Single phase motors vs multiphase vibration

Eric, that motor would be a Permanent Capacitor motor, commonly referred to as a 2-phase motor. Other comments of the PC types were mentioned in a reply to Chuck S post, above.
WB ................
Reply to
Wild Bill
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It know dis way: The motor has two identical windings. One end of each winding is connected to the other winding. This connection is also connected to one of the two wires providing power. The other ends of the two windings are connected together with a capacitor. The remaining power wire is then connected to one side or the other of the capacitor. This determines the direction of rotation. Another way to explain it is like this: There are two windings and each winding has two ends. We'll call these W1, W2, W3,and W4. W1 and W2 are the ends of one winding, W3 and W4 the ends of the other winding. The capacitor ends we'll call C1, and C2. The power wires P1, and P2. Connect W1, W3, and P1 together. Connect C1 to W2 and C2 to W4. Now, connect P2 to the C1,W2 junction and the motor will spin one way. If P2 is connected to the C2, W4 junction the motor will spin the other way. Motors built this way run smooth but have much less starting torque. Since there is no centrifigul starting switch they can be made to run slower with lower voltage. Higher voltage will only increase torque. The motor can not attain Eric R Snow > >> The types of applications for these types motors is fairly wide. Many low >> power applications such as fans, pumps, blowers, gear head torque slow >> speeds, and others. >> >> The stators can have several different pole configurations, and this allows >> motors that attain specific speeds from an AC source. Speeds of these motors >> can vary from about 600 RPM versions to 3200 RPM models. >> >> Many manufacturers make numerous versions of the PC motors for a wide >> variety of applications.. Bodine, Dayton, Oriental Motor and many others. >> >> WB >> ............... >>
>> >>>>So even a two phase motor would eliminate the zero torque situation >>>>twice per second. >>> >>>Whats a 2 phase motor and where do you get two phase power?? >>>240V in your house is NOT 2 phase power. >>> >> >> >> >> >>
Reply to
Eric R Snow
The capacitor is connected between 2 of the 3 motor leads, and these connections stay connected that way. One of the AC line connections is made to either of the same 2 connections, one for CW, or the other for CCW rotation. This leaves one of the capacitor/stator connections floating (not connected to the AC line connections, which would be L1-L2 for 240VAC or L-N for 120VAC operation).
WB ..............
Reply to
Wild Bill
Not strictly correct, Wild Bill.
> Eric, that motor would be a Permanent Capacitor motor, commonly referred > to > as a 2-phase motor. > Other comments of the PC types were mentioned in a reply to Chuck S post, > above. > > WB > ................ >
>> >> > >> >A capacitor "start and run motor" does, in fact, have a start winding. >> >Generally, "cap. start and/or cap. run" implies a single-phase motor >> >with > a >> >start winding. The start winding is usu. wound with smaller gauge wire > than >> >the main winding and is used only temporarily during the starting > interval. >> >The start winding is separated by mechanical space upon the stator and > thus >> >is responsible for "phase shifted" sets of poles on the stator. A >> >single-phase motor starts as a 2-phase machine. A 3-phase motor started > on >> >single phase is also temporarily connected "2-phase" during start time. >> > >> >Bob Swinney >> > >> > >> Actually Bob, the motor I was thinking about does not have a start >> winding or a centrifigul switch. It has two identical windings. The >> windings are connected to each other at one end and this end is >> connected to the line. The other ends are connected to each other >> through a capacitor. Connecting the other line wire to one side of the >> cap or the other determines the rotation. So I think the motor acts >> like a two phase machine because of the phase shift provided by the >> capacitor. >> Eric >> > > > >
Reply to
Robert Swinney
Continuation of above post - not strictly correct - that'd be a capacitor run single phase motor. See Don Foreman and other's posts above.
Bob Swinney
> Not strictly correct, Wild Bill.
>> Eric, that motor would be a Permanent Capacitor motor, commonly referred >> to >> as a 2-phase motor. >> Other comments of the PC types were mentioned in a reply to Chuck S post, >> above. >> >> WB >> ................ >>
>>> >>> > >>> >A capacitor "start and run motor" does, in fact, have a start winding. >>> >Generally, "cap. start and/or cap. run" implies a single-phase motor >>> >with >> a >>> >start winding. The start winding is usu. wound with smaller gauge wire >> than >>> >the main winding and is used only temporarily during the starting >> interval. >>> >The start winding is separated by mechanical space upon the stator and >> thus >>> >is responsible for "phase shifted" sets of poles on the stator. A >>> >single-phase motor starts as a 2-phase machine. A 3-phase motor >>> >started >> on >>> >single phase is also temporarily connected "2-phase" during start time. >>> > >>> >Bob Swinney >>> > >>> > >>> Actually Bob, the motor I was thinking about does not have a start >>> winding or a centrifigul switch. It has two identical windings. The >>> windings are connected to each other at one end and this end is >>> connected to the line. The other ends are connected to each other >>> through a capacitor. Connecting the other line wire to one side of the >>> cap or the other determines the rotation. So I think the motor acts >>> like a two phase machine because of the phase shift provided by the >>> capacitor. >>> Eric >>> >> >> >> >>
Reply to
Robert Swinney
Bob, what Eric described is an AC PC or 2-phase induction motor.
I don't believe there are any other motor types that have 2 identical windings, connected, with an attached (external) capacitor, and reversed by moving the AC line connection from one capacitor/winding connection to the other capacitor/winding connection.
If there are, let us know
WB ...............
Reply to
Wild Bill
Not sure about your definition of AC PC motor ? What does PC mean ? I believe you are "seeing" a capacitor start, single-phase induction motor; maybe even a capacitor-run single-phase induction motor. There would be no need for a capacitor in a real (very old fashioned) 2-phase motor. As someone else mentioned, genuine 2-phase motors are rare, nowadays.
Bob Swinney
> Bob, what Eric described is an AC PC or 2-phase induction motor. > > I don't believe there are any other motor types that have 2 identical > windings, connected, with an attached (external) capacitor, and reversed > by > moving the AC line connection from one capacitor/winding connection to the > other capacitor/winding connection. > > If there are, let us know > > WB > ............... >
>> Not strictly correct, Wild Bill. >
>> > Eric, that motor would be a Permanent Capacitor motor, commonly >> > referred >> > to >> > as a 2-phase motor. >> > Other comments of the PC types were mentioned in a reply to Chuck S > post, >> > above. >> > >> > WB >> > ................ >> > >> >> Actually Bob, the motor I was thinking about does not have a start >> >> winding or a centrifigul switch. It has two identical windings. The >> >> windings are connected to each other at one end and this end is >> >> connected to the line. The other ends are connected to each other >> >> through a capacitor. Connecting the other line wire to one side of the >> >> cap or the other determines the rotation. So I think the motor acts >> >> like a two phase machine because of the phase shift provided by the >> >> capacitor. >> >> Eric >> >> >> > > > > >
Reply to
Robert Swinney
Bob, you and I seem to have been referring to two different types of motors, but both of them could/would be called 2-phase motors. I'm not at all familiar with 2-phase AC power available from a utility company. I've read that it has existed, and may still be available in some locations.
I didn't mean to imply that their motors required a 2-phase power source to operate them. In the two instances of both Eric and Don's motor descriptions, the motor types are AC Permanent Capacitor induction motors that operate as 2-phase motors, with the capacitor providing/creating the phase shift. These presently produced (not antique) types of motors operate on single phase AC, and don't require a 2-phase AC supply for operation. There are old versions of the PC motors around.. the design isn't new, but they're still being manufactured for many uses.
By design, the capacitor used with the single phase PC motor creates the "second phase", much in the same way that capacitors permit a 3-phase motor to be operated with single phase AC.
The characteristics of the single phase PC motors are that there are no separate start and run windings, and no centrifugal switch. Additionally, they have 2 identical windings connected together to form 3 stator connections. The capacitor is connected to 2 specific leads, and the single phase is connected to 2 of the 3 leads. These motors are typically labeled as single phase induction motors, and nearly always have a capacitor value (uF) shown on the label or plate. The capacitor is always an externally connected component AFAIK, generally not mounted under a cover attached to the motor case (like split-phase or capacitor run motors are). The capacitor value is usually in the range of 2 to 30uF for small fractional HP motors up to about 1/8 HP and has a voltage rating of 250VAC or higher. Numerous manufacturers rate and/or label their small motors in watts instead of HP, and indicate if the motor is intended for use with 50 or 60Hz.
WB ...............
Reply to
Wild Bill
Very Well, Wild Bill. Your description of a capacitor start/capacitor run motor is well taken. However it is incorrect to call a motor a "2-phase motor" unless it is designed to run on 2-phase power. I think you are describing an ordinary, capacitor run, single-phase induction motor that is designed to run on single-phase power only.
Bob Swinney
> Bob, you and I seem to have been referring to two different types of > motors, > but both of them could/would be called 2-phase motors. I'm not at all > familiar with 2-phase AC power available from a utility company. I've read > that it has existed, and may still be available in some locations. > > I didn't mean to imply that their motors required a 2-phase power source > to > operate them. > In the two instances of both Eric and Don's motor descriptions, the motor > types are AC Permanent Capacitor induction motors that operate as 2-phase > motors, with the capacitor providing/creating the phase shift. > These presently produced (not antique) types of motors operate on single > phase AC, and don't require a 2-phase AC supply for operation. > There are old versions of the PC motors around.. the design isn't new, but > they're still being manufactured for many uses. > > By design, the capacitor used with the single phase PC motor creates the > "second phase", much in the same way that capacitors permit a 3-phase > motor > to be operated with single phase AC. > > The characteristics of the single phase PC motors are that there are no > separate start and run windings, and no centrifugal switch. > Additionally, they have 2 identical windings connected together to form 3 > stator connections. The capacitor is connected to 2 specific leads, and > the > single phase is connected to 2 of the 3 leads. > These motors are typically labeled as single phase induction motors, and > nearly always have a capacitor value (uF) shown on the label or plate. The > capacitor is always an externally connected component AFAIK, generally not > mounted under a cover attached to the motor case (like split-phase or > capacitor run motors are). > The capacitor value is usually in the range of 2 to 30uF for small > fractional HP motors up to about 1/8 HP and has a voltage rating of 250VAC > or higher. > Numerous manufacturers rate and/or label their small motors in watts > instead > of HP, and indicate if the motor is intended for use with 50 or 60Hz. > > WB > ............... >
>> Not sure about your definition of AC PC motor ? What does PC mean ? >> I believe you are "seeing" a capacitor start, single-phase induction > motor; >> maybe even a capacitor-run single-phase induction motor. There would be > no >> need for a capacitor in a real (very old fashioned) 2-phase motor. As >> someone else mentioned, genuine 2-phase motors are rare, nowadays. >> >> Bob Swinney >> > > > >
Reply to
Robert Swinney
Bob, how would I identify a motor that only runs on 2-phase power by the internal characteristics, in case I would happen to encounter one?
I used to have a multi-volume set of books from the early 1900s on electrical engineering, but don't have them now. That was a fascinating resource, if anyone would happen to encounter something like that at a yard sale or flea market.
Perhaps it would be more technically accurate for me to stop referring to PC motors as 2-phase motors, but instead say that they "operate as a 2-phase motor does". The stator windings of permanent capacitor motors are both considered to be run windings. As there is no start winding (and no combination of start/run windings with a centrifugal switch), these motors have low starting torque. They are indeed single-phase only motors, as you stated.
The capacitor start/capacitor run motors that I'm familiar with are motors with 2 separate capacitors, separate start/run windings, and a centrifugal switch. These types are designed for high starting torque and heavy duty use (compressor-rated duty, for example). They have a large value capacitor for starting, and a low value capacitor for run, typically secured to the outside of the motor case under covers. While the 2 capacitor CS/CR motor design also incorporates 2 identical stator windings, it differs from the PC motor in that the PC motor has only one capacitor, no start winding and no centrifugal switch.
WB .............
Reply to
Wild Bill
I have to side with bill, Technically it is a two phase motor. It is designed to run on two phase power, with the capacitor providing the 2 phase.
To say you are correct, would make a (3 ph) motor run off of a static phase converter also a single phase motor. jk
Reply to
jk
"> Perhaps it would be more technically accurate for me to stop referring to PC
Bill, that would be absolutely correct if PC motors were not referred to as 2-phase motors. Even though operated with single-phase power, such motors do run as 2-phase machines, as you said. I'm sorry, if earlier I seemed to dispute you on this fact. In a PC motor, or a split-phase motor for that matter, the "2nd phase" is derived by virtue of the auxiliary winding and capacitor; except the ordinary split-phase machine omits the cap. The windings of PC motors are displaced from each other by 90 degrees, the same as in the very old fashioned 2-phase motors designed to run on 2 phases as delivered from the power lines. There are several variations of this scheme re. the aux. winding and capacitor. AFAIK, motors of this type have identical windings if they are designed to deliver any appreciable power - such as in AC compressors and dishwashers. One obvious advantage in appliances is the ease of reversing via external contacts.
Bob Swinney
> Bob, how would I identify a motor that only runs on 2-phase power by the > internal characteristics, in case I would happen to encounter one? > > I used to have a multi-volume set of books from the early 1900s on > electrical engineering, but don't have them now. That was a fascinating > resource, if anyone would happen to encounter something like that at a > yard > sale or flea market. > > > The capacitor start/capacitor run motors that I'm familiar with are motors > with 2 separate capacitors, separate start/run windings, and a centrifugal > switch. These types are designed for high starting torque and heavy duty > use > (compressor-rated duty, for example). > They have a large value capacitor for starting, and a low value capacitor > for run, typically secured to the outside of the motor case under covers. > While the 2 capacitor CS/CR motor design also incorporates 2 identical > stator windings, it differs from the PC motor in that the PC motor has > only > one capacitor, no start winding and no centrifugal switch. > > WB > ............. >
>> Very Well, Wild Bill. Your description of a capacitor start/capacitor >> run >> motor is well taken. However it is incorrect to call a motor a "2-phase >> motor" unless it is designed to run on 2-phase power. I think you are >> describing an ordinary, capacitor run, single-phase induction motor that > is >> designed to run on single-phase power only. >> >> Bob Swinney > > > >
Reply to
Robert Swinney

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