AC Current Flow Question

[crossman]

Ray and Zog:

In your understanding of the phenomenon at hand (single phase xfmr secondary with one terminal connected to earth and the other terminal connected to an isolated conductive body), is there any mechanism other than the standard mechanisms of resistance, capacitance, and inductance, that can serve to allow current to flow into or out of the xfmr secondary?

If the answer is "no" then we have been on the same page since day 1.

If the answer is "yes", then my knowledge is lacking and I would like to know more about this. Can you give any references or links where I could do more research? Are there any equations or formulas which could be used to compute this current flow which does not rely on capacitance, resistance, or inductance?

 

[RayS]

yea, we have a 3rd voter for the 80mA option in the poll!

crossman-
yes. I say simple charge flow should be on the list. I know, some say it's really just capacitance, others say electrostatics can't flow current, but I disagree.
Although usually of trivial importance, in your examples with no hardwired connections it could be significant.

this site
http://www.glenbrook.k12.il.us/gbssci/phys/Class/estatics/u8l1c.html
was a big help to me in breaking it down. It was referenced in the other thread.
I gotta admit it's been a long time (20+ years) since electronics class. For what it's worth, I'm giving some serious thought to going back to school once I ship my kids off to college in a few years.

 

[crossman]

yes. I say simple charge flow should be on the list. I know, some say it's really just capacitance, others say electrostatics can't flow current, but I disagree.

Ray, I am very very much in appreciation of your simple and direct answer. At least we have some common ground to what we are talking about. Honestly, I do appreciate it!:smile:

Obviously I am on the side of "capacitance" rather than "simple flow of charge".

I have already given my thoughts on the subject, so not much left to say at this point. I would put forth the following question though:

If this is a fourth method of causing electrons to flow from the xfmr secondary to the conductive body, surely the physicists know about it and understand it. And surely they would have created formulas and math based on the physical characteristics and voltage of the secondary and the physical characteristics of the body which can determine the amount of current that would flow to and from the body using this mechanism?

I would like to see those formulas if anyone has them somewhere.

Edit: add: Ray, I am going to say the link you gave is for electrostatics and attraction of charged masses to one another, not so much to voltages and current flows in xfmr secondaries. Still, in the xfmr, the like repels like and opposites attract still hold. And I see capacitance. I have been wrong before, perhaps I am wrong here.

 

[weressl]

Electrons dont jump through air huh? What is an arc? How do you know what the voltage is in Crossmans drawing? Ib elieve it is around 500,000V because this whole discussion started from a 500kV transmission line. Also the transformer secondary is not insulated, I know this because he is reproducing a experiment I did with a 100kV hipot.

You sure do make alot of assumptions and turn them into facts. I am not saying your theory is wrong at all, just your assumptions.

Electrons continually migrate through ANY material, sometimes quickly sometimes slowly.

 

[RayS]

crossman, here's a formula, edited to the conclusion, and part of an example, also edited for brevity. Much interesting stuff that relates to this discussion can be found on the page I got this from- "energy of electric charge" is just past the Kirchoff part. Interestingly enough, part of the equation is the capacity- this is what I see as the precursor to capacitance. Enjoy!
http://kr.cs.ait.ac.th/~radok/physics/k5.htm

...consider eV/2 to be the exact value of the work, which must be performed to load the body with the quantity of electricity e.

An example: An unelectric body - its charge is e = 0, and therefore its potential V = 0 - is loaded by an electric machine to the potential V = 5000 Volt (5000/300 units of the electric potential) and its capacity demands for this e = 6�106 units of electricity. (These numbers can be achieved with good electric machines. 6�106 units conducts a current of 0.002 Ampere per second through the cross-section of the cable.) How large is the energy store of the body in this state of charge or how much work performs this charge, if you discharge the body completely through a cable to Earth?...
... In other words, the body, as it discharges its electricity, can perform 0.51 mkg* (that is, as much work as 1 kg* can perform as it sinks by 0.51 m), provided that all of the energy, stored in it, becomes mechanical work.