ceiling fan buzzing

[KR]

On Jul 23, 10:18 pm, klem kedidelhopper <captainvideo462...@gmail.com>
wrote:

On Jul 22, 8:44 am, all2...@spambog.com (Wolfgang Allinger) wrote:



 On 19 Jul 11 at group /sci/electronics/repair in article
 <wb_wildb...@XSPAMyahoo.com>  (Wild_Bill)  wrote:

Much depends upon what type of motor is in the ceiling fan. There are
more than one type of AC motors without brushes.

Klem/Lenny hasn't revealed what type of AC motor he's referring to..
nor anything specific regarding the "generic" controller that wasn't
supplied with the fan.

Here in PY there are lots of ceiling fans from Wahson/China.

230V/50Hz

They use a separate autotransformer in an aluminium housing (15x9x4 cm)  
as controller.

It is in series with the motor and has 7 taps and a turning switch with  
weird numbered positions from 0 = off and 1=max ... 7=slowest speed!
The motor so gets between 230V and down to some 80V.

My 5 Wahsons did not buzzing, even in slowest speed.

However I have 2 fans (also made in china) with no external controller  
but a small hanging line which switches between 3 different speeds by  
taping different positions in the motor winding. They both are buzzing  
in speeds below max. I think thats in the remaining active sectors of  
the winding.

None of these motors have brushes.

Saludos Wolfgang
 --
Meine 7 Sinne:
Unsinn, Schwachsinn, Blödsinn, Wahnsinn, Stumpfsinn, Irrsinn, Lötzinn.
Wolfgang Allinger   Paraguay             reply Adresse gesetzt !
ca. 15h00..21h00 MEZ  SKYPE:wolfgang.allinger

I  would like to try the trick with the capacitor in series with the
slowest tap on the speed control however I am a bit unclear as to  how
to "size" the capacitor. By "size" I mean that it seems like if the
motor draws one amp for example, (and I will confirm that first), I
will need a capacitor that can handle more than that amount of current
flowing through it. I remember dealing with this sort of thing in
electronics school, but admittedly that was a very long time ago and
I've forgotten how to work this out.

For instance, I have a 4uf 250V AC capacitor that I would like to try.
This part is designed for motor starting. This is a fairly large
capacitor. The control box measures approximately 8" x 6" X 3". Most
of that space is taken up by the switch and transformer. There would
not be room inside for anything this large. Or do I need to use
anything this large? Thanks, Lenny

Took a look inside a controller today, they have 1.8UF and 3.6UF (at
50hz) capacitors (motor was labelled 65w)

Another thing you could to, if you have access to someone who is
reasonably accurate in metal folding, is to fold the fan
blades down a little bit more to change the pitch. (alternately you
might try packing washers between the blade and the motor under the
mounting screws to tilt it slightly more - dont know if it would work
but worth a try)

A friend found that out the hard way years back when unknowingly put 4
blades meant
for a 3 blade fan onto a 4 blade fan body and nearly drove himself mad
trying to work out why he couldnt get it to go fast enough.
He had picked up several fans and a box of blades free from a place
that was being renovated and just picked out 4 blades that looked the
same.

It was a very small difference in blade angle, but knocked off an
enormous amount of speed

 

[klem kedidelhopper]

On Jul 25, 6:28 am, KR <kenreed1...@gmail.com> wrote:

On Jul 23, 10:18 pm, klem kedidelhopper <captainvideo462...@gmail.com
wrote:



On Jul 22, 8:44 am, all2...@spambog.com (Wolfgang Allinger) wrote:

 On 19 Jul 11 at group /sci/electronics/repair in article
 <wb_wildb...@XSPAMyahoo.com>  (Wild_Bill)  wrote:

Much depends upon what type of motor is in the ceiling fan. There are
more than one type of AC motors without brushes.

Klem/Lenny hasn't revealed what type of AC motor he's referring to..
nor anything specific regarding the "generic" controller that wasn't
supplied with the fan.

Here in PY there are lots of ceiling fans from Wahson/China.

230V/50Hz

They use a separate autotransformer in an aluminium housing (15x9x4 cm)  
as controller.

It is in series with the motor and has 7 taps and a turning switch with  
weird numbered positions from 0 = off and 1=max ... 7=slowest speed!
The motor so gets between 230V and down to some 80V.

My 5 Wahsons did not buzzing, even in slowest speed.

However I have 2 fans (also made in china) with no external controller  
but a small hanging line which switches between 3 different speeds by  
taping different positions in the motor winding. They both are buzzing  
in speeds below max. I think thats in the remaining active sectors of  
the winding.

None of these motors have brushes.

Saludos Wolfgang
 --
Meine 7 Sinne:
Unsinn, Schwachsinn, Blödsinn, Wahnsinn, Stumpfsinn, Irrsinn, Lötzinn.
Wolfgang Allinger   Paraguay             reply Adresse gesetzt !
ca. 15h00..21h00 MEZ  SKYPE:wolfgang.allinger

I  would like to try the trick with the capacitor in series with the
slowest tap on the speed control however I am a bit unclear as to  how
to "size" the capacitor. By "size" I mean that it seems like if the
motor draws one amp for example, (and I will confirm that first), I
will need a capacitor that can handle more than that amount of current
flowing through it. I remember dealing with this sort of thing in
electronics school, but admittedly that was a very long time ago and
I've forgotten how to work this out.

For instance, I have a 4uf 250V AC capacitor that I would like to try.
This part is designed for motor starting. This is a fairly large
capacitor. The control box measures approximately 8" x 6" X 3". Most
of that space is taken up by the switch and transformer. There would
not be room inside for anything this large. Or do I need to use
anything this large? Thanks, Lenny

Took a look inside a controller today, they have 1.8UF and 3.6UF (at
50hz) capacitors  (motor was labelled 65w)

Another thing you could to, if you have access to someone who is
reasonably accurate in metal folding, is to fold the fan
blades down a little bit more to change the pitch. (alternately you
might try packing washers between the blade and the motor under the
mounting screws to tilt it slightly more - dont know if it would work
but worth a try)

A friend found that out the hard way years back when unknowingly put 4
blades meant
for a 3 blade fan onto a 4 blade fan body and nearly drove himself mad
trying to work out why he couldnt get it to go fast enough.
He had picked up several fans and a box of blades free from a place
that was being renovated and just picked out 4 blades that looked the
same.

It was a very small difference in blade angle, but knocked off an
enormous amount of speed

But wouldn't that also load the motor more than it should be? Lenny

 

[KR]

On Jul 26, 12:28 am, klem kedidelhopper <captainvideo462...@gmail.com>
wrote:

On Jul 25, 6:28 am, KR <kenreed1...@gmail.com> wrote:



On Jul 23, 10:18 pm, klem kedidelhopper <captainvideo462...@gmail.com
wrote:

On Jul 22, 8:44 am, all2...@spambog.com (Wolfgang Allinger) wrote:

 On 19 Jul 11 at group /sci/electronics/repair in article
 <wb_wildb...@XSPAMyahoo.com>  (Wild_Bill)  wrote:

Much depends upon what type of motor is in the ceiling fan. There are
more than one type of AC motors without brushes.

Klem/Lenny hasn't revealed what type of AC motor he's referring to...
nor anything specific regarding the "generic" controller that wasn't
supplied with the fan.

Here in PY there are lots of ceiling fans from Wahson/China.

230V/50Hz

They use a separate autotransformer in an aluminium housing (15x9x4 cm)  
as controller.

It is in series with the motor and has 7 taps and a turning switch with  
weird numbered positions from 0 = off and 1=max ... 7=slowest speed!
The motor so gets between 230V and down to some 80V.

My 5 Wahsons did not buzzing, even in slowest speed.

However I have 2 fans (also made in china) with no external controller  
but a small hanging line which switches between 3 different speeds by  
taping different positions in the motor winding. They both are buzzing  
in speeds below max. I think thats in the remaining active sectors of  
the winding.

None of these motors have brushes.

Saludos Wolfgang
 --
Meine 7 Sinne:
Unsinn, Schwachsinn, Blödsinn, Wahnsinn, Stumpfsinn, Irrsinn, Lötzinn.
Wolfgang Allinger   Paraguay             reply Adresse gesetzt !
ca. 15h00..21h00 MEZ  SKYPE:wolfgang.allinger

I  would like to try the trick with the capacitor in series with the
slowest tap on the speed control however I am a bit unclear as to  how
to "size" the capacitor. By "size" I mean that it seems like if the
motor draws one amp for example, (and I will confirm that first), I
will need a capacitor that can handle more than that amount of current
flowing through it. I remember dealing with this sort of thing in
electronics school, but admittedly that was a very long time ago and
I've forgotten how to work this out.

For instance, I have a 4uf 250V AC capacitor that I would like to try..
This part is designed for motor starting. This is a fairly large
capacitor. The control box measures approximately 8" x 6" X 3". Most
of that space is taken up by the switch and transformer. There would
not be room inside for anything this large. Or do I need to use
anything this large? Thanks, Lenny

Took a look inside a controller today, they have 1.8UF and 3.6UF (at
50hz) capacitors  (motor was labelled 65w)

Another thing you could to, if you have access to someone who is
reasonably accurate in metal folding, is to fold the fan
blades down a little bit more to change the pitch. (alternately you
might try packing washers between the blade and the motor under the
mounting screws to tilt it slightly more - dont know if it would work
but worth a try)

A friend found that out the hard way years back when unknowingly put 4
blades meant
for a 3 blade fan onto a 4 blade fan body and nearly drove himself mad
trying to work out why he couldnt get it to go fast enough.
He had picked up several fans and a box of blades free from a place
that was being renovated and just picked out 4 blades that looked the
same.

It was a very small difference in blade angle, but knocked off an
enormous amount of speed

But wouldn't that also load the motor more than it should be?  Lenny

definitely would, but whether or not it damages the motor is another
matter.
as long as there is enough airflow around it to not let it overheat it
should be ok ?.

 

[Anon]

"klem kedidelhopper" <captainvideo462009@gmail.com> wrote in message
news:7a03555c-40f1-4dad-a286-f8b5ef0696be@c41g2000yqm.googlegroups.com...

We have a ceiling fan in our bedroom that we sometimes like to run at
very slow speed at night. The fan was purchased as new surplus many
years ago and never came with a speed control. So I have been using a
generic solid state speed controller. With this unit we are able to
take the unit down to complete "crawl" however there has always been a
slight rhythmic buzzing noise whose loudness and duty cycle are both
directly proportional to the motor speed. I know it's related to the
pulse type of control I'm using but short of just using a variac or a
rheostat for that matter, does anyone know of a method to achieve a
very slow speed without the noise?

Also this motor has no brushes and so even though its not labeled as
such I wonder if it could be a "Universal" type of motor that could
run on DC? It wouldn't take much to put a bridge and perhaps even a
filter in the electrical box ahead of the motor. I'm thinking that DC
operation could possibly be quieter. Thanks, Lenny

Klem,

First off, remove the light dimmer from the circuit. Dimmers are known to
cause hum/buzzing in ceiling fan induction motors. Ceiling fan induction
motors like sine waves. If the fan still buzzes on pure sine wave AC
current, the motor has loose/separated stator laminations or loose winding
coils on the stator; this is usually not repairable, although a good lacquer
bath could theoretically tighten it up.

The older spinner fans (especially ones that do not have a pull chain switch
to proivde the lower speeds) used a multiple tapped transformer to provide
the lower voltages. It was often too large to fit within a standard wall
switch box and was designed for surface mounting on the wall.

There are controls made specifically for ceiling fans that are incremental
(not continuously variable) that provide reduced voltages for the lower
speeds but keep the sine wave intact. Transformers are no longer used.

Using a capacitor inline with the power to provide the lower speeds is the
preferred method in fan manufacturing today. Today's fans and fan controls
use a dual stage capacitor - paired together in parallel for Medium and one
stage for Low Speed. For 120VAC 60Hz, the capacitor's rated voltage should
be at least 240VAC for the speed control capacitors. Speed capacitor values
range from 1.5ľF to 12ľF, with the most common falling between 3ľ and 5ľ.
There should be a running capacitor wired to one end of one motor winding,
probably mounted above the motor. The ľF value of this capacitor is a good
starting point for low speed from speed control capacitors.

Many "universal" ceiling fan controls use 5ľF + 5ľF or 5ľF + 6ľF dual
capacitors. This is around 2.5ľF for Medium and 5ľF or 6ľF for Low Speed.
Slowing the motor beyond the natural Low Speed range, to a "crawl" as it
were, with a large capacitor value will likely produce some harmonic noise
anyway, but should not buzz.

The numbering sequence for fan controls always starts at 1 for High Speed
because fans should always be started on High Speed then lowered to the
desired speed. (At a dead stop, the motor is an effective, coupled
inductor, add the speed capacitors and running capacitor, and it can create
voltages in the circuit higher than component ratings.)

Hope this helps
Scott
Dunedin, FL

 

[klem kedidelhopper]

On Aug 1, 5:25 pm, "Anon" <nos...@tbrr.net> wrote:

"klem kedidelhopper" <captainvideo462...@gmail.com> wrote in message

news:7a03555c-40f1-4dad-a286-f8b5ef0696be@c41g2000yqm.googlegroups.com...



We have a ceiling fan in our bedroom that we sometimes like to run at
very slow speed at night. The fan was purchased as new surplus many
years ago and never came with a speed control. So I have been using a
generic solid state speed controller. With this unit we are able to
take the unit down to complete "crawl" however there has always been a
slight rhythmic buzzing noise whose loudness and duty cycle are both
directly proportional to the motor speed. I know it's related to the
pulse type of control I'm using but short of just using a variac or a
rheostat for that matter, does anyone know of a method to achieve a
very slow speed without the noise?

Also this motor has no brushes and so even though its not labeled as
such I wonder if it could be a "Universal" type of motor that could
run on DC? It wouldn't take much to put a bridge and perhaps even a
filter in the electrical box ahead of the motor. I'm thinking that DC
operation could possibly be quieter. Thanks, Lenny

Klem,

First off, remove the light dimmer from the circuit.  Dimmers are known to
cause hum/buzzing in ceiling fan induction motors.  Ceiling fan induction
motors like sine waves.  If the fan still buzzes on pure sine wave AC
current, the motor has loose/separated stator laminations or loose winding
coils on the stator; this is usually not repairable, although a good lacquer
bath could theoretically tighten it up.

The older spinner fans (especially ones that do not have a pull chain switch
to proivde the lower speeds) used a multiple tapped transformer to provide
the lower voltages. It was often too large to fit within a standard wall
switch box and was designed for surface mounting on the wall.

There are controls made specifically for ceiling fans that are incremental
(not continuously variable) that provide reduced voltages for the lower
speeds but keep the sine wave intact.  Transformers are no longer used.

Using a capacitor inline with the power to provide the lower speeds is the
preferred method in fan manufacturing today.  Today's fans and fan controls
use a dual stage capacitor - paired together in parallel for Medium and one
stage for Low Speed.  For 120VAC 60Hz, the capacitor's rated voltage should
be at least 240VAC for the speed control capacitors. Speed capacitor values
range from 1.5ľF to 12ľF, with the most common falling between 3ľ and 5ľ.
There should be a running capacitor wired to one end of one motor winding,
probably mounted above the motor.   The ľF value of this capacitor is a good
starting point for low speed from speed control capacitors.

Many "universal" ceiling fan controls use 5ľF + 5ľF or 5ľF + 6ľF dual
capacitors.   This is around 2.5ľF for Medium and 5ľF or 6ľF for Low Speed.
Slowing the motor beyond the natural Low Speed range, to a "crawl" as it
were, with a large capacitor value will likely produce some harmonic noise
anyway, but should not buzz.

The numbering sequence for fan controls always starts at 1 for High Speed
because fans should always be started on High Speed then lowered to the
desired speed.  (At a dead stop, the motor is an effective, coupled
inductor, add the speed capacitors and running capacitor, and it can create
voltages in the circuit higher than component ratings.)

Hope this helps
Scott
Dunedin, FL

Thank you very much for the explanation Scott. That explains a great
many things. My speed controls on these fans are the large tapped
transformers exactly as you described. But now what about the current
flowing through the capacitor? Is this a concern when selecting a
capacitor for the application? Lenny

 

[Anon]

"klem kedidelhopper" <captainvideo462009@gmail.com> wrote in message
news:92c54535-b66b-42c0-813e-57214da371af@j15g2000yqf.googlegroups.com...
On Aug 1, 5:25 pm, "Anon" <nos...@tbrr.net> wrote:

"klem kedidelhopper" <captainvideo462...@gmail.com> wrote in message

news:7a03555c-40f1-4dad-a286-f8b5ef0696be@c41g2000yqm.googlegroups.com...



We have a ceiling fan in our bedroom that we sometimes like to run at
very slow speed at night. The fan was purchased as new surplus many
years ago and never came with a speed control. So I have been using a
generic solid state speed controller. With this unit we are able to
take the unit down to complete "crawl" however there has always been a
slight rhythmic buzzing noise whose loudness and duty cycle are both
directly proportional to the motor speed. I know it's related to the
pulse type of control I'm using but short of just using a variac or a
rheostat for that matter, does anyone know of a method to achieve a
very slow speed without the noise?

Also this motor has no brushes and so even though its not labeled as
such I wonder if it could be a "Universal" type of motor that could
run on DC? It wouldn't take much to put a bridge and perhaps even a
filter in the electrical box ahead of the motor. I'm thinking that DC
operation could possibly be quieter. Thanks, Lenny

Klem,

First off, remove the light dimmer from the circuit. Dimmers are known to
cause hum/buzzing in ceiling fan induction motors. Ceiling fan induction
motors like sine waves. If the fan still buzzes on pure sine wave AC
current, the motor has loose/separated stator laminations or loose winding
coils on the stator; this is usually not repairable, although a good
lacquer
bath could theoretically tighten it up.

The older spinner fans (especially ones that do not have a pull chain
switch
to proivde the lower speeds) used a multiple tapped transformer to provide
the lower voltages. It was often too large to fit within a standard wall
switch box and was designed for surface mounting on the wall.

There are controls made specifically for ceiling fans that are incremental
(not continuously variable) that provide reduced voltages for the lower
speeds but keep the sine wave intact. Transformers are no longer used.

Using a capacitor inline with the power to provide the lower speeds is the
preferred method in fan manufacturing today. Today's fans and fan controls
use a dual stage capacitor - paired together in parallel for Medium and
one
stage for Low Speed. For 120VAC 60Hz, the capacitor's rated voltage should
be at least 240VAC for the speed control capacitors. Speed capacitor
values
range from 1.5ľF to 12ľF, with the most common falling between 3ľ and 5ľ.
There should be a running capacitor wired to one end of one motor winding,
probably mounted above the motor. The ľF value of this capacitor is a good
starting point for low speed from speed control capacitors.

Many "universal" ceiling fan controls use 5ľF + 5ľF or 5ľF + 6ľF dual
capacitors. This is around 2.5ľF for Medium and 5ľF or 6ľF for Low Speed.
Slowing the motor beyond the natural Low Speed range, to a "crawl" as it
were, with a large capacitor value will likely produce some harmonic noise
anyway, but should not buzz.

The numbering sequence for fan controls always starts at 1 for High Speed
because fans should always be started on High Speed then lowered to the
desired speed. (At a dead stop, the motor is an effective, coupled
inductor, add the speed capacitors and running capacitor, and it can
create
voltages in the circuit higher than component ratings.)

Hope this helps
Scott
Dunedin, FL

Thank you very much for the explanation Scott. That explains a great
many things. My speed controls on these fans are the large tapped
transformers exactly as you described. But now what about the current
flowing through the capacitor? Is this a concern when selecting a
capacitor for the application? Lenny

Klem,

Typically ceiling fan motors pull less than 1 amp current at 120V and the
capacitors used in ceiling fans are large, metallized poly film type AC
capacitors. We've never had to consider the current with these capacitors.

Scott