Guest
What kind of ac motors are in oscillating fans and 20-inch box fans (the ones with capacitors)?
Thanks,
Michael
Thanks,
Michael
Guest
On Friday, May 6, 2016 at 1:46:44 PM UTC-7, Tim Wescott wrote:
Are the capacitors there just to start the motor, or are they permanently-split capacitor motors?
Similarly, are garage door motors capacitor-start, permanently-split, or..?
Thanks,
Michael
Are the capacitors there just to start the motor, or are they permanently-split capacitor motors?
Similarly, are garage door motors capacitor-start, permanently-split, or..?
Thanks,
Michael
C
Cydrome Leader
Guest
mrdarrett@gmail.com wrote:
> What kind of ac motors are in oscillating fans and 20-inch box fans (the ones with capacitors)?
Induction if it has a cap. There's a bunch of windings with taps for
speeds (if applicable) on a stack of laminated steel as the stator and a
cast aluminum rotor. The al casting forms the winding around the laminated
steel core of the rotor. The cap causes the lag that causes the surface of
the rotor to chase after the poles of the stator to make it spin.
> What kind of ac motors are in oscillating fans and 20-inch box fans (the ones with capacitors)?
Induction if it has a cap. There's a bunch of windings with taps for
speeds (if applicable) on a stack of laminated steel as the stator and a
cast aluminum rotor. The al casting forms the winding around the laminated
steel core of the rotor. The cap causes the lag that causes the surface of
the rotor to chase after the poles of the stator to make it spin.
Guest
On Friday, May 6, 2016 at 1:59:28 PM UTC-7, Cydrome Leader wrote:
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros and cons, and where they are typically found (among other things). Call it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four sub-categories: split phase, capacitor start, permanently split capacitor and capacitor start-capacitor run.
Notes
http://www.tcf.com/docs/fan-engineering-letters/single-phase-ac-induction-squirrel-cage-motors---fe-1100.pdf?Status=Master
http://www.allaboutcircuits.com/textbook/alternating-current/chpt-13/single-phase-induction-motors/
I'm having trouble finding examples of capacitor-start and capacitor start-capacitor run motors though.
I suspect that oscillating fans with caps are permanently-split but I'm not certain; that's why I'm asking here.
Not sure if the garage openers are capacitor-start (capacitor only starts the motor) or permanently-split (capacitor runs during the whole duration of motor operation).
If I'd been aware of the different AC motor types when in high school, that would have been very interesting (I was really only aware of shaded pole, C-frame ones back then).
Thanks,
Michael
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros and cons, and where they are typically found (among other things). Call it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four sub-categories: split phase, capacitor start, permanently split capacitor and capacitor start-capacitor run.
Notes
http://www.tcf.com/docs/fan-engineering-letters/single-phase-ac-induction-squirrel-cage-motors---fe-1100.pdf?Status=Master
http://www.allaboutcircuits.com/textbook/alternating-current/chpt-13/single-phase-induction-motors/
I'm having trouble finding examples of capacitor-start and capacitor start-capacitor run motors though.
I suspect that oscillating fans with caps are permanently-split but I'm not certain; that's why I'm asking here.
Not sure if the garage openers are capacitor-start (capacitor only starts the motor) or permanently-split (capacitor runs during the whole duration of motor operation).
If I'd been aware of the different AC motor types when in high school, that would have been very interesting (I was really only aware of shaded pole, C-frame ones back then).
Thanks,
Michael
Guest
On Friday, May 6, 2016 at 4:17:52 PM UTC-7, Tim Wescott wrote:
....
With three phases, there's no problem with starting, right?
Ok! Thanks. I'll listen for a "tick."
Another article I found mentioned the permanently-split caps have relatively low uF ratings.
Thanks!
Michael
....
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros
and cons, and where they are typically found (among other things). Call
it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four
sub-categories: split phase, capacitor start, permanently split
capacitor and capacitor start-capacitor run.
And three-phase induction motors, but that's an industrial thing so I
assume you're not going there.
With three phases, there's no problem with starting, right?
Ok! Thanks. I'll listen for a "tick."
Another article I found mentioned the permanently-split caps have relatively low uF ratings.
Thanks!
Michael
T
Tim Wescott
Guest
On Fri, 06 May 2016 12:41:13 -0700, mrdarrett wrote:
Induction motors, most likely. If there's capacitors they're "regular
old" induction motors; if there's no capacitor (not even a hidden one)
they're shaded-pole.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Induction motors, most likely. If there's capacitors they're "regular
old" induction motors; if there's no capacitor (not even a hidden one)
they're shaded-pole.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
T
Tim Wescott
Guest
On Fri, 06 May 2016 13:58:52 -0700, mrdarrett wrote:
Dunno. These would be good questions to ask on rec.crafts.metalworking,
if your reader has good killfile support and you don't mind a 1:3 signal-
noise ratio even after filtering.
AFAIK garage-door openers have switchable capacitors -- I'm pretty sure
that's how they reverse direction.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Dunno. These would be good questions to ask on rec.crafts.metalworking,
if your reader has good killfile support and you don't mind a 1:3 signal-
noise ratio even after filtering.
AFAIK garage-door openers have switchable capacitors -- I'm pretty sure
that's how they reverse direction.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
T
Tim Wescott
Guest
On Fri, 06 May 2016 14:11:34 -0700, mrdarrett wrote:
And three-phase induction motors, but that's an industrial thing so I
assume you're not going there.
If your furnace is old enough, look at its blower motor. Just about any
single-phase AC machine of 1/4 horsepower or more is going to be one of
the two. If you hear it "tick" once as it spins down you're hearing the
start capacitor switch engaging.
I suspect you're right, but do not know for sure. Capacitor-start
requires a centrifugal switch, which adds cost and impacts reliability.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
On Friday, May 6, 2016 at 1:59:28 PM UTC-7, Cydrome Leader wrote:
mrdarrett@gmail.com wrote:
What kind of ac motors are in oscillating fans and 20-inch box fans
(the ones with capacitors)?
Induction if it has a cap. There's a bunch of windings with taps for
speeds (if applicable) on a stack of laminated steel as the stator and
a cast aluminum rotor. The al casting forms the winding around the
laminated steel core of the rotor. The cap causes the lag that causes
the surface of the rotor to chase after the poles of the stator to make
it spin.
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros
and cons, and where they are typically found (among other things). Call
it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four
sub-categories: split phase, capacitor start, permanently split
capacitor and capacitor start-capacitor run.
And three-phase induction motors, but that's an industrial thing so I
assume you're not going there.
If your furnace is old enough, look at its blower motor. Just about any
single-phase AC machine of 1/4 horsepower or more is going to be one of
the two. If you hear it "tick" once as it spins down you're hearing the
start capacitor switch engaging.
I suspect you're right, but do not know for sure. Capacitor-start
requires a centrifugal switch, which adds cost and impacts reliability.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
R
Rheilly Phoull
Guest
On 7/05/2016 7:43 AM, mrdarrett@gmail.com wrote:
where more hp is required, like air compressors.
An example of cap start-cap run is usually found on single phase motorsOn Friday, May 6, 2016 at 4:17:52 PM UTC-7, Tim Wescott wrote:
...
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros
and cons, and where they are typically found (among other things). Call
it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four
sub-categories: split phase, capacitor start, permanently split
capacitor and capacitor start-capacitor run.
And three-phase induction motors, but that's an industrial thing so I
assume you're not going there.
With three phases, there's no problem with starting, right?
I'm having trouble finding examples of capacitor-start and capacitor
start-capacitor run motors though.
If your furnace is old enough, look at its blower motor. Just about any
single-phase AC machine of 1/4 horsepower or more is going to be one of
the two. If you hear it "tick" once as it spins down you're hearing the
start capacitor switch engaging.
Ok! Thanks. I'll listen for a "tick."
I suspect that oscillating fans with caps are permanently-split but I'm
not certain; that's why I'm asking here.
I suspect you're right, but do not know for sure. Capacitor-start
requires a centrifugal switch, which adds cost and impacts reliability.
Another article I found mentioned the permanently-split caps have relatively low uF ratings.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Thanks!
Michael
where more hp is required, like air compressors.
B
Baron
Guest
Tim Wescott prodded the keyboard with:
My garage door motor has two identical windings with a capacitor
between one end of each winding. The other end of the windings being
connected together. The supply goes to the common wire and one end of
the capacitor. Or the other end of the capacitor to reverse it.
Essentially a centre tapped winding with a capacitor across it.
--
Best Regards:
Baron.
My garage door motor has two identical windings with a capacitor
between one end of each winding. The other end of the windings being
connected together. The supply goes to the common wire and one end of
the capacitor. Or the other end of the capacitor to reverse it.
Essentially a centre tapped winding with a capacitor across it.
--
Best Regards:
Baron.
Guest
On Fri, 6 May 2016 12:41:13 -0700 (PDT), mrdarrett@gmail.com wrote:
If the fan is fairly small then the motor is most likely a permanent
capacitor run type. These types of motors use the cap for phase
shifting one winding in order for the motor to self start. Since
single phase motors wired this way have low starting torque they can
work well for fans but are not good for uses like garage door openers.
If the fan blades are really hard to turn then the cap will be used
just for starting and will then be switched out of the circuit. Most
motors made this way will have centrifugal starting switches and you
can hear them working when the motor is cycled on and off.
Eric
Greetings Michael,
If the fan is fairly small then the motor is most likely a permanent
capacitor run type. These types of motors use the cap for phase
shifting one winding in order for the motor to self start. Since
single phase motors wired this way have low starting torque they can
work well for fans but are not good for uses like garage door openers.
If the fan blades are really hard to turn then the cap will be used
just for starting and will then be switched out of the circuit. Most
motors made this way will have centrifugal starting switches and you
can hear them working when the motor is cycled on and off.
Eric
Guest
On Saturday, May 7, 2016 at 9:45:34 AM UTC-7, et...@whidbey.com wrote:
Thanks to all who replied.
So, slow startup, like ceiling fans, have a permanent run cap, then?
That reminds me. The 3/4-hp garbage disposal gives a nice click when winding down.
Michael
Thanks to all who replied.
So, slow startup, like ceiling fans, have a permanent run cap, then?
That reminds me. The 3/4-hp garbage disposal gives a nice click when winding down.
Michael
Guest
On Sun, 8 May 2016 22:47:57 -0700 (PDT), mrdarrett@gmail.com wrote:
are other designs, like shaded pole motors. Shaded pole motors can be
useful for fans because even though they are not very effecient they
can be speed controlled by changing the voltage, unlike the typical
split phase induction motor. Shaded pole motors draw pretty much the
same current when stalled as when running, so slowing them down
doesn't make them overheat if they don't depend on fan cooling. Split
phase motors though will draw much more current, if available, in an
attempt to speed up when the voltage is lowered and RPM drops. Which
is why they can be overheated by brownout situations.
Eric
If there is a cap then yes, most likely permanent run cap. But there
are other designs, like shaded pole motors. Shaded pole motors can be
useful for fans because even though they are not very effecient they
can be speed controlled by changing the voltage, unlike the typical
split phase induction motor. Shaded pole motors draw pretty much the
same current when stalled as when running, so slowing them down
doesn't make them overheat if they don't depend on fan cooling. Split
phase motors though will draw much more current, if available, in an
attempt to speed up when the voltage is lowered and RPM drops. Which
is why they can be overheated by brownout situations.
Eric
D
default
Guest
On Sun, 8 May 2016 22:47:57 -0700 (PDT), mrdarrett@gmail.com wrote:
All the ceiling fans I've tinkered with do have caps and a lot of
poles so they can turn slowly. Judging from how long it takes for
them to come up to speed, it may be that capacitor phase shifting is
quieter and lots more efficient.
And Yeah, that click is probably the centrifugal switch. They put
springs and such in there so the switch, when it changes state, does
so with alacrity and doesn't dilly dally drawing an arc between the
contacts.
All the ceiling fans I've tinkered with do have caps and a lot of
poles so they can turn slowly. Judging from how long it takes for
them to come up to speed, it may be that capacitor phase shifting is
quieter and lots more efficient.
And Yeah, that click is probably the centrifugal switch. They put
springs and such in there so the switch, when it changes state, does
so with alacrity and doesn't dilly dally drawing an arc between the
contacts.
T
Tim Wescott
Guest
On Tue, 10 May 2016 10:47:35 -0400, default wrote:
As opposed to shaded-pole? Possibly -- or it may be that trying to make
a multi-pole shaded-pole motor gets mechanically complex.
I'm guessing, but building the thing so that it'll start up slowly
without burning up probably involves winding the stator so that it has a
lot of leakage inductance -- that'll give you a more or less constant-
torque motor that's not burning up energy in resistance.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
I'm looking for work -- see my website!
As opposed to shaded-pole? Possibly -- or it may be that trying to make
a multi-pole shaded-pole motor gets mechanically complex.
I'm guessing, but building the thing so that it'll start up slowly
without burning up probably involves winding the stator so that it has a
lot of leakage inductance -- that'll give you a more or less constant-
torque motor that's not burning up energy in resistance.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
I'm looking for work -- see my website!
C
Cydrome Leader
Guest
mrdarrett@gmail.com wrote:
correct. There are three phases, out of phase so there something for the
rotor to chase around. With single phase there isn't a rotating component
between the phases (since there is only one) to get the motor going. The
extra cap or shunted windings create the other force to allow rotation.
On Friday, May 6, 2016 at 4:17:52 PM UTC-7, Tim Wescott wrote:
...
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros
and cons, and where they are typically found (among other things). Call
it OCD-therapy if you like
Within the class of AC Induction Motor, I see there are four
sub-categories: split phase, capacitor start, permanently split
capacitor and capacitor start-capacitor run.
And three-phase induction motors, but that's an industrial thing so I
assume you're not going there.
With three phases, there's no problem with starting, right?
correct. There are three phases, out of phase so there something for the
rotor to chase around. With single phase there isn't a rotating component
between the phases (since there is only one) to get the motor going. The
extra cap or shunted windings create the other force to allow rotation.
Guest
On Tuesday, May 10, 2016 at 9:40:29 AM UTC-7, Tim Wescott wrote:
That reminds me... the fountain pump motor: what kind of motor would this be? A submerged shaded pole..?
Typical rotors look like these. Are they really magnets?
http://www.worldbid.com/export-suppliers-catalog.htm?product=fountain-pump-rotor-magnets&page=1
Thanks,
Michael
That reminds me... the fountain pump motor: what kind of motor would this be? A submerged shaded pole..?
Typical rotors look like these. Are they really magnets?
http://www.worldbid.com/export-suppliers-catalog.htm?product=fountain-pump-rotor-magnets&page=1
Thanks,
Michael
M
Michael A. Terrell
Guest
mrdarrett@gmail.com wrote:
That could be a 'Potential Relay', instead. They are common on deep
well pumps, and I've seen them on power tools with a 1/2HP motor.
Emerson loved them, when the built the various models of direct drive
Craftsman table saws.
--
Never piss off an Engineer!
They don't get mad.
They don't get even.
They go for over unity! ;-)
That could be a 'Potential Relay', instead. They are common on deep
well pumps, and I've seen them on power tools with a 1/2HP motor.
Emerson loved them, when the built the various models of direct drive
Craftsman table saws.
--
Never piss off an Engineer!
They don't get mad.
They don't get even.
They go for over unity! ;-)
Guest
On Friday, May 6, 2016 2:11PM, mdarrett wrote:
Check out a couple of HVAC books. They have great illustrations. Some might even show schematics of hand dryers that you see in bathrooms.
On Friday, May 6, 2016 at 1:59:28 PM UTC-7, Cydrome Leader wrote:
mrda...@gmail.com wrote:
What kind of ac motors are in oscillating fans and 20-inch box fans
(the ones with capacitors)?
Induction if it has a cap. There's a bunch of windings with taps for
speeds (if applicable) on a stack of laminated steel as the stator and
a cast aluminum rotor. The al casting forms the winding around the
laminated steel core of the rotor. The cap causes the lag that causes
the surface of the rotor to chase after the poles of the stator to make
it spin.
(facepalm) ok let me step back a bit and explain.
I'm putting together a spreadsheet of various motor types, their pros
and cons, and where they are typically found (among other things). Call
it OCD-therapy if you like
Check out a couple of HVAC books. They have great illustrations. Some might even show schematics of hand dryers that you see in bathrooms.