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Transformer

Abhinandan

Apr 24, 2015
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upto how much temperature does a transformer(220-12V) gets heated up on continuous working....???
 

Anon_LG

Jun 24, 2014
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Have you checked the datasheet for your transformer? Do you have temperature measuring equipment?
 

ramussons

Jun 10, 2014
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It would depend on the transformer rating and its loading. By a rule of thumb (literally :D) - if it's too hot to touch, it's bad; warm is acceptable. And my thumb and your thumb can have its own definition of "hot".
 

BGB

Nov 30, 2014
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It would depend on the transformer rating and its loading. By a rule of thumb (literally :D) - if it's too hot to touch, it's bad; warm is acceptable. And my thumb and your thumb can have its own definition of "hot".

even this may depend some on how hot the transformer is designed to run under continuous and peak loads.

for example, it may be running hot enough to burn and blister ones' skin if they touch it, but still running under their rated continuous load (*).

it may also depend on things like what company made it, what application it is intended for, and if they are based in the US or China, ...


*: the thing may come encased in a coating of black epoxy, and trying to run it anywhere near its rated power makes it run hot enough to boil water...
 

Colin Mitchell

Aug 31, 2014
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Any transformer you cannot hold will start to smell and its life will be very short.
 

Myhay

May 18, 2015
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Usually a transformer heats up to let's say 15-20 degrees. I find this value acceptable as most of electronic components are rated to work a number of hours at 25 degrees.
A transformer will heat up more that it should when the current needed by a consumer reaches to maximum that can be provided.
If you have 220-12V, 12W ( this meaning 1A) if you connect to it a light bulb of 6W that means about 0.5A. The transformer should not get hot at all ( at least not more that 15-20degrees).
If you change the light bulb with a bigger one - 8W, 10W the transformer will get hotter.

If you power up a light bulb rated at 15W it will work for a limited period of time because it will exceed the maximum current of transformer and it will get too hot and it will get defective.

Bear in mind that if we are talking about consumers with variable load the situation will be a bit worse for that transformer.

Hope this helps.
 

BGB

Nov 30, 2014
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Any transformer you cannot hold will start to smell and its life will be very short.

apparently, this is part of why they make them foil-wound and coat them in epoxy. doing things this way, they can apparently push the operating temperature up considerably without the transformer frying itself (there is no enamel coating to worry about, as a separator is used, nor the issue of the copper or aluminum windings or iron core reacting to the air).

however, yeah, if it is wound with magnet wire or similar, and this is left exposed to open air, then yes, prolonged operation at 100C or similar would be bad.
 
Last edited:

signalman72

Jan 26, 2014
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It seems I remember that laminated core transformers have better thermal stability than solid core because lamination reduces the eddy effect. I could be wrong though.
 

BGB

Nov 30, 2014
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It seems I remember that laminated core transformers have better thermal stability than solid core because lamination reduces the eddy effect. I could be wrong though.

pretty much. you don't really want eddy currents, so laminated steel is used.

too many eddy currents will cause the steel to try to turn into a magnet (strongly opposing the change of field direction, and generating considerable amounts of waste heat as the field flips back and forth).

the way the layers are cut, how thick they are, ... effect how the magnetic fields interact with the metal (influencing where they go, and how strong the eddy effects are and in which direction). so, they can help direct the field to where it is useful in the transformer, and eliminate currents in directions which are detrimental to performance.


it is also possible to use ferrite instead of steel or iron, which basically entirely eliminates the eddy effect (and alters its magnetic properties).

the use of ferrite results in relatively little inductance, allowing the direction of a field to reverse rapidly (such as for a high-speed transformer or electromagnet), though results in worse performance at lower frequencies (so, laminated cores remain preferable for things like power transformers).

I am not as sure about motors. apparently ferrite is used in some small high-speed motors. looking into it, apparently it is not as powerful or efficient as laminated steel when used for larger motors.

I am left wondering about the prospects of a motor made with iron-containing 3D printing filament (they basically mix powdered iron in with PLA or ABS plastic for the printer filament), or how this would compare with a person making their own by ordering a large jar or iron oxide dust (to mix in with the PLA or ABS). (the iron-containing filament is pretty expensive at around $15/lb).
 
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