Running a 1/4 hp 220 VAC condenser fan motor on 110 VAC

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From: alt.engineering.electrical
Depends on the fan motor really, I have run my furnace fan motor on reduced voltage to keep air moving about the house and through the electrostatic air cleaner. If its a belt drive affair I wouldnt run it on 120v however most direct drive motors are series poled motors meaning 6 or 8 poles are switched in and out for diffrent speeds eg 4 poles for 1750RPM no load speed.
Mine has been running on a switch relay for years switching to high speed 240v for demand then switching one side down via SPDT relay and moving one side down to neutral to slow the motor when the stack temp drops below the cutoff point. Havnt replaced the motor yet in 17 years now and I have been running the switching relay since I installed the heating plant, only oil the bearings a little more often.
Word of caution: If its a capacitor start motor I wouldnt reduce the voltage, the start winding will overheat.
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I have a capacitor RUN motor not a capacitor START motor.
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Exactly!!! You are trying to lump *ALL* motors in one big pile. Sure you can run a DC motor at half voltage and it will run...granted with reduced horsepower and higher amp draw, and a 240v PSC fan motor will run *briefly* at 120v and 1/10 of its rated speed. Again, why would you want to do it ON PURPOSE??

I wouldn't even think of trying to run a PSC motor at half voltage...why would you want to?? its counter-productive, and not what the manufacturing engineers designed it for.

A "compressor" doesn't have a fan.....a "condenser" does.

I'm not a motor design engineer, but I do know enough to know when somebody is trying to feed me a Twinky filled with something I don't want to step in. Sorry, I'm not bitin on it.
You never did answer my question.... what class are you taking that you need this information??
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Noon-Air wrote:

Read the post from an electgrical engineer above your post. He was talking about a 220 VAC motor. 17 YEARS enough proof?
A "compressor" is name of the box in which the compresser and the fan is housed.
It is good the be exacting. (but I think you knew what I meant).
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On 12 Oct 2006 07:38:03 -0700, snipped-for-privacy@aaronj.com wrote:

To EVERYONE: I think you can see from the line above that you are all dealing with a retard. Now he wants to argue that an outdoor cooling unit is called a compressor and not a condenser!!! He has trolled here long enough. Say goodbye to this Butt-Fuck. Bubba

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.

Cooling unit?
Oh! The thing.
It doesn't matter if I called you a genius, you are the opposite.
Calling each other names is what this thread enjoys, not learning a damn thing.....
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PLONK! you are stewed

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Learned that my killfile still works.....
*PLONK*
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"Noon-Air" wrote:

giggle ! who even reads these fucking morons? Oh I may read 1 or 2 of their first posts, after that why bother? I'm going to learn from the tech's and pro's who populate the ng, and most of the rest are worse than a waste of time.
on the other hand, if I had a money making website in my tagline something like click here to feed a homeless pussy, well yeah, I might wanna post a helluva lot more....know what I mean? lol
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Ask A Scientist Physics Archive
Question - I am confused about the concept of 'back emf'. Have you got a clear, concise and logical explanation of just what it is? ------------------------------------------------ Hi, Ben !!
Well, as you probably already heard before, the back-emf is the same as counter emf (cemf). It is a voltage produced in a conductor that tends to neutralize the present voltage. It is a phenomenon that always tends towards the contrary of what happens!! Lets suppose: if lines of a magnetic field are cut by a conductor, than a voltage is generated in this conductor, which causes a current of electrons to flow in one direction. At the same time, like trying to avoid this, ANOTHER voltage is created that tends to neutralize this effect, and it forces the electrons to flow in the contrary direction. As you know, the back-emf is directly pro- portional to the velocity of the magnetic field. It is proportional to the relative motion between them.
I am sure that you know all of this. But, to give you an example, think of a wire with a switch. Suppose the electrons are running from a direction into another and suddenly, you open the switch. What happens?? Well, when electrons run, they give rise to a magnetic field. When you open the switch, the electrons should stop their flow. But - as a kind of inertial action - they try to continue the flow, and ionize the air, in an electric arc to find its way. Or let it be, the originally initial magnetic field, in a circumference around the wire, changes its sense, and try to avoid stopping the original flow. It is possible to see this in an oscilloscope, as a negative peak in certain experiences where you make use of a coil and - abruptely - stops the electron flow.
I know you know all of this. But, that is it!!! It is the way things are. Just try to answer this question: what is electrical charge? Why is that we have positive and negative charges?? Answer : nobody knows it!!! We must accept this condition!!! It belongs to the laws of the universe, since the big bang created it like as it is.
Just to speak a little bit more about this subject, you know that when an electrical induction "squirrel" motor runs, you have a magnetic field that circulates around the squirrel. There is a speed difference between them, what in turn generates a voltage and a force appears, which drives the "squirrel". A back-emf also appears, which lowers the net electric electron flow. The current through a rotating electric motor is greatly reduced because of this back-emf and if you avoid the moviment of the rotor, the current should be so large that could damage the equipment.
http://www.newton.dep.anl.gov/askasci/phy00/phy00351.htm
Which prooves the point that BOTH dc armature and ac rotor motors have back EMF!
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