SERIOUS electrical emergancy guys... GET IN HERE!!!

[clide]

You are hearing that hum similar to when you first turn on the fan w/ a switch because you are starting from a dead stop. The hum is the motor loading/unloading itself between Triac pulses.

that sounds an awful lot like what were trying to avoid....doesnt it?

what type of motor is in the can max fan? i would assume its not a brush type. i have no idea really.

you seem to know and awful lot about this imnotcrazy, what would work for a can max?

thanks for your input and the link


namaste

 

[clide]

so noone has any idea how to change a fan's speed???

this is sorta ridiculous!

i guess its back to variacs as the only way to control a fans speed. weak.

 

[Che]

I use one of these: http://www.qcsupply.com/qcsupply/browse/productDetailWithPicker.jsp?productId=10105

Works great!

 

[guest 77721]

I agree with I'm not crazy. Variac's don't match up with induction motors due to the low voltage / high current / overload operation, not a good way to run a motor. The need a variable frequency AC drive or speed controller to operate properly.

Variac's do match up with universal motors with brushes which are DC motors with a rectifier that converts AC to DC.

See the reason you got away with using the variac is that the load on the fan motor is reduced when it's blocked by a scrubber. You couldn't get away with using a variac on a table saw motor, it would trip as soon as you tried to cut something.

That's awesome that your GFI kicked in. Check your UL ratings. If you don't see a sticker it's probably poorly grounded.

I'm a bit rusty with motors, it's been a while since I got into some of the details. You guys are starting to play with industrial fractional horsepower motors which there are many motor designs and they all require a particular starting method and have different ways of controlling speed.

 

[clide]

so does anyone know where to get a 100$ or so solid state speed controller and i dont mean a 20$ flimsy POS.

something with buttons and shit or something thats preferably safe. jeez.

its a crazy world we live in when the solution to the solution is the problem!

 

[clide]

ok i found some things, no idea if theyll work or not, opinions wlcome!

http://www.drillspot.com/products/46989/Dart_Controls_55AC10-21_Adjustable_Speed_AC_Motor_Control

http://www.solidstatedrives.com/ind... Drives Web/desc/KB Electronics - KBVF-13.htm

http://www.davis.com/catalog/product_view.asp?sku=7010110

 

[rave420]

FYI: A spinning motor when disconnected from a load becomes a generator....

And if the capacitor connection came lose, the motor would not start. The capacitor is what creates the spinning field. With the capacitor out of the circuit, the fan motor would only oscillate back and forth not make full rotations

Lastly, if as you say that the Variac was a "cheap, made in China" model, I wouldn't rely on the UL listing (if any is marked) is a legit one. Who knows if the (more than likely cheap) insulation they used for the Variac windings can even handle the kind of current they fused that particular unit for. Think, my fan pulls 0.7A @ 115Vac. Rated 87W reduce the Voltage by half the fan still requires 87W to drive the load. Like I said the speed reduction you see is due to loss of motor torque, therefore the fan spins slower. Just by reducing the voltage causes the first increase in current, but a motor will continue to pull more current trying to regain full speed as well as a loss in motor cooling by the fan running slower. The solid-state speed controls avoid these situations by removing the high current by completely removing the voltage supply every cycle (60Hz) the fan is still spinning and this time allows the motor windings to cool inbetween cycles moreson than the Variac type control.

It even states on the sides of the fans ( I have Fantechs) that they should be used with the KB Electronics Solid State units I provided the link for.

"Many of the cheaper variable transformers available today are made in China. There's nothing wrong with them, except that they generally have a fuse fitted - in series with the mains input. When set to a low voltage (say 20V or so), the input current is only a fraction of the output current, so it's very easy to overload them, burning windings and the brush. "

"Power delivered to non-temperature-controlled soldering irons can be varied, as can anything else within the variac's ratings. This includes BRUSH motors as used in power tools, vacuum cleaners and the like. While induction motors can also be used with a Variac, THIS IS NOT RECOMMENDED - it is easy to burn out the motor (and/or the Variac) if you don't know what you are doing." http://sound.westhost.com/articles/variac.htm

I can provide engineering refs for you to back my side if you'd like

Hey, you seem knowledgable about what you're talking about, so maybe you are the right guy to answer one of my questions.

i have one of these things here hooked up to a regular bathroom ceiling fan like this

and i was just wondering what my chances of burning down the house or electrocuting myself are. As for the construction i made, it works as it should, nothing gets too hot / makes strange sounds. The thing regulates the speed without increments. Can you maybe shed some light on how safe this is and how this works?

 

[imnotcrazy]

Rave420: That's the same kind of "Speed Controller" that my fans are spec'ed for; Diac-Triac type of controller.....

You Don't need to invest in a Variable Freq. Drive for inline fans, it'd be more than overkill

 

[rave420]

so you're saying what i build there off the shelves is actually safe?

Cool ! Thanks a lot!

 

[tree d]

** People who use electrical devices for purposes that they were not intended for and that they do not understand are playing with fire.
Quite literally.
I don't understand this obsession with speed controllers. Properly sizing the fan to your application is infinitely safer and easier than 'finding a setting that works' with some cheap ass speed controller.

 

[SpendThrift]

Since variacs arent the way to go and those speedsters cause a humming noise, does anyone have any experiences with the GroZone Temp 2V Fan Speed Thermostat?

 

[stealthScrog]

whoa...forgot to update with my email from CanFan. They said to use a Variac (instead of a triac). I realize that neither are ideal but if you gotta use one, i'm just posting what the maker said.

 

[Silver Oak]

I just posted this information on another thread, but I'll include it here too...

I talked to a factory technician for Soler and Palau, the company that makes the S&P inline fans. The tech told me that Variacs are the best possible way to control fan speed of an inline or centrifugal fan.

He said that when they do long-term testing of S&P fans, they always use Variacs because it's the cleanest way to control speed, thus giving the techs a better idea of fan life since they know that the Variac is providing clean juice to the fan.

Another interesting web site to visit regarding Variacs is this site:

http://www.ietlabs.com/Variac/Variac.html

If you read the information on the above site, and if you listen to the information direct from a factory technician, Variacs are an ideal way to control speed on an inline fan.

If you do a Google search on Variacs, you can see dozens of specific references to using Variacs safely and efficiently on inline fans.

Pretty much everything stated in this thread by "Im Not Crazy" goes completely against expert opinion on the subject of Variacs.

 

[Lazyman]

OK, get some heavy gloves on, and insulated boots, cut off all power into the building, kiss your ass goodbye, just in case. Next take a sledge hammer or maul, and beat the fucking thing till it stops biting. No half ass attemps, the most committed wins.
H

LMFAO, I was picturing a dude wailing on a poor liitle electrical device with a big ol' hammer, spark spark, HIT IT AGAIN, spark, KILL IT!!! DIE BITCH!!

Yeah replace that thing dude, check out Phason VTC-1D for a VERY cool fan controller, modulates the fan speed with temps!

 

[skulquake]

Ok so which is it? a variac could prevent the hum, but shock me or burn the house down. A solid state speed controller protects the fan but I still get the hum?

Already have a speedster and it makes the fan hum when turned down and also I have a fear I'm degrading the fan motor. That hum can't be good.

 

[bp420!]

While we are on the subject of fan controllers...I have an 6in active air fan and i'm using a speedster fan controller, I'm assuming these two work together?

 

[Mister Postman]

While we are on the subject of fan controllers...I have an 6in active air fan and i'm using a speedster fan controller, I'm assuming these two work together?

I've been using the speedster, and another similar one I bought n wired up myself with no issue for almost 5 years now.. I don't get the loud hum many people report when using speed controls either for some reason...

I use the speedster on a eco-plus 6in fan, and use the homemade one on a 6in value line fan which are both similar to the active air fan you have in design..

This is the one I bought and wired myself.. Got it at Lowes a few years back.. Lutron 5a exhaust fan speed control.. bought the control, cord, and gang box for $17..