This is a little odd for an AC motor. Typically these motors are synchronous
motors whose speed of rotation is controlled by the frequency of the voltage
source (ie 60Hz). The difference between the actual rotational speed and the
synchronous speed is called the 'slip' of the motor and this increases under
load. Reducing the impressed voltage will increase the slip
proportionally to the square of the voltage, and will reduce the breakdown
torque of the motor. At the same time, current will increase causing
heating of the windings (i squared r). Not much change in rotational speed
can be safely made using this technique. For these reasons, it is not often
recommended. (Forgive me if this a a DC motor - it wasn't completely clear
from your note)
Ed
----- Original Message -----
From: "measures" <2@vc.net>
To: "just say" <nospam4me@juno.com>; "AMPS" <amps@contesting.com>
Sent: Sunday, April 22, 2001 12:33 PM
Subject: Re: [AMPS] blowers at lower voltages
>
> >
> >
> >hello there,
> >
> >The circuit description for the Alpha 76 amplifier
> >describes the blower AC supply voltage connection
> >through a power transformer winding to "buck"
> >back the voltage to 95 vac.
> >
> >The statement is then made that the blower
> >delivers proper (near full) air flow with less noise
> >than full "normal voltage."
> >
> >Has anyone on amps measured or seen blower
> >data - spec sheets to support these statements.?
> >
> ? Blowers deliver full pressure only at full speed. Drop the RPM with
> reduced V and pressure drops exponentally. IOW, the statement seems
> bogus, Skipp.
>
> Also, Alpha uses bypass/coupling type doorknob caps in tuned circuit
> applications. I suppose that the designer did not read the Centralab
> catalog.
>
> cheers
>
> - Rich..., 805.386.3734, www.vcnet.com/measures.
> end
>
>
> --
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