There has to be some kind of start winding in any single phase motor.
It may be a shorted turn in a shaded pole motor ( small motor) or an high value
inductive winding for larger ones (which may stay on at all times or
disconnected after motor starts to turn). But for high torque situations you
use a capacitor in series with a lower inductance start winding to get the
motor started. The winding is used to determine the direction of rotation.
Other wise the motor may start to rotate in either direction if at all.
73
Bill wa4lav
-----Original Message-----
From: 2 <2@vc.net>
To: <W8JI@contesting.com>, "'kb9cry@attbi.com'" <kb9cry@attbi.com>, "Pete Smith
" <n4zr@contesting.com>, "Steve Katz" <stevek@jmr.com>
To: <amps@contesting.com>
Date: Mon, 22 Jul 2002 19:23:47 -0700
Subject: RE: [Amps] Muffin Fans and hot exhaust
>
>> [Steve Katz] I realize that this works to some extent; however, I
>> have been unsuccessful in quantifying actual results because the AC
>> motors run on reduced voltage have a great reduction in torque and
>> thus cannot spin well against back pressure. When I run a standard
>> 240V 125cm (4.25") "Boxer" type fan on 120V, I can stall it with the
>> tip of my finger very easily, no damage done to finger.
>
>Assuming the motor can take it, motors with start/run windings can be
>damaged when operated at low voltage, ...
Start-winding motors are used in compressors, where the motor needs to be
able to start against static gas pressure. I have never seen a blower or
fan with a start-winding.
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|