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webby1

• Hero Member
• Posts: 3117
Question about a multi plate cap
« on: September 24, 2016, 03:45:15 PM »
If I have a 4 plate capacitor such that the plates are all the same size and the distance of separation between plate 1 and 2 is the same as 2 and 3, which is the same for 3 and 4, and the distance between 4 and 1 is the same as 1 and 4.

Plate 1 being charged positive, 2 negative, 3 positive, 4 negative, and the capacitance between 1 and 2 being 1F, and between 2 and 3 1F, and between 3 and 4 being 1F.

If I charge plates 1 and 2 to 10V and then I charge plates 3 and 4 to 10V.

Will there be a voltage between plates 2 and 3?
Will there be a voltage between plates 1 and 4?

If I discharge plate 2 to 3 what will happen to 1 and 4?
If I discharge plate 1 to 4 what will happen to 2 and 3?

I only have a 3 plate case common cap to play with,, so I do not know the actual answers here and Google was of little to no help.

I was thinking that the capacitance between plates 1 and 4 was 0.5F,, not sure but that makes it easier for me to think about but still not sure.

I was also thinking that the capacitance between plates 2 and 3 would also be 1F.

The plates are of course separate plates.

Question about a multi plate cap
« on: September 24, 2016, 03:45:15 PM »

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #1 on: September 26, 2016, 11:49:42 PM »
Well,, with no input I went ahead and played with what I have.

the 3 plates using the case as common are rated at

Plate 1 20Uf  +
Plate 2 40Uf  -
Plate 3 80Uf  +
Plate 4 case  -

10 Volts set on PS

Charge P1 to P4  10V
Charge P1 to P2  10V
Charge P3 to P4  10V

Short P2 to P3 6V showing

Charge P1 to P2  10V  it was 8V showing

P1 and P4 show 15V

Trying various such connections but without the shorting I was getting many values from my 4 meters going sometimes negative,, I think I shorted by reverse polarity of the charge on that one,, but I was getting ranges on P1 to P4 up to 18V,, and the others were bouncing up and down from about 6V up to about 12V.

So one question is answered in that the plates even when charged separately still have a stored potential between the two plates,, so I charge P1 to P2 and P3 to P4 I get voltages on P1 to P4 and P2 to P3.

Using those potentials does change the others,, I was playing the shorting chase game for a while until I just shorted all of them at the same time.

shylo

• Sr. Member
• Posts: 475
Re: Question about a multi plate cap
« Reply #2 on: September 27, 2016, 11:44:03 AM »
Hi webby1, I'm seeing the same thing in my cap banks.
I'm just using regular caps , series/parallel configurations. (I keep trying different arrangements)
I use the banks for drive input to spin the rotor, which in turn charge the banks.
The trick I'm seeing is pull potential from the plates that aren't connected, leave the others alone.
Interesting.
Thanks artv

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #3 on: September 27, 2016, 02:54:24 PM »
Hi artv,

I have noticed that reaction from cap banks myself,, I kind of got irritated with it at times when you are trying to zero all the caps out and some just don't want to give it up.

I am curious about what happens with the plates when they all share the same volume in space.

That is that when I charge one plate to another that very same charge and input interacts with the other plates.

I also took this further in thought,, what if I have 4 wires wrapped in a coil on a non permeable core,, would each of those wires then also act as a capacitive plate,, they do meet the needs for a capacitor.

If I stuff charge carriers into one wire and suck them out of another wire then the "coil" would be charged like a capacitor,, and I would then think that I could change this capacitance by how many charge carriers are allowed to be added and removed by allowing some of the added and removed charge carriers to move elsewhere,,

shift 10 coulombs of charge carriers,, use 2 of them to do something else leaving 8 "stored" within the wire plates themselves.  Use none and they are all stored,, use 9 and you only have 1 stored,, use all of them and you have none stored.

One difference I see with this train of thought would be that the stored and used relationship might be related to the flux produced.

Not sure where this is leading,, but it is interesting how there is so much interaction when the plates occupy the same volume as each other.

shylo

• Sr. Member
• Posts: 475
Re: Question about a multi plate cap
« Reply #4 on: September 27, 2016, 10:06:52 PM »
"One difference I see with this train of thought would be that the stored and used relationship might be related to the flux produced"

I agree, the inducing flux of the rotor alters the way it  behaves of the charge carriers..
All the charge carriers have that opposite field associated with them, I'm trying to utilize and understand
Very interesting indeed.
artv

Re: Question about a multi plate cap
« Reply #4 on: September 27, 2016, 10:06:52 PM »

thx1138

• Jr. Member
• Posts: 92
Re: Question about a multi plate cap
« Reply #5 on: October 05, 2016, 12:29:44 PM »
The dielectric in the capacitor, not the plates, stores the charge. The plates are there to facilitate the movement of charge into and out of the dielectric .

Since the plates have two sides, the charge going into plate 2 also affects the dielectric between between plates 2 and 3 so aligns the charges in that dielectric also. And since plate 3 is in contact with the dielectric between plates 3 and 4, the dielectric between plates 3 and 4 also gets charged but to a lesser degree because it is further from the source.

See the portion of this video beginning at 1:00.

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #6 on: October 05, 2016, 01:42:15 PM »
It is interesting that charge carriers are moved into and out of the plates to cause a shift in the charge balance of the dielectric which itself looses no charge carriers,, but rather they are shifted like a spring.

It takes work to remove the dielectric from between the plates and in doing so increases the voltage on the plates with the same number of Coulombs stored.

Does all this stuff not infer then that there would be sequence for charging a multi-plate capacitor that could yield a difference?

Re: Question about a multi plate cap
« Reply #6 on: October 05, 2016, 01:42:15 PM »

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #7 on: October 08, 2016, 01:19:05 PM »
Another interesting thing to ponder is how does the dielectric reduce the electric force of attraction and repulsion on the plates?

If I have a dielectric between the plates I can move electrons into one plate and out of another plate easier,, try doing that without the dielectric, the same amount of charge carriers will take much more effort.

In this context the dielectric does not store the energy,, it stores some energy from some interaction,, but not what is between the electrons and protons on the plates.  Those very electrons and protons are squished together with the addition of more or stretched apart with the removal of some,, and somehow the dielectric is able to change the level of effort to make that happen.

Also,, if I remove the dielectric there is no loss in stored energy for the plates,, because it takes effort to remove the dielectric means you are adding that energy into the dielectric and not the plates,, or does it mean that it takes effort to reduce the stored amount in the dielectric.

It seems there might be some unanswered questions, or am I the only one that sees this condition as I have described?

shylo

• Sr. Member
• Posts: 475
Re: Question about a multi plate cap
« Reply #8 on: October 09, 2016, 06:00:49 AM »
What I find interesting is with some connections the caps hold their charge alot longer than with others.
It's like they are feeding back through themselves.And if you spike it at the right time, it reinforces the initial charge.
artv

Zephir

• Sr. Member
• Posts: 382
Re: Question about a multi plate cap
« Reply #9 on: October 09, 2016, 10:25:50 AM »
Captret effect maybe ? https://www.overunity.com/9878/captret-capacitor-and-electret
But it's difficult to judge without exact schematic or photo..

Re: Question about a multi plate cap
« Reply #9 on: October 09, 2016, 10:25:50 AM »

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #10 on: October 09, 2016, 03:55:51 PM »
Also look out for an AC voltage sitting on the caps,, I would get that from time to time lasting for for several minutes.

webby1

• Hero Member
• Posts: 3117
Re: Question about a multi plate cap
« Reply #11 on: October 10, 2016, 07:19:23 PM »
Ever removed a cap from its case and connected to the end of the plates?

Ever done that and then placed another coil around,,, at least the bottom of ,, the cap?

I think I messed up the cap since it does not want to hold a charge,, it leaks down within 30 seconds from 10V.

If I feed the cap AC via one of the "new" connections and the other plate by its old connection and then measure the coil,, interesting that there is an AC voltage measured,, not much mind you, like about .236V AC,, when I pump in via the coil I only get like about 0.004V AC on the cap.

Then when I charge the cap and use one side of my meter going to the coil and one side going to the cap there is a reading,, short the coil to cap it goes to zero, open it and it comes back,, but like I said I think I messed the cap up because it now leaks down quickly,, not sure if it did before however,, but measuring ohms shows no connections.

I still measure the same voltage whether using the "new" connections or the old ones,, but how much it takes to fill I have no idea about.

Don't let the cap unwind while you are accessing the ends,, I did and that is most likely when I messed it up,, or I think I saw a small flash on the first power up,, not sure if it was an arc or just light bouncing off of the shiny parts.