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Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
does anyone know the dielectric constant for NaCl (uniform solid crystal)... assuming no moisture? I may not use it, but I have been thinking of doing some experimentation with electricity induced fractures in crystals...
and oil is always a good idea, anything that I want to last long that I do not plan to adjust (above 5kV) I put in oil... same for long runs of wire that are too long for HV wire, the wire goes in a tube filled with oil with something to hold it in place...
also, this might be a good idea for the wiki: real world uses and ratings for dielectrics
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
DaJJHman wrote ...
and oil is always a good idea, anything that I want to last long that I do not plan to adjust (above 5kV) I put in oil... same for long runs of wire that are too long for HV wire, the wire goes in a tube filled with oil with something to hold it in place...
Registered Member #4022
Joined: Fri Jul 22 2011, 04:36AM
Location: Indonesia
Posts: 9
Hi mates .... Whether in making the capacitor does not require a mandrel in the middle so that there is no possibility of air entering into the capacitor ....?
Registered Member #3700
Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107
Hi !
I have been involved in this matter for years...
a- it is really hard to eliminate any air portion in the cap assembly. Even with vacuun and oil impregnation the hv cap may have some air portion that will glow and produce ozone... damaging the solid dielectric...
The solution for that appears not be new. What about:
1- Design a capacitor that have a dielectric media compound of air dielectric and solid dielectrc. ?
2- The relation between the air dielectric thickness to the solid dielectric thickness is such that the voltage gradient is lower than the corona voltage level.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Does the field intensity play a role in oil break down? i have field sims showing 12MegaVolts/m on 0.5mm distances with 14kV applied, to plates 0.004 radius thick, 1.4mm apart in oil, but an average of 310V per mil?(or 12KV per mm) Any advice?
Density plot, Rounded edges, without equipotential lines. Im getting a calulated intensity of 14kV/0.055" = 254V/mil But the program shows 45,000V/mil !? how is this possible? (The orange in the middle gap is 1.711e9 V per m.)
UPDATE: my thread here explains what ive found->
Patrick wrote ...
UPDATE:[/size]
pics Voltage plot. (right side has rounded edges) Upper magenta is 14kV, lower cyan is 0 volts, midpoint of gap is yellow 7 kV as would be expected.
Field density plot, V/m. Left side, right angled edges W/ equipotential lines.
Density plot, Rounded edges, without equipotential lines.
Density plot, Rounded edges, with equipotential lines.
Round edges, Density plot, zoomed in.
Square left end, voltage plot.
Horizontal top plate should be 14kV, lower plate 0V, two circles at right and left should be 7kV, DXF is in inches. I cant figure out how to work this dam software! ( DXF file for FEMM4.2)(newest)
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60KV 3.5 nF home made caps - complete protocol
