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AC/AC power supply

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Hi folks,

I have the following problem and I wonder if somebody can give me some clue.

On my electronic board I have an AC/DC converter with the following specifications.

Max. input voltage = 277 volt
Max. input current = 70-80 mA
Freq. = 60 HZ

However my input voltages vary from 120 to 600 volt.

What comes to my mind is to have a self adjuster circuit to detects the voltages below the 277 volt and let them pass through and adjust the higher voltage. For such purpose I believe that I need a step down transformer or a clamper circuit. But I have no idea if this is feasible or not!

On the other hand, I may better to have 2 voltage converters. (As I searched in the market there is no AC/DC converter in a wide range of 0-600 volt) One gives 90-290 volt and the other 300-600 volt. However, I need to have a device maybe a relay or so to detects if the voltage is below 277 or not.

In total, what do you think and in your opinion how do you guys solve such problem?

P.S. The photo attached gives you a rough idea of what I think.

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What's the output voltage of the AC/DC converter?

What sort of PSU is it? Switched mode, low frequency transformer?

If it's a switched mode power supply, it should be able to work from DC as well as AC and 277VAC has a peak voltage of 390V so it should be able to work off 390VDC.

It really isn't feasible to have a power supply with an input voltage ranging from 120V to 600V. Your best bet is to have two different models, one for 120V to 277V and another from 277V to 600V.

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One solution which come in my mind is to put a transformer with ratio 1 : 0.46 then at the secondary the voltage will vary from 55VAC to 276VAC. If your AC/DC converter can work with that low voltage - 55VAC, then no switching will be required. But if it can't, then the transformer should be made with two secondary windings and a schematic will switch the desired secondary winding.

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