Re: [PSUBS-MAILIST] Pressure compensation

["D. Blake" <dblake@bright.net>]

No problem Ken.  I guess then a brushless DC motor sealed in oil would be
the ticket  along with a magnetic coupling for the prop.  Probably have to
take out a loan from the mutual funds account though :>)
Having Fun,
Big Dave

-----Original Message-----
From: Subscuba@aol.com <Subscuba@aol.com>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Sunday, August 13, 2000 6:44 PM
Subject: Re: [PSUBS-MAILIST] Pressure compensation


>In a message dated 8/12/00 2:00:37 PM Eastern Daylight Time,
>dblake@bright.net writes:
>>
>> Use of an oil that is typically used in refrigeration compressors--or in
my
>>mind submersible pumps--would have to remain O2 free to prevent corruption
>>of the extremely delicate magnet wire sheath.  O2 mixed with the oil
creates
>> an acid that attacks the windings.
>>
>
>I wasn't referring to the O2 problem but the decomposition and
contamination
>of the brushes in a trolling motor. The contact between the brushes and the
>commutator would be the problem no matter what kind of oil. Normal running
>produces a limited amount of arcing across the brush contacts. When this
path
>is contaminated with oil brush life may be reduced to a few minutes. Use of
a
>non reactive gas would be better but then no pressure compensation. I
suspect
>the motors that are filled with oil don't have brushes such as found in
>trolling motors. Refrigeration compressor motors and submersible pump
motors
>do not have brushes and are free of this problem....
>Have fun,
>Ken Martindale
>