Re: Central Vac overload

[harry <haroldhrmtg@xxxxxxx>]

On Apr 4, 4:11=EF=BF=BDpm, "Josepi" <J.R...@xxxxxxxxxxxx> wrote:
> You may find the current doesn't drop significantly as the power consumpr=
ion
> does.
>
> When load is removed from sysncronous motors the power factor decreses to
> the bottom, the current stays relatively in the same ball park, depending=
 on
> motor design.
>
> If you put a Kill-a-Watt monitor on it you may a huge difference in
> consumption.
>
> "Robert Green" <robert_green1...@xxxxxxxxx> wrote in message
>
> news:hp9pkg$clo$3@xxxxxxxxxxxxxxxxxxxx"Existential Angst" <UNfit...@UNopt=
online.net> wrote in message
>
> news:4bb1efc2$0$4997$607ed4bc@xxxxxxxxx
>
> > "Robert Green" <robert_green1...@xxxxxxxxx> wrote in message
>
> <stuff snipped>
>
> > I think what you'll find is that your killawatt will show a substantial
> > DECREASE in current. =EF=BF=BDThe motor is not laboring, but actually s=
peeding up,
> > as there is no air to load it. =EF=BF=BDAlmost counter-intuitive, that =
as a vacuum
> > clogs, it works less!
>
> Exactly correct. =EF=BF=BDVery odd to see, but about 4A less when screami=
ng like a
> rocket.
>
> --
> Bobby G.

Not in the slightest odd.  It is a centrifugal pump, accelarating air
from nil speed to several hundred miles an hour.  If the air flow is
cut off, there is no air getting in to accelarate.  So it's not doing
any work except friction losses. So the motor speeds up. Electric
current reduces. Simple.  This applies to all centrifugal pumps BTW.
There is no way of determining the difference between motor running/no
hoses connected and blocked.
If the thing is cutting out, it's probably the thermal overload
because of over heating   due to the cabinet.
Portable vacuum cleaners rely on the cleaning air sucked through the
hose for cooling but central plant cannot as all the hoses may be shut
off.
Large central vacuum plants may have an induction motor (quiet
running) but the same applies, except that the motor speed varies very
little.