Re: Central Vac overload

["hr(bob) hofmann@xxxxxxx" <hrhofmann@xxxxxxx>]

On Mar 30, 12:51=A0pm, Art Todesco <actode...@xxxxxxxxx> wrote:
> On 3/30/2010 10:45 AM, George wrote:
>
>
>
> > On 3/30/2010 7:23 AM, Robert Green wrote:
> >> Some of you might remember my question about building a silencing cabi=
net
> >> for a central vac. Well, it worked, but too well. The problem is now t=
hat
> >> if something gets stuck in the hose, we can no longer hear the immedia=
te
> >> increase in the motor load the way we used to. On occasion, the unit's
> >> motor even shuts down from the overload.
>
> >> Does anyone have any ideas how to detect the "laboring" of the motor s=
o I
> >> can sound a chime or some other alarm when something clogs the pope -
> >> I mean
> >> pipe - the Pope has enough problems of his own. (-:
>
> >> I am going to try a test today with my Kill-0-Watt meter to see if
> >> there's a
> >> substantial increase in current draw. I might be able to use a current
> >> sensor to detect the upswing and sound a chime or some other kind of
> >> warning. I don't want to shorten the life of the motor by letting the
> >> thermal overload shut it down after it has overheated.
>
> >> Thanks in advance
>
> >> --
> >> Bobby G.
>
> >> Crossposted to alt.home.repair;comp.home.automation, follow up in AHR,
> >> please!
>
> > Guess I am missing something.
>
> > If you are using it and suddenly there is no or greatly diminished
> > vacuum wouldn't that be a sufficient indicator that there is a problem?
>
> If you are using it with a motor
> operated beater brush, you really can't
> hear the loss of suction over the motor
> noise. =A0I know, both me and my wife have
> had it happen in our old house. =A0What
> can alert you is that you have to go
> over the same spot several times to pick
> up the one little crumb.- Hide quoted text -
>
> - Show quoted text -

First the OP must see if the blocked hose speeds up or slows down the
motor, and see if the current increases or decreases.

I like the suggestion of Mr. Todesco that puts a vacuum bypass on the
inlet to the motor/vacuum pump.  That guarantees you will not damage
the motor unless the spring in the bypass suddenly gets stronger or
the diaphram jams with dirt.  That is unlikely to happen.  If the
current does increase, a loop of wire through a ferrite core, with a
second coil of  many turns on the same core can generate an increased
voltage when the current thru the motor increases, if that is what is
happening.  That increased voltage could be used to do any number of
things, but that is for a different group (sci.electronics.repairor
misc).