Cooling fans - is the AC frequency a factor?

S

Steve

Guest
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.
 
Steve <emailstevecooke@yahoo.co.uk> writes:

I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.
Click to expand...
Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
"Steve" <emailstevecooke@yahoo.co.uk> wrote in message
news:5e3ce32d-127c-428d-b085-0ee64b9456eb@8g2000hse.googlegroups.com...
On Oct 13, 2:39 am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?
Click to expand...

I didn't detect an ounce of sarcasm in Sam's reply. He answered you
matter-of-factly, and I totally agree with everything he said. Your original
post stated that the device was for the "aircraft industry", implying that it
would probably be used on or around an airplane. In retrospect, I would
certainly have deduced the same thing that Sam did.
Your original post would certainly have avoided all this if you had been more
specific about the device, and where it would be used. We could care less about
your financial arrangements with whomever you are building it.

An AC fan motor is almost certainly a synchronous type, meaning that its speed
is totally dependent on the frequency of the power source. It would likely go
up in smoke within a few seconds.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Life is like a roll of toilet paper; the closer it gets to the end, the faster
it goes.
 
On Oct 13, 2:39 am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
    sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
 Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
        | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line.  Or, you can contact me via the Feedback Form in the FAQs..
Click to expand...
I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?
 
Do you blatantly ignore the ratings on other components? You can
get away with putting too much voltage on a capacitor, or extra watts
into a resistor, but not for very long.

With an AC fan, most are designed for a limited frequency range. The
inductance and laminations and RPM are geared for a rather narrow
range.

Most likely the 60Hz fan will refuse to spin. If it does spin, it
will be way below synchronous speed and you'll get very little torque
out of it.

The traditional way out is to use a fan running off some handy DC
supply.
 
On Sun, 12 Oct 2008 16:51:29 -0700 (PDT), Steve
<emailstevecooke@yahoo.co.uk>wrote:

On Oct 13, 2:39?am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. ? I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? ?Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? ?If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
? ? sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
?Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
? ? ? ? | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. ?Or, you can contact me via the Feedback Form in the FAQs.

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?
Click to expand...
Nice attitude.
 
Steve wrote:
On Oct 13, 2:39�am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. ďż˝ I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? �Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? �If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
ďż˝ ďż˝ sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
�Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
ďż˝ ďż˝ ďż˝ ďż˝ | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. �Or, you can contact me via the Feedback Form in the FAQs.

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?
Click to expand...
He DOES know and you ARE screwing around but fortunately no one will
die from your work.

G²
 
"DaveM" <masondg4499@comcast99.net> wrote in message
news:1tCdnU_OPrxjBW_VnZ2dnUVZ_ojinZ2d@comcast.com...
"Steve" <emailstevecooke@yahoo.co.uk> wrote in message
news:5e3ce32d-127c-428d-b085-0ee64b9456eb@8g2000hse.googlegroups.com...
On Oct 13, 2:39 am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that
uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and
have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?


I didn't detect an ounce of sarcasm in Sam's reply. He answered you
matter-of-factly, and I totally agree with everything he said. Your
original post stated that the device was for the "aircraft industry",
implying that it would probably be used on or around an airplane. In
retrospect, I would certainly have deduced the same thing that Sam did.
Your original post would certainly have avoided all this if you had been
more specific about the device, and where it would be used. We could care
less about your financial arrangements with whomever you are building it.

An AC fan motor is almost certainly a synchronous type, meaning that its
speed is totally dependent on the frequency of the power source. It would
likely go up in smoke within a few seconds.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters
in the address)

Life is like a roll of toilet paper; the closer it gets to the end, the
faster it goes.
Click to expand...
Seconded on every comment. Sam's replies and scribblings are well respected
on this group, and if you can't listen without getting unnecessarily arsey,
then perhaps you are asking your question in the wrong place ...

Arfa
 
On Sun, 12 Oct 2008 16:51:29 -0700 (PDT), Steve
<emailstevecooke@yahoo.co.uk> wrote:

On Oct 13, 2:39 am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
    sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
 Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
        | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line.  Or, you can contact me via the Feedback Form in the FAQs.

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please.

As you do not know if it will work or not why bother
replying?
Click to expand...
He did answer your question, it won't work.
 
On Sun, 12 Oct 2008 22:37:29 -0700 (PDT), stratus46@yahoo.com wrote:

Steve wrote:
On Oct 13, 2:39?am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. ? I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? ?Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? ?If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
? ? sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
?Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
? ? ? ? | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. ?Or, you can contact me via the Feedback Form in the FAQs.

I am not 'screwing around' with a 'will it work' solution and the
equipment is not for on aircraft use. It is a simple bench test unit
that only has a 115V 400Hz supply. As I am not being paid for the
making of it I wish to see if I can use what equipment is available,
rather than purchase bits I may not get refunded for; so less of the
sarcasm please. As you do not know if it will work or not why bother
replying?

He DOES know and you ARE screwing around but fortunately no one will
die from your work.
Click to expand...
Sadly, you don't know that. Since the OP has been less than honest,
can't read replies, who knows what he's doing.
 
On Tue, 14 Oct 2008 13:15:28 -0700 (PDT), z <gzuckier@snail-mail.net>
wrote:

On Oct 12, 7:32 pm, Steve <emailsteveco...@yahoo.co.uk> wrote:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

i'm pretty sure a 50/60 cycle fan wouldn't work; i agree with the guy
who suggested a DC one. plenty of DC muffin fans around, and DC is
universally producable. on the other hand, i don't know anything about
airplane equipment, although i still have an old war surplus 400 hz
motor/generator knocking around somewhere.
I once ran some ham equipment (which used a linear 12v power supply)
Click to expand...
from a 400 Hz surplus generator. It worked well. The only way I
could tell was instead of hearing a slight 60 Hz hum in the receive
audio, I heard a slight 400 Hz hum. I felt like I was listening to
flight attendant announcements in a DC-9. To this day, the PA system
in DC-9's have that hum. By "to this day", I mean flying in an
AirTran Boeing 717 which was the final configuration of the DC-9
before they went out of production. Sorry. Just rambling... None
of this has anything to do with running an AC fan.
 
On Oct 12, 7:32 pm, Steve <emailsteveco...@yahoo.co.uk> wrote:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.
Click to expand...
i'm pretty sure a 50/60 cycle fan wouldn't work; i agree with the guy
who suggested a DC one. plenty of DC muffin fans around, and DC is
universally producable. on the other hand, i don't know anything about
airplane equipment, although i still have an old war surplus 400 hz
motor/generator knocking around somewhere.
 
"Steve" <emailstevecooke@yahoo.co.uk> schreef in bericht
news:5e3ce32d-127c-428d-b085-0ee64b9456eb@8g2000hse.googlegroups.com...
On Oct 13, 2:39 am, s...@seas.upenn.edu (Samuel M. Goldwasser) wrote:
Steve <emailsteveco...@yahoo.co.uk> writes:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

Get a proper 400 Hz fan or run a DC fan off a DC supply.

If there's anyplace you don't want to be screwing around with
"will it work" solutions, it's the aircraft industry!

And the answer is: It almost certainly won't work.

--
sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/
Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
Click to expand...
| I am not 'screwing around' with a 'will it work' solution and the
| equipment is not for on aircraft use. It is a simple bench test unit
| that only has a 115V 400Hz supply. As I am not being paid for the
| making of it I wish to see if I can use what equipment is available,
| rather than purchase bits I may not get refunded for; so less of the
| sarcasm please. As you do not know if it will work or not why bother
| replying?

1. Learn to read.
2. Learn to ask questions.
3. Learn about usenet.

For 1. you're on your own.
For 2. you will have to provide the relevant information to get a usefull
answer.
For 3. answers are for free but you cannot make demands.

As for the original question, read Sams answer.

petrus bitbyter
 
On Tue, 14 Oct 2008 17:35:17 -0400, greenpjs <greenpjs@neo.rr.com> put
finger to keyboard and composed:

On Tue, 14 Oct 2008 13:15:28 -0700 (PDT), z <gzuckier@snail-mail.net
wrote:

On Oct 12, 7:32 pm, Steve <emailsteveco...@yahoo.co.uk> wrote:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

i'm pretty sure a 50/60 cycle fan wouldn't work; i agree with the guy
who suggested a DC one. plenty of DC muffin fans around, and DC is
universally producable. on the other hand, i don't know anything about
airplane equipment, although i still have an old war surplus 400 hz
motor/generator knocking around somewhere.
I once ran some ham equipment (which used a linear 12v power supply)
from a 400 Hz surplus generator. It worked well. The only way I
could tell was instead of hearing a slight 60 Hz hum in the receive
audio, I heard a slight 400 Hz hum. I felt like I was listening to
flight attendant announcements in a DC-9. To this day, the PA system
in DC-9's have that hum. By "to this day", I mean flying in an
AirTran Boeing 717 which was the final configuration of the DC-9
before they went out of production. Sorry. Just rambling... None
of this has anything to do with running an AC fan.
Click to expand...
While we're rambling, I wonder how a mains frequency digital flip
clock would run on a 400Hz supply, assuming it survived the
experience. I reckon it would make an excellent bundy clock. Here in
Australia we'd cut our working days to one hour ... just enough time
for lunch. Time would fly.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Franc Zabkar <fzabkar@iinternode.on.net> writes:

On Tue, 14 Oct 2008 17:35:17 -0400, greenpjs <greenpjs@neo.rr.com> put
finger to keyboard and composed:

On Tue, 14 Oct 2008 13:15:28 -0700 (PDT), z <gzuckier@snail-mail.net
wrote:

On Oct 12, 7:32 pm, Steve <emailsteveco...@yahoo.co.uk> wrote:
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply.   I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work?  Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency?  If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.

i'm pretty sure a 50/60 cycle fan wouldn't work; i agree with the guy
who suggested a DC one. plenty of DC muffin fans around, and DC is
universally producable. on the other hand, i don't know anything about
airplane equipment, although i still have an old war surplus 400 hz
motor/generator knocking around somewhere.
I once ran some ham equipment (which used a linear 12v power supply)
from a 400 Hz surplus generator. It worked well. The only way I
could tell was instead of hearing a slight 60 Hz hum in the receive
audio, I heard a slight 400 Hz hum. I felt like I was listening to
flight attendant announcements in a DC-9. To this day, the PA system
in DC-9's have that hum. By "to this day", I mean flying in an
AirTran Boeing 717 which was the final configuration of the DC-9
before they went out of production. Sorry. Just rambling... None
of this has anything to do with running an AC fan.

While we're rambling, I wonder how a mains frequency digital flip
clock would run on a 400Hz supply, assuming it survived the
experience. I reckon it would make an excellent bundy clock. Here in
Australia we'd cut our working days to one hour ... just enough time
for lunch. Time would fly.
Click to expand...
These are synchronous motor-driven.

Better to hack a digital clock. :)

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
Franc Zabkar wrote:

While we're rambling, I wonder how a mains frequency digital flip
clock would run on a 400Hz supply, assuming it survived the
experience. I reckon it would make an excellent bundy clock. Here in
Australia we'd cut our working days to one hour ... just enough time
for lunch. Time would fly.

- Franc Zabkar
Click to expand...
I once worked at an avionics manufacturer and one of the pieces of lab
equipment was a variable frequency AC mains generator. We took a spare
one and sneaked a hidden cord to the time clock. We called it the
"overtime generator".
 
"Steve" <emailstevecooke@yahoo.co.uk> wrote in message
news:cfa4be70-1b3c-4c4e-8cdb-739215fa08ed@d1g2000hsg.googlegroups.com...
I am building a piece of equipment for the aircraft industry that uses
a 115V 400Hz electrical supply. I have found I need to fit a cooling
fan (like a PC one but a bit wider - about 5 inches diameter) and have
got a 120V 50/60Hz one.
Will this work? Impedance wise a higher frequency would mean less
current drawn by what is presumably a mainly inductive load, but my
main query is are fan rotation speeds related to the AC supply
frequency? If so I guess trying to run a fan at about 7 times it's
rated speed would not be a good idea so I haven't yet tried it.
Click to expand...
I worked on avionics equipment for a lot of years. I retired in 1997. Back
in 1966 while in the Air Force, fresh out of Avionics school. I was sure a
115 vac 400 cycle transformers would work just fine on 60 cycles. "I was
young and knew every thing." An old Master Sargent wired up a 400~ 115 volt
transformer to 60~s. He said watch and learn. Within 15 minutes the
transformer overheated and started to smoke. I've remembered that lesson
all these years. Transformers and induction motors are frequency sensitive.
Has to do with current flowing in the core of the transformer. Some test
equipment is designed to run on both 60 and 400 cycles.

I would be very careful using 60 cycles in circuit designed for 400 cycles.
I think in most cases it will not work. If you do try to run the equipment
on 60 cycles. Be sure to not leave it unattended even for a short period of
time because when it starts overheating smoke and fire will be close behind.
 
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