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heat sink for transfomer

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nikhil arora

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how to reduce transformer heating
how to take away heat from the transfomer as we use heatsing for transistors is this possible with transformer

My ckt needs 5.1V@200mA i have used 9Vac transformer 500mA rating on its box i cann't say how much it can deliver.
Now i am drawing only 200mA even though it is heating.
 
A tranformer operating into a proper circuit should not get hot... maybe toasty warm... but not hot. Check out your circuit for wiring errors.

AllVol
 
i have connect current meter and measured current it draws 200mA in most active state.
 
One possibility, if you have a large smoothing capacitor, there is a very large current pulse from the transformer as the capacitor is re-charged each half cycle of the mains.
Although the average current is (say) 200mA, the peak current could be 1amp, which leads to heating in the transformer.

Try reducing the value of the smoothing capacitor. But not so low that the voltage drops too low when the PSU is loaded.

JimB
 
Some things to consider:

A. Hot is a relative term and could be the same as toasty warm. With that said, it's wise to do as you are doing to check it out.

B. Is the transformer installed where room air can circulate freely? Yes, manufacturers do pack components in tightly and sometimes they consider this in their design - some don't and suffer the reliability and failure problems.

C. If the transformer core gets hot you might be able to add some kind of heat sink material to help move heat away. If the windings are heating and they are wrapped (as I'd expect) with insulating material you might see some improvement by heat sinking the core or metal frame (if one exists) but the electrical insulation on the windings also serves to slow down the transfer of heat. If the transformer is potted or otherwise enclosed in a plastic package then adding heat sinks may not be particularly helpful.
 
Hi Stevez

Check out his other posting on this problem, this same page, "transformer heating", and he describes the transformer and LM317 heatsink as getting hot to the touch. I think he has something wired wrong, probably the bridge rectifier, because I made that same mistake once, with the same results.

AllVol
 
He posts this problem with his cheap transformer all over the place.
On another website he says the transformer gets hot without anything connected to it.
1) Not enough turns.
2) A shorted pair of turns.
3) A very Cheap Transformer!.
 
AllVol - thanks. I'll do that when I get a minute. In this case, as in others, my response is broader so it provides some ideas for others with similar problems. Others seem to do the same thing by accident or design and it's helped me a great deal. The different thoughts and ideas make it a great forum.
 
i agree with steve i post same problems in different forums to get different ideas from different gurus sitting in different countries i am Novice in electronics and want to learn all things from all respects.

I am sorry if i am annoying any one

The transformer heating was due to cheap quality transformer and in my city more then 60% transformer are of bad quality. even then they sell them at normal rates not cheap.
 
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