd that they'd have the same pattern. Right? Each is on for 10-15 min then off for 30-40.
     
  6. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    I actually don't know myself. I haven't experienced this yet. But amongst all the things that people do, there's a wealth of input from others who have done this and experimented with other changes to their AC, like better outlets, power cords, etc. and say this can be really helpful.

    I'm not interesting in spending a bunch on AC power quality. Snake oil? Certainly some of it. But at the very least I'd say it's more appropriate for folks with big bank accounts, super hi-end systems, and well-trained ears.

    But. I have an electrician coming out to do a bunch of other work already. The cost of throwing this is when everything's opened and he'll already be down in the crawlspace isn't much more. I'm going to have him just do a simple line, using standard 12-2 and Hubbell HBL5362 outlets, which are $20 a pop. Will I hear a difference? I don't know. I'll still have the 15A outlet to draw from, so I can test. Maybe I won't hear anything... but I'll be evaluating for noise floor and SQ. And certainly will write back afterwards with my impressions.

    Would I be doing this if the electrician weren't already coming out? I don't know. Maybe. I'd definitely be on the fence. But curiosity may still push me to do it.
     
  7. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    So my general understanding is if you're hearing a lot of buzz, the audio signal itself is going to be degraded as well. Correct?

    The buzz is of course an issue on its own. No question there. Changes to the audio signal may be less noticeable. But at a certain point, for those of us with resolving systems and an ear for detail, it can be an issue too.
     
  8. TarnishedEars

    TarnishedEars Forum Resident

    Location:
    Seattle, WA
    It keeps lots other devices which share the same circuit from pouting your power as much. This is not just an opinion, this is a measurable phenomenon. Although obviously the fewer rooms and/or devices which share a circuit, the less difference a dedicated circuit makes.
     
  9. Oelewapper

    Oelewapper Plays vinyl instead of installing it on the floor.

    With decent power supplies and no exceptional circumstances (ie. very noisy devices on the same group), I don’t think it’ll make a difference.
     
    Soundgarden likes this.
  10. Ingenieur

    Ingenieur Forum Resident

    my WAG
    ch 1 is the furnace fan on a switching speed controller since THD is max while running.
    It's duration varies imo based on outside air temp.

    The lower ch2 is the refrig with a big starting spike and settles down after running. An across the line motor makes less THD than a SS speed controlled one. It's duration is more consistent since room temp varies little and the fridg takes the same time to warm up and cool down when running.

    Do you have a programmable t-stat that resets up at 8 AM? And kicks down at 11 pm?
     
  11. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Nope. But I often have the gas fireplace on during the day and get a bunch of sun from south facing windows. Also warm winter up here this year. So The heat doesn't go on much during day time hours.
     
  12. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Here are four days worth of data, Wed Jan 6, Sat Jan 9, Sun Jan 10, and Tue Jan 12. More or less makes my head spin. At least after seven hours of zoom calls.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  13. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    Again, you're fretting over nothing, at least nothing within your control. They would have recognized faults (like a voltage drop from failing ground conductor to pole) by now.

    The harmonic distortion percentage is what's coming into your house, not so much that which is caused by you.

    Where the THD drops to zero regularly in these current measurements is simply that the meter can't measure when there isn't enough current flowing in wires. The distortion is still there. Accuracy is likely also impacted with lower and changing currents. Voltage graphs are what you should be looking at, where you'll more easily see changes due to daily grid utility use.
     
    Shawn and Glmoneydawg like this.
  14. CoolJazz

    CoolJazz Forum Resident

    Location:
    Eastern Tennessee
    The thing to try to do with the residential electric panel is this...balance the panel with the goal of having the two legs fairly equal for while you're likely to do a listening session. The better balance, the lower the distortion will be. Also, try to have it arranged so that the audio system leg is feeding the cleaner loads...like resistive loads, rather than electrically noisy.

    While the electrician is moving a few loads around to do the best balance that achievable, make sure all lugs get checked for tightness. The heavier the load, the more that lugs work slightly loose. Every bit of loosing raises impedance, heat at the lug connection and increases noise. In commercial work, it's a common practice to recheck lug tightness every two years. Residential due to the lighter load, I've never heard of a recommended check interval.

    Reaching the dedicated, hopefully heavier gauge feed, back to the panel for your system means you are pulling from a lower impedance point where less noise gets impressed from your loads. You see, most noise on electrical is from your own loads. Not external.

    If you could reach your feed point back to the transformer, you'd be incredibly clean! That's what the big step down transformer does. Creates a low impedance, low noise point.

    The bigger the gauge coming from the panel main out to the far end drop point, it's helping drag down impedance and noise to as low as possible. The further you get out away from the panel (especially with a drop that goes through several boxes) the higher the impedance and the easier it is for noise to get impressed onto the wiring. As you go back down the wire towards the box and the lower impedance, the noise gets less and less. But that amount of wiring is now able to radiate the HF noise.

    CJ
     
  15. Ingenieur

    Ingenieur Forum Resident

    You can see days you weren't home lol
    The first one, afternoon

    did you listen to music 6 to 9 on the second one ch 2?
     
  16. bdfin

    bdfin Forum Resident

    Location:
    Washington State
    It's more what you're not hearing. Darker quiet background, seems more focused, and most important no extra humming or buzzing plus I had grounding issues showing fault on power strip which was eliminated. I just bought new box, breakers,upgraded outlets but not super fancy. Plus this was in a shed basically that was expanded so I could run the line on the outside of the interior walls in plastic electrical conduit so I didn't have to pull any wires through long wall runs and I didn't need to hire anyone to do the work. Just needed to be very careful around electrical power.....not promoting do it yourself unless you know what you doing. It was worth the 200.00 bucks I spent on the parts and wire etc. and eliminated aged power box and gave me much cleaner power supply to A/V gear. YMMV if you are just adding line from already good main box etc. your improvement could be less dramatic or even minimal. It was a huge difference for my particular situation.
     
    motorstereo and Soundgarden like this.
  17. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    So what I've taken away from this is that a) my THD on voltage is good and b) my THD on current, although it may look super messy, doesn't show anything to worry about. If I had really wanted to understand it with greater detail, I would've needed to set some control variables during the time the tracer was on.

    So moving on... I'm wondering what's the easiest way to check for noise at the outlet for purpose of understanding how noisy my different circuits might be? There are some products with LEDs that light up as a means of capturing distorted energy from the circuit. Like the PS Audio Noise Harvester: Noise Harvester AC cleaner

    Seems pretty clear that if it blinks a lot less on my dedicated circuit than my standard house circuits that my dedicated circuit has cleaner power. This would indicate relative levels of cleanliness from circuit to circuit. Has anyone done this or used something similar?
     
    Last edited: Jan 17, 2021
    Ingenieur likes this.
  18. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    And I could also use the harvester to determine which household appliances have the most pronounced impacts on different circuits. Like the washer, dryer, fridge, furnace fan, etc. That might be interesting actually... I wonder if there's a cheaper tool for this though than $99 noise harvester.
     
  19. zonto

    zonto Forum Resident

    Location:
    Boston, MA
    Entech or a SureTest circuit analyzer?
     
    Soundgarden likes this.
  20. motorstereo

    motorstereo Forum Resident

    Location:
    Ct.
    Soundgarden likes this.
  21. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    So then this device reads out voltage and noise separately on the digital display and also has the speaker. Does the level adjustment just affect the speaker volume? This seems like what I'm looking for. Better for this purpose than the harvester. Thanks!
     
  22. VinylSoul

    VinylSoul Forum Resident

    Location:
    Lake Erie
    Have you notified the utility that they had best clean up their act and that your tired of dirty distorted AC?
     
  23. Soundgarden

    Soundgarden Forum Resident Thread Starter

    Location:
    Bend, Oregon
    Assuming that's a joke...
     
  24. motorstereo

    motorstereo Forum Resident

    Location:
    Ct.
    Yes the volume gets louder as the numbers go up. This really is a useful device for tracking down noise. My noisiest component so far has been led dimmer switches. I also switched over my 120 legs for my system as one leg is noisier than the other one. It's also useful for testing "power conditioners". Some of them really do their job well, some reasonably well and some actually add noise to the line. This unit is also the reason I say those PS audio harvesters don't do a damn thing. Have fun
     
    Soundgarden likes this.

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