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Re: dielectric constants
From: teslaman-at-juno-dot-com[SMTP:teslaman-at-juno-dot-com]
Sent: Thursday, November 06, 1997 8:45 PM
To: tesla-at-pupman-dot-com
Subject: Re: dielectric constants
On Wed, 5 Nov 1997 16:39:35 -0600 Tesla List <tesla-at-pupman-dot-com> writes:
>
>From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
>Sent: Tuesday, November 04, 1997 7:07 AM
>To: Tesla List
>Subject: 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
>>
>>
>>
>>
>
>Kevin,
>If there are additives in the oil, then the high readings may in fact
>be due to
>conductance rather than capacitance. Some capacitance meters measure
>the ac
>current flow, and any conductance is displayed as if it were
>capacitance. You
>can check this out by paralleling the capacitor with a high value
>resistor
>(100s of K to Megohms). If the capacitance read goes UP appreciably,
>then it is
>affected by conductance. Use a digital OHM meter on its highest range
>and see
>if the oil has any measureable conductance. If so, you have identified
>the
>source of error.
>
>Fr. Tom McGahee
>
>
>Fr. Tom, Jim..
You were right, the problem was the digital meter and the way it
measures capacitance. Adding parallel resistance to the test capacitor
caused the reading to increase. Another test was made with the variable
capacitor in motor oil using the LCR bridge 10 whole feet away and
capacitance only went to 2.18 nF. I had used the fluke 83 because of
convenience, I'll use the bridge from now on though :)/-< Live and
learn.
Kevin E.
>