Rectified AC has both an AC and DC component. The AC component sees the transformer inductance and reflected secondary load, which may be disturbed by core saturation. The DC component sees just the primary DC resistance, which in any decent transformer will be fairly small. Hence there will be a large DC current. Half-wave rectified AC has a DC component equal to about 45% of the AC rms value (full wave is 90% - this is how choke input PSUs work). You might get away with it provided that the transformer is badly designed: too much iron, and very thin copper.
Magic blue or blue magic smoke? Maybe the grammar experts can comment on that. I guess it depends on whether it is the blueness or magicness which is most important.
Magic blue or blue magic smoke? Maybe the grammar experts can comment on that. I guess it depends on whether it is the blueness or magicness which is most important.
There really is no such thing as DC as we are not eternal.
However a transformer with a rectified sine wave will magnetize the core in one direction only until the core saturates, (All the iron is magnetized in the same direction.) Then there is no longer any transformer action. That means the only resistance to the AC line voltage is the primary winding's resistance. That will be under 10 ohms typically. 10 ohms of thin winding wire on a 220 volt pulse will make magic blue smoke!
DF96,
Bull, the only DC component that the transformer see is while there is a flat line for about 10mS.
If the core saturates it is an electromagnet, not a transformer. Magnetizing current will increase slightly and the transformer will not be quite as efficient as it will heat up a little during what you call the "DC" component.
Instead of speculating why don't you go and try it.
Bull, the only DC component that the transformer see is while there is a flat line for about 10mS.
If the core saturates it is an electromagnet, not a transformer. Magnetizing current will increase slightly and the transformer will not be quite as efficient as it will heat up a little during what you call the "DC" component.
Instead of speculating why don't you go and try it.
That was meant as humor and a bit of a lesson in the vernacular use of the words.
Magic Blue smoke means the smoke is blue and magical.
Blue magic smoke can mean the magic is blue and smoke, or can be misread as smoke and mirrors type of stage magic.
Also according to DF97's theory no transformer coupled DC to AC converter would work because you have an alternating DC (square wave) feeding it. So tomorrow when listening to your 1000 watt car amp remember that the sound that it produces is actually a figment of your imagination, it actually does not work at all. It can only work if your car battery was a proper sine wave generator.
Nico
Nico
It has to be designed to handle that current. That is why single ended transformers are so much bigger and cost more than push-pull designs.
There are also telephone transformers designed to work with DC on the signal.
All you have to do is know how much DC current is the maximum and make sure you will still have enough core material left that does not completely saturate to handle the signal.
In small transformers this is done with an air gap. As air does not magnetize the core never saturates. This is not done in power transformers as it greatly reduces the operating efficiency.
Transformer design was in the main EE curriculum in the old days, now it is a specialty course. Unfortunately I am getting to be from the old days!
Since the primary voltage change polarity , being a sine, the transformer
will not reach saturation...
No when you design an inverter transformer you use a center tapped primary. The center tap is grounded. So first you put current into one half until the core is almost fully magnetized (saturated) in one direction. Then you put current into the other half until it not only demagnetizes the entire core but takes it as far into the other direction. The you flip back to the first half until you are back at saturation the other way.
That results in a squarish wave out, but the core sees both magnetic directions.
The idea was to put a rectifier in series with the ac line to reduce the RMS to half. That way there is no sine wave and no reversal of current to keep the transformer out of saturation.
Ok , didnt caught that part on the thread , but it s really not
a good idea as well as the OP proposition.
Best would be to look at if the transformers have a 220V winding ,
wich would be logic for a japanese export model , and if there s none,
simply swapping them with 220V models..
Doing otherwise is just asking for a lot of trouble...
I am sorry to say that a centre tapped transformer has nothing to do with it, there are many single ended inverters around. See what Wahab says, he is absolutely correct. I use the term alternating DC just to confuse the issue a little.
To the transformer connected to two wires with a little less than sine wave coming into it, it does not really care, it will remain a transformer and transform the primary signal to the secondary signal, almost identical to what you put in. However, it will remove a lot of the odd harmonics contained in the half wave rectified signal as it will also act as a low pass filter.
Easiest thing under the sun is to try it. I would like to touch on the operation of magnetic amplifiers but this is totally off topic.
To the transformer connected to two wires with a little less than sine wave coming into it, it does not really care, it will remain a transformer and transform the primary signal to the secondary signal, almost identical to what you put in. However, it will remove a lot of the odd harmonics contained in the half wave rectified signal as it will also act as a low pass filter.
Easiest thing under the sun is to try it. I would like to touch on the operation of magnetic amplifiers but this is totally off topic.
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