Re: Central Vac overload

["Existential Angst" <UNfitcat@xxxxxxxxxxxxxxx>]

"Existential Angst" <UNfitcat@xxxxxxxxxxxxxxx> wrote in message
news:4bb1efc2$0$4997$607ed4bc@xxxxxxxxx
> "Robert Green" <robert_green1963@xxxxxxxxx> wrote in message
> news:hosmv1$fp7$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> Some of you might remember my question about building a silencing cabinet
>> for a central vac.  Well, it worked, but too well.  The problem is now
>> that
>> if something gets stuck in the hose, we can no longer hear the immediate
>> 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 so 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
>
> I think what you'll find is that your killawatt will show a substantial
> DECREASE in current.  The motor is not laboring, but actually speeding up,
> as there is no air to load it.  Almost counter-intuitive, that as a vacuum
> clogs, it works less!
>
> What is likely happening is that the motor is going out on temperature
> overload, not from current, but from lack of airflow, that cools the
> motor.
>
> Still, you could use a current alarm like what Mike did, or an air flow
> switch (Graingers) in the exhaust, or even a thermostat switch somewhere
> in the exhaust, around the motor, before the motor temp overload kicks in.
>
> Probably an airflow switch in the exhaust would be the cheapest, most
> straightforward.
> You could even build this yourself with a piece of a soda can and a
> microswitch from radio shack or someplace.
>
> What I would do is connect a NO relay to the power switch (the coil of the
> relay).  Then, in series with the relay contacts, I would put a NC
> microswitch operated by the soda can flapper.
> This way, the alarm will sound if air flow stops, but not when the unit is
> off.

Oh, yeah, you could also wire this up so that a relay cuts off the motor,
and locks out, AND sounds an alarm.
--
EA



>
> --
> EA
>
>
>>
>> --
>> Bobby G.
>>
>> Crossposted to alt.home.repair;comp.home.automation, follow up in AHR,
>> please!
>>
>>
>
>