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Re: GBlist: Variable speed drives
In a message dated 97-04-18 15:25:18 EDT,
Marc.J.Rosenbaum@valley.net (Marc J. Rosenbaum) writes:
> I am trying to learn about the best way to vary substantially the
> air flow in a current project. It is possible that the central ventilation
> system ( which includes enthalpic recovery and deep dehumidification, which
> is why it is central and not distributed) will need to vary output from
> cfm down to as low as 1500-2000 cfm.
The complexity depends on the size and type of AC motor. My blower door
units have a 3/4 hp AC PSC (permanent split capacitor) motor like the kind
find on heat pump fans, and this type of motor can be controlled by an
inexpense (<$100) triac type speed control, like the ones you find in the
hardware store for overhead fan control. I use a 15 amp unit for my fans,
and this type control works
fine from 0 rpm to max rpm. The manual triac controls are available from
catalogs like WW Grainger (up to 10 amps) , and I have found a way to modify
this type of control so that it can be controlled from a PC Windows program.
I notice that Dwyer has a low cost ($69) electronic fan speed control
that works with 0-10 vdc input and controls AC motors up to 10 amps. See
part number FC-1000. I have not actually seen it.
I hope this is helpful. Are you in VA? The infiltec factory is in
Infiltec Air Leakage Control
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