Alright, so let's say one plugs in a heating mantle, with the variac, and seconds later it begins smoking, the netting turns an awful brown color
(which leaves a residue on the flask), and so you unplug it. You look under the netting and there are rings of burn marks on the cotton underneath.
What could one discern from this experiment?
Bad variac?
Wrong voltage (115/220) ?
The mantle was obtained in Canada, has a SUNBIM variac, it has a metal wall around the outside, and is stuffed with cotton on the inside. The mantle
has two power cords (one for upper/ one for lower) plugged into the variac and the variac is plugged into a 115 V outlet.
So why's it smoking?Magpie - 29-6-2006 at 14:19
What is the voltage rating of the mantle? If you did not exceed this rating then the mantle should function normally without burning.
Sometimes the variac maximum output voltage is higher than the rated input voltage. For example I have seen variacs with a maximum output of 140VAC
with input voltage of 120VAC.
I normally run my mantles from 50% to 90% on the variac and have had no problems. I have 120VAC on the input and max output is about 130VAC.The_Davster - 29-6-2006 at 14:36
Did you get it new? I got a used one, and the first time I plugged it in it stunk something horrible and smoked, I believe it was from an old
chemical spill on it.Flip - 29-6-2006 at 14:46
Yeah, I got it used. It looked to be in good condition though. It doesn't say anything about the make, model, or voltage rating. I figured that if
it's a 220 V appliance, it still wouldn't fry because I have 115 V outlets. It did stink and smoke like you described, but it also browned the inside
and burned the cotton underneath the "netting." Near as I can figure, it's the controller, but the guy who sold me the mantle sold me the controller
as part of the package.
Weird.Magpie - 29-6-2006 at 14:51
Like Rogue I got my mantles used (eBay). They were from liquidation of a petroleum technical service. I too had to burn off all the oil that had
been spilled on them. I slowly heated them up to red hot until they quit smoking. They are now a clean white and look brand new! Flip - 29-6-2006 at 22:41
Heating experiment #2
Ok, so I plugged the thing back in, and set the controller to "on" but the power was right at 0 on the 0-100 scale. It took about 2 1/2 minutes for
the thing to become visibly red hot and to fill my room with smoke... the mantle is an even darker color, the cotton material underneath seems even
more burned. This thing just isn't doing as it should. Maybe I should try a different variac/ controller.Nicodem - 30-6-2006 at 11:56
Obviously your variac does not work if it sends trough the full current when at 0.Chemist514 - 30-6-2006 at 12:47
I feel for you. ouch.
Yeah... probably should do what the electronics/ham radio types do in these cases, ie, start at zero and check with a multimeter, always test surplus
gear ALOT before puting it into use. These sorts of remarks are of no use though so...
Did you burn out the heating element in the mantle? i would think not if you still get smoke from it so maybe replace whatever fabric is on the
outside and its asbestos insert material and buy a new variac or send that one in for repairs.
( i suspect any place that services electric motors could fix up the windings in the variac?)
The best of luck to you sir.Flip - 30-6-2006 at 16:10
Yeah, so I tested the current on this thing... apparently there is no variance in current regardless of the setting. It only seems to have two modes
(on/off), so it will heat at zero at full power, then turn off for awhile (unless the dial on the controller is turned up).
In any case, this is not the type of controller that we need, so i'm going to be in the market for a new one.
Arrrgh.unionised - 1-7-2006 at 05:18
Provided that you don't mind blotting out a.m. radio for a few yards you can probably get away with using a lamp dimmer. A whole lot cheaper tha
gtting a variac or a"proper" controller.Chemist514 - 1-7-2006 at 06:25
Quote:
Originally posted by unionised
Provided that you don't mind blotting out a.m. radio for a few yards you can probably get away with using a lamp dimmer. A whole lot cheaper tha
gtting a variac or a"proper" controller.
Hmmnn.... I'll take this moment to point out that if ever there was a good time to burn out a dimmer or melt insulation off of wire, this is it.
heaters and motors use alot of current, if you go this route watch voltage/CURRENT ratings VERY close.
All the best.
