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Ampere / Voltage Converting

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k0kl00n

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Anybody know how is the idea, schematic or circuit that can converting high AC ampere (~0-30A) to low DC voltage (>5V)?
 
k0kl00n said:
Anybody know how is the idea, schematic or circuit that can converting high AC ampere (~0-30A) to low DC voltage (>5V)?

A transformer is all that's needed, but you need to know the voltage of the input - the current is simply dependent on the load, you just need a big enough transformer to handle the maximum current requirement.
 
k0kl00n said:
Anybody know how is the idea, schematic or circuit that can converting high AC ampere (~0-30A) to low DC voltage (>5V)?

The most common method is to use a current transformer of 30:1 or 60:1 or 150:1 ratio and then connect a resistor of proper value to the secondary of the transformer to get some AC volts at 30A. You can then rectifier it to get a DC 5V.

If you calculate the value of the resistor correctly, then the peak rectified voltage will gives you DC 5V when AC 30A is flowing in the primary.

You do not need to break the AC circuit which is nice and safe, but just pass the cable with 0-30A through a current transformer forming a one turn coil. If you have 150 turns wound on the core as the secondary, then the transformer ratio is 150:1. With 30A flowing in the primary, the secondary current is 0.2A rms. Because the rectifier circuit gives you the peak voltage, what you need is a resistor that give 5V/1.414 = 3.54V rms at 0.2A and that works out to be around 18 ohms. The 1.414 is the convertion factor from peak to rms.
 
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