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Thread: Leviton GFCI nuisance tripping and circuit analysis

  1. #71
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    Probably doesn’t take make of any thing to help quench the peak of the kickback spike
    such as a capacitor, LC filter, etc

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    190111-2032 EST

    Larry Fine:

    In post #65 I was trying to point out what frequencies are typically called RF. Not whether those frequencies were radiated or conducted. I did say there were in use frequencies around 70 Hz that are probably used as radiated signals.

    Relative to sound and radio radiated waves. Both are radiated. Energy set in motion flows away from the source. In radio wave it is an electro-magnetic field. In an acoustic signal it is a pressure wave.


    tersh:

    If you have a pure LC low pass filter, and pulse it with a pulse much shorter in duration than the filter bandwidth, then the input energy is not lost going thru the filter, it is just modified. The output rate of rise is much slower than was the input. The peak output voltage is thus reduced, and the duration of the output pulse us greatly increased. The energy in the output pulse is the same as the input energy. I am describing total energy of the input pulse equals total energy of the output pulse.. That is the integral of instantaneous power input over the total time period of the input pulse is equal to the integral of the instantaneous power of the output pulse over the period of the output pulse. If the input pulse is rectangular, then the output pulse becomes rounded.

    This filtering is why your outlet strip labeled "Voltage Surge Protector" reduced the false trips of the GFCI. The fact that the false trips were reduced indicates that false triggering occurred from conducted noise energy, and not from radiated RF energy.

    .
    Last edited by gar; 01-11-19 at 09:10 PM.

  3. #73
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    Quote Originally Posted by mopowr steve View Post
    Probably doesn’t take make of any thing to help quench the peak of the kickback spike
    such as a capacitor, LC filter, etc
    Mine were inexpensive, considering I bought them from an AB wholesaler.
    Tom
    TBLO

  4. #74
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    Quote Originally Posted by gar View Post
    190111-2032 EST

    Larry Fine:

    In post #65 I was trying to point out what frequencies are typically called RF. Not whether those frequencies were radiated or conducted. I did say there were in use frequencies around 70 Hz that are probably used as radiated signals.

    Relative to sound and radio radiated waves. Both are radiated. Energy set in motion flows away from the source. In radio wave it is an electro-magnetic field. In an acoustic signal it is a pressure wave.


    tersh:

    If you have a pure LC low pass filter, and pulse it with a pulse much shorter in duration than the filter bandwidth, then the input energy is not lost going thru the filter, it is just modified. The output rate of rise is much slower than was the input. The peak output voltage is thus reduced, and the duration of the output pulse us greatly increased. The energy in the output pulse is the same as the input energy. I am describing total energy of the input pulse equals total energy of the output pulse.. That is the integral of instantaneous power input over the total time period of the input pulse is equal to the integral of the instantaneous power of the output pulse over the period of the output pulse. If the input pulse is rectangular, then the output pulse becomes rounded.

    This filtering is why your outlet strip labeled "Voltage Surge Protector" reduced the false trips of the GFCI. The fact that the false trips were reduced indicates that false triggering occurred from conducted noise energy, and not from radiated RF energy.

    .
    I put the LC filter strip between the Meiji GFCI and the Refrigerator to see if the ref would still trip and frequency. Before it tripped twice a day probably due to the shaded pole motor used in the fan in the ref. Do all ref use shaded pole motor based fan? (notice the refrigerator has no EGC and use 2 prong plug, it is brand new refrigerator).



    I can't find the spectrum of inductive kick. What are the frequencies involved? Is it also the source of all surges inside the building or house? The SPD people say surges come from outside and inside the building. What does it differ to RF noises and what creates RF noises?

    Do you know a reference that explains all of them at once? I only see unrelated reference and couldn't seem to combine all the concepts together. Thanks.

  5. #75
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    Quote Originally Posted by tersh View Post
    I was thinking if using isolation transformer for fridge for 240v users is safer than a 240v GFCI from an unknown manufacturer and especially with the information above.

    Say. What would happen when you connect an GFCI to an isolation transformer. Would it trip if there is leak from one live wire to ground? Since the ground is isolation, it shouldn't trip, should it?

    But connecting the shaded pole motor to the Meiji GFCI outlet and to a medical isolation transformer.



    The shaded pole motor still trips 4 out of 5 switchings (sometimes 100% trip 5 out of 5). The isolation transformer totally isolate the ground from source. It is a high quality medical isolation transformer with datasheet at http://catalog.triadmagnetics.com/Asset/VPM240-2080.pdf I got precisely to make sure the isolation is top notch. It even has dieelectric shielding between primary and secondary of the toroid which is difficult to manufacturer that is why it costs a lot.

    If you connect GFCI to a true isolation transformer, what instance can the GFCI still trip when the ground is supposed to be separated already?

    The url below mentioned the resistance of the human body was about 1500 ohms arm to arm, but there is something I'd like to ask clarification about. First in one of gar's 2 urls is this paragraph.

    "At voltages greater than 150 V, the resistance of the human body decreases dramatically and the fault current flowing through the body increases to unsafe levels requiring impossibly fast trip time. The purpose of the grounding conductor is to prevent the case or cabinet of a piece of equipment from exceeding 150 V if an energized conductor faults to it. The resulting current through the grounding conductor will also trip the GFCI to eliminate the danger of fibrillation."

    Look at this url:

    http://electronicstechnician.tpub.co...istance-34.htm

    resistance of the body arm to arm is said to be 1500 ohms. So if voltage is 240v.

    I=V/R = 240/1500 = 0.16A or 160mA

    Is this the context that as voltage increase, the current increases? (here the resistance stays constant).

    Or can the 1500 ohms go even lower that can further as voltage is increased?

    But isn't it the formula I=V/R already take into account the increased voltage?

    Or does it mean if the resistance gets lowered to say 1000 ohm. Then current is I =V/R = 240/1000 = 0.24A or 240mA?

    Compare this to the US electricity of I=V/R = 120/1500 = 0.080 A or 80mA only.

    What do you think?

  6. #76
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    From a controlled experiment 15 years ago on myself at 60 YO:

    with both my feet in 14% NaCl solution to 3" above the ankle at 20 mA 60 Hz measured 420 ohms.
    btw, at the salt water level on one's legs at 20 mA there is an INTENSE burning sensation at the water line that goes away when current turned off

    CAUTION - DO NOT TRY To REPEAT THESE TYPE EXPERIMENTS AT HOME.

    If you can find a copy, a definitive treatise on impedance and shock and fibrillation is in Berglemiester's paper:
    Dr B literally electrocuted himself with defilb equipment and medical doctors standing by.

    Dr. G Biegelmeier, New knowledge on the impedance of the human body. (1985 PAPER)

    https://ethw.org/Oral-History:Gottfried_Biegelmeier
    https://www.sciencedirect.com/scienc...8025399250014X


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    Quote Originally Posted by junkhound View Post
    From a controlled experiment 15 years ago on myself at 60 YO:

    with both my feet in 14% NaCl solution to 3" above the ankle at 20 mA 60 Hz measured 420 ohms.
    btw, at the salt water level on one's legs at 20 mA there is an INTENSE burning sensation at the water line that goes away when current turned off

    CAUTION - DO NOT TRY To REPEAT THESE TYPE EXPERIMENTS AT HOME.

    If you can find a copy, a definitive treatise on impedance and shock and fibrillation is in Berglemiester's paper:
    Dr B literally electrocuted himself with defilb equipment and medical doctors standing by.

    Dr. G Biegelmeier, New knowledge on the impedance of the human body. (1985 PAPER)

    https://ethw.org/Oral-History:Gottfried_Biegelmeier
    https://www.sciencedirect.com/scienc...8025399250014X
    When a person suffers fibrillation, why is death sudden? Does it immediately shut down the brain? In gunshot victims to critical body parts. they don't die suddenly, but those who were electrocuted died suddenly. If the heart stopped beating, does brain shut down immediately and death follows 2 seconds later??

    for professional engineer eyes only




    This is to remind even professionals that electrocution doesn't give you second chance.. so only let professional electrician connects anything electrical with fully body protection (like electrical gloves and googles).

    This is also why I won't buy any oscilloscope and try to see the inductive surge spectrum of the shaded pole motor and what part of the GFCI circuit trips when exposed to these inductive kicks. Let professionals with full laboratory equipment trained handling it figure it out.

  8. #78
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    Quote Originally Posted by tersh View Post
    When a person suffers fibrillation, why is death sudden? Does it immediately shut down the brain? In gunshot victims to critical body parts. they don't die suddenly, but those who were electrocuted died suddenly. If the heart stopped beating, does brain shut down immediately and death follows 2 seconds later??

    for professional engineer eyes only
    Maybe it was actually the energized water around the pole.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #79
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    Quote Originally Posted by tersh View Post
    When a person suffers fibrillation, why is death sudden? Does it immediately shut down the brain? In gunshot victims to critical body parts. they don't die suddenly, but those who were electrocuted died suddenly. If the heart stopped beating, does brain shut down immediately and death follows 2 seconds later??

    for professional engineer eyes only




    This is to remind even professionals that electrocution doesn't give you second chance.. so only let professional electrician connects anything electrical with fully body protection (like electrical gloves and googles).

    This is also why I won't buy any oscilloscope and try to see the inductive surge spectrum of the shaded pole motor and what part of the GFCI circuit trips when exposed to these inductive kicks. Let professionals with full laboratory equipment trained handling it figure it out.

    I googled a lot about electrocution or fibrillation and loss of consciousness but not much direct hits. However. When I entered "cardiac arrest and loss of consciousness". There are many hits. So what happens in cardiac arrest is really lost of consciousness. In electrocution, one is inducing cardiac arrest.

    https://www.everydayhealth.com/heart...rt-attack.aspx

    "
    A heart attack and cardiac arrest, though both significant and dangerous, are two different cardiac events. Heart attacks happen when too little blood flow gets to the heart, but in cardiac arrest, the heart malfunctions and stops beating, at which point a person may suddenly lose consciousness."

    If only consciousness wouldn't occur suddenly after one got fibrillation from electrocution, one could use defibrillator on oneself (by maybe bringing one in knapsack, no such emergency kit an electrician can bring, isn't it?).

  10. #80
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    Quote Originally Posted by tersh View Post
    ....... won't buy any oscilloscope and try to see the inductive surge spectrum of the shaded pole motor and what part of the GFCI circuit trips when exposed to these inductive kicks. Let professionals with full laboratory equipment trained handling it figure it out.
    hmmm, profile lists 'engineer'? An engineer afraid to hook up a scope to simple 240 V 60 Hz? Untrained and an engineer? a locomotive or 'sanitary' engineer?

    All you need to do to get your full data is to hook up a scope with a current probe (you don't even have to touch any 240 V wire with a clamp on probe) and look at the waveform. You will undoubtedly SEE a differential current at transitions.
    Gar probably has already taken some waveforms and waiting to see if any others have

    Using a small SP motor I see differential currents in the 10o's of mA at switch operations.
    Another hint: the inductance of small sp motor is 500 mH, a 1/2 HP motor is only 2.6 mH - what does that tell you?

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