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Double Variac fan controller project (need help with wiring)

Double Variac fan controller project (need help with wiring)

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  #1  
Old 11-15-12, 06:22 PM
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Double Variac fan controller project (need help with wiring)

Hello Folks!

I'm currently building a double variac fan controller box, each variac will control one fan. The variacs are rated at 2amps each while the fan motors are 0.8amps each. One fan is for intake and the other one is for extraction.

I know the basics of electricity however I still need some help and advice with the wiring diagram. I would like to add an ON/OFF switch, power ON light indicator and fuses.

My questions are as follows:

Does the below diagram seem ok?

Would I put a fuse on each Live OUT and one on the mains Live IN?

What fuse rating would I use for the 0.8A fans? 0.8A fuse or higher?

What fuse rating would I use on the mains Live In? would I use a fuse rating of the variacs which is 2A or higher?

I have a few 12V DC power ON light indicators left over from my last project, should I get a small 220V AC to 12v DC transformer or should I just get a 220V power light indicator and keep it simple? I kind of want to use the 12v left over indicators...so they dont go to waste.

I live in Europe with 220V

The reason why Im using variac to control the speed of the fans is because I got a great deal on the two variacs and they dont make my fan motors hum and buzz like the regular fan speed controllers...and I have allot of fun building this box!

Any suggestions or recommendations are appreciated!

Thanks
 
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  #2  
Old 11-15-12, 09:10 PM
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Nice post.....nice diagram. Well done. Everything looks perfect.

I would use a single fuse on the incoming line (L). Fuse size isn't critical. I think I would use a 5 amp fuse. Variacs are great. I have a whole bunch of them and a few up to like 10 amps. (the big guys weigh a ton) I left a pic as most people will have no idea what a Variac is. There is a way to connect LED's to high voltage ac. I'll see if I can get a small list of the parts you'll need. Just a few basic parts. A whole lot better than using a transformer. Bump the thread if you don't hear from me in a day or two.


Cheers mate
 
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  #3  
Old 11-16-12, 07:52 AM
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Thanks PJmax

ok Ill add a 5A fuse on the incoming live (L).

I have 2A variacs and I thought they were huge and heavy....cant imagine what a 10A looks like lol

I also love variacs. Last few years I was using regular fan speed controllers that all either made a buzzing noise, caused the fan motor to hum or got really warm after a short time of operation.

Decided I had enough and bought my first variac. After using it for a month I decided to buy two more. They are built like tanks and Im sure they last a long time. They dont make any buzzing or humming sounds and they dont get warm even after moths of operation and I can lower my fan speed precisely without causing the fan motor to buzz. The only drawback is that they are somewhat expensive and heavy...
 
  #4  
Old 11-16-12, 08:05 AM
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In the Philippines at least back in the seventies houses has two separate power supplies. A 120 ac and a 220 ac. All wired to the same type of receptacles. Things like radios, fans and TVs were sold in a mix of the two voltages no rhyme or reason. I was visiting in a house with a 120 TV plugged into a variac plugged in to one of the 220 receptacles. The voltage wasn't that stable and so the home owner had chosen to use a variac which he turned up and down while he watched TV to keep the voltage correct and the picture stable. Been doing it so long he didn't even glance at the built in volt meter. Just watched TV with one hand on the variac like a driver steering a car subconsciously steering the voltage.
 
  #5  
Old 11-17-12, 01:12 PM
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cool story bro! Thats pretty bass ass watching TV with one hand on the remote and the other hand on the variac lol
 
  #6  
Old 11-17-12, 02:21 PM
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Bucketman,
The only problem I've had with variacs is way down at the lowest voltage. If you encounter a larger than expected load, it is across just a few turns of the coil and puff it's gone. It was only 40 years ago so no idea what I was powering, but I remember toasting two of them. After that I always moved them to mid-range before powering up.

Bud
 
  #7  
Old 11-17-12, 07:11 PM
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Hey Bud

Thanks for the info, that's good to know.

I'll probably keep them working between mid range and 20%...so I guess just start them up at around 50% and just lower them if necessary.
 
  #8  
Old 11-19-12, 03:01 PM
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So here are a few pics of the variable transformer (variac)
 
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  #9  
Old 11-19-12, 03:06 PM
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Here are some parts I will be using

The box is a Gewiss junction box 300x220x120mm
 
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  #10  
Old 11-19-12, 03:19 PM
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So here is what it looks like now, not the final version jet...just putting it together for testing
 
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  #11  
Old 11-19-12, 03:31 PM
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Test is good!

In the first pic the lower variac is at around 30% and you can see the lamp barley lighting up. In the second pic the variac is above 50% and the lamp is well lit. I dont have a voltmeter to test the output of each variac precisely, so I use this method for now... :/
 
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  #12  
Old 11-19-12, 03:43 PM
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Got the dials on...

So I have a couple of questions...the rocker switch is working for ON/OFF however it is not illuminating when its in the ON position. Its a regular 4-pin rocker switch...I have never wired one before...what did I do wrong?

Is it too crowded inside the box?

Any suggestions or comments so far?

Thanks
 
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  #13  
Old 11-19-12, 06:18 PM
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Some pretty impressive work there. Nice job Are you sure it's a lighted switch ? If so, is it a 240 volt one. Most of those two pole switches are labeled 1A, 1B, 2A, 2B. One switch is 1A-1B and the other is 2A-2B. If you had wired it backwards the light would be always on. Could be a defective switch also.
 
  #14  
Old 11-20-12, 12:46 PM
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Thanks PJmax

Im actually a complete noob...didnt even realize its not a lighted switch. I just assumed it was when I bought it at the store...heh

Could I use something like this for the power indicator light?
Waterproof 320mA 3W Power Constant Current Source LED Driver (85~265V) - Worldwide Free Shipping - DX
 
  #15  
Old 11-20-12, 01:02 PM
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What kind of motors drive your fans? Variacs vary the AC voltage but AC synchronous motors sync up with AC frequency. You probably will be able to slow the fans down but the motors may overheat "trying" to get to rated speed. Especially if they are capacitor start, governor switched.
 
  #16  
Old 11-20-12, 05:36 PM
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Hey guy

The fan motors are permanent split capacitor motors I believe...

I used one variac for a few months on a my fan and so far it worked great. Didnt notice any heating from the fan motor.
 
  #17  
Old 11-20-12, 11:14 PM
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That board is not what you are looking for bucketman. That board is for driving LED light fixtures. The indicator is like I posted in link. Jus need a way torun on 240v.

http://img.dxcdn.com/productimages/s...94_1_small.jpg
 
  #18  
Old 11-21-12, 02:16 PM
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oh I see ok. Dont have much experience with LEDs hehe
 
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