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transformer wattage

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paulmars

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a step down transformer lets say 2:1 requires 1/2 the wattage, correct? For every watt it uses it provides 2 watts, excluding of course whats lost in the windings. I have a 220 to 110 transformer. The output says "110v", that's all. The input side says "220v "VDE" step down transformer max 300 watts". Now if the max it can safely use is 300, then the 110v side could pull 600 watts safely, right?"
 
You have the concept entirely wrong.

Watts "in" equals watts "out".


If the input voltage is 220v and output voltage is 110v and the transformer is a 300watt design, the output current will be slightly less than 3 amps and the input current will be about 1.5 amp (due to the losses in the transformer).

In other words the transformer in your case, is capable of doubling the output current because the output voltage is half the input voltage. The only "constant" (or connection) between the input and output is wattage. These must be EQUAL (forgetting the losses).
 
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Generally, transformers are rated as so many 'volt-amps'. This VA rating is the product of the volts and the rated or allowed amps. The VA specification for the input or source side of the transformer, must be identically equal to the V*A product or the load, or output side of the transformer. For larger transformers, the rating would be KVA, or kilo-volt-amps.
 
Watts is energy which is volts x amps. Energy can not be created or destroyed (unless you go nuclear and that's converting mass to energy). If you had more watts out than in, that would be some form of perpetual motion, which is not possible.
 
one more thing. I plan to use this to convert 110 to 220, which is the apposite of what it was made for. Do you see any problems? Its sold as a step down.
 
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