[Boatanchors] Need magnetic shield for shaded pole motor

[J. Forster]

Insulating the shield from the motor frame is probably a good idea, but
not for the shielding effect. If the motor has exposed laminations, a
conductive shield could short some laminations together, causing eddy
currents.

The shiels does not need to be grounded. It is basically a shorted turn;
not an electrostatic shield (which would need grounding).

-John

===============


> And if I recall right, the copper shield should be electrically insulated
> from the motor frame where it wraps around it, but will need to have a
> lead to ground. Is that right? Hope he can give that a try and that it
> works.
>
>
>    Wayne
>
>
>
>  -----Original Message-----
>  From: J. Forster <jfor at quikus.com>
>  To: hwhall <hwhall at compuserve.com>
>  Cc: boatanchors <boatanchors at mailman.qth.net>
>  Sent: Fri, Jan 3, 2014 11:37 am
>  Subject: Re: [Boatanchors] Need magnetic shield for shaded pole motor
>
>  Certainly worth a try. If ventilation is an issue, copper window screen,
>  soldered alond the whole seam though.
>
>  -John
>
>  ============
>
>  > Sounds like it would be an easy experiment to wrap some copper sheet
>  > around the motor frame and tack solder the ends. Might do the same
> mag
>  > field "shorting" that the copper accomplished for those
> transformers.
>  >
>  >
>  >  Wayne
>  >
>  >
>  >
>  > -----Original Message-----
>  > From: J. Forster <jfor at quikus.com>
>  > To: rbethman <rbethman at comcast.net>
>  > Cc: boatanchors <boatanchors at mailman.qth.net>
>  > Sent: Thu, Jan 2, 2014 12:45 pm
>  > Subject: Re: [Boatanchors] Need magnetic shield for shaded pole
> motor
>  >
>  > The layers of copper inside transformers are for electrostatic
> shielding
>  > between windings. Not magnetic. They are never connected from start
> to
>  > frinish, because that would be a shorted turn. They're entirely
>  > capacitive.
>  >
>  > Some transformers have a copper band wrapped around the outside of
> the
>  > core, with beginning soldered to the end of the turn. That copper
> layer is
>  > for mahnetic shielding, due to eddy currents.
>  >
>  > -John
>  >
>
>
>
>
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