Re: electric strength for "x" cm of "y" material

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Finn Hammer <f-h@xxxx>

All,

Well that post sure got garbeled into non-recognitionability. I tried 
sending the table to myself a couple of times to see if it worked, 
and it did. But it did not make it across the pond, I`m afraid..

If I try to fill the whole space with dialectric, so that there is 
only a small distance of air, which field strength will be present in 
this small gap. Before putting this into the spreadsheet I thought it 
might increase towards infinity. It does not. It increases towards 
the field strength of the total gap, multiplied by the dielectric 
constant of the poly. The field strength inside the poly in turn 
varies from (for thin sheets) the field strength divided by the 
dielectric constant to the field strength in the case of a thick slab.


Cheers, Finn Hammer

Tesla list wrote:

> Original poster: Finn Hammer <f-h@xxxx>
>
> Antonio, Stephen,All,
>
> This opened my eyes to the source of some problems i have been facing lately.
> I put the concept into a spreadsheet and found out that with an 
> air/poly sandwich in an electric field, the field strength in the 
> remaining slot of air increases toward a maximum, which is the total 
> field multiplied by the poly`s dielectric constant.
>
> Electric field in air - polymer sandwich
>
> Poly dielect. constant=     4
> Total field kV =    100    Distance mm=    100
> Field MV/m           1 airthick     polythick     airdrop kV
> polydrop kV     airfield
> polyfield
> 1                   99               3,88
> 96,12             3,88         0,97
> 10                 90             30,77               69,23
> 3,08         0,77
> 20                 80             50,00               50,00
> 2,50         0,63
> 30                 70             63,16               36,84
> 2,11         0,53
> 40                 60             72,73               27,27
> 1,82         0,45
> 50                 50             80,00               20,00
> 1,60         0,40
> 60                 40             85,71               14,29
> 1,43         0,36
> 70                 30             90,32                 9,68
> 1,29         0,32
> 80                 20             94,12                 5,88
> 1,18         0,29
> 90                 10             97,30                 2,70
> 1,08         0,27
> 99                   1             99,75
> 0,25             1,01         0,25
>
>
> I don`t understand how to add the information in Antonio`s  post into this.
>
> Cheers, Finn Hammer
>
>
> > Original poster: Steve Ward <steve.ward@xxxxxxxxx>
> >
> > Well, say there is (just throwing out random numbers) 50kV between 
> > 2 conductors and they are seperated by 10cm.  The electric field 
> > (with just air) would then be 500kV/m.  But say we introduce a 5cm 
> > thick sheet of some poly material where its dielectric constant = 
> > 2.  That would make the electric field in the air become twice that 
> > of inside the plastic, right? But we must still arrive at our 500kv/m figure.
> > So there should be 16.6kV "dropped" across the plastic, and 33kV 
> > "dropped" across the air... except now we only have 5cm of air, so 
> > now the E-field in the surrounding air would be 666kV/m.  I believe 
> > this can cause problems in some cases with corona forming.  Please 
> > correct me if my theory/understanding is incorrect here.