wiring fans

webcrawler42 · 12-12-2005, 04:10 PM

i just got 3 120v fans for free and i'm going to mod them into a case. i realize i will have to bring in outside power, just strip a cord? i am going to wire the 3 in seiries that would make them run 1/3 speed? lastly i want to contol their speed do i just need a variable resister between the power and the 3 fans, if so do i need a special rated one? please tell me if i am correct, wrong, and some suggestions.

emice · 12-15-2005, 02:51 PM

Wiring them in series will reduce voltage but won't make them run at 1/3 speed, it will only lower the torque of the motor. Lowered torque won't slow the motor down, at least not until the torque gets so low that the internal friction of the motor slows the fan down. You might get some slow down wiring in series if the numbers just happen to work out, try it and see if you get lucky.

It works this way because AC fans are typically designed to be synchronous - they run at a speed in proportion to the AC frequency. An audio amplifier fed a sine wave below 60hz should slow it down, but this is too much expense and work.

If the 3 fans is series don't work, I would look into an electronic type ceiling fan speed controller from the hardware store, wiring the fans in parallel with it.

The page below has practical information -

http://www.fancollectors.org/info/speed.htm

webcrawler42 · 12-16-2005, 03:29 PM

thanks for the reply, life got busy so i will play with them in a week or so and tell of my fan adventures.

webcrawler42 · 12-18-2005, 10:35 PM

what wiring do i use, do i have to use 12 gauge?

12-12-2005, 04:10 PM	#1
webcrawler42 Lieutenant Junior Grade Join Date: Aug 2004 Posts: 105	wiring fans i just got 3 120v fans for free and i'm going to mod them into a case. i realize i will have to bring in outside power, just strip a cord? i am going to wire the 3 in seiries that would make them run 1/3 speed? lastly i want to contol their speed do i just need a variable resister between the power and the 3 fans, if so do i need a special rated one? please tell me if i am correct, wrong, and some suggestions. __________________ http://webcrawler42.atspace.com/

12-15-2005, 02:51 PM	#2
emice Ensign Join Date: Apr 2002 Posts: 9	Wiring them in series will reduce voltage but won't make them run at 1/3 speed, it will only lower the torque of the motor. Lowered torque won't slow the motor down, at least not until the torque gets so low that the internal friction of the motor slows the fan down. You might get some slow down wiring in series if the numbers just happen to work out, try it and see if you get lucky. It works this way because AC fans are typically designed to be synchronous - they run at a speed in proportion to the AC frequency. An audio amplifier fed a sine wave below 60hz should slow it down, but this is too much expense and work. If the 3 fans is series don't work, I would look into an electronic type ceiling fan speed controller from the hardware store, wiring the fans in parallel with it. The page below has practical information - http://www.fancollectors.org/info/speed.htm Last edited by emice : 12-15-2005 at 03:03 PM.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

12-16-2005, 03:29 PM	#3
webcrawler42 Lieutenant Junior Grade Join Date: Aug 2004 Posts: 105	thanks for the reply, life got busy so i will play with them in a week or so and tell of my fan adventures.

12-18-2005, 10:35 PM	#4
webcrawler42 Lieutenant Junior Grade Join Date: Aug 2004 Posts: 105	what wiring do i use, do i have to use 12 gauge?

User Name
Password
Remember Me?