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Re: dielectric constants
From: Teslaman-at-aol-dot-com[SMTP:Teslaman-at-aol-dot-com]
Sent: Monday, November 03, 1997 4:30 PM
To: tesla-at-pupman-dot-com
Subject: dielectric constants
All..
After hearing of different oils and dielectric constants for capacitor
building, I ran a simple experiment. Using a variable capacitor from an old
tube type radio and measuring its capacitance with air as the dilectric, and
then immersing in different oils I have come up with a list of dielectric
constants.
The capacitor had a full mesh reading of .96 nF. The capacitor was cleaned
in solvent & air blowed dry between each oil immersion. For the 90w oil
test, the oil was heated to 100 deg.F. to saturate the capacitor plates
better.
capacitance
diel. constant
begining capacitance in air. .96 nF
1
In pharmaceutical mineral
oil (or baby oil) 2.08 nF
2.17
In canlola cooking oil 3.28 nF
3.42
in 90w mineral gear oil
at 100 deg F 18 nF
18.75
in 30w motor oil 55 nF
57.3
As can be seen there is a wide range, can't figure the high motor oil
reading though, possible additives causing high readings? Any comments or
suggestions?
I'll perform break down voltages for each oil on another day. Of coarse a
high dielectric constant does not necessarily make it a good choice for
capacitor construction. The flash points may make some dangerous to use if a
spark occured in a sealed capacitor with any air in the enclosure. Also the
thicker the oil the more easily the high voltage electric field will force it
away from the foil edges of a capacitor as noted in other experiments of
past.
Kevin E.