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Topic: Arduino Current Measurement_Which is best? (Read 817 times) previous topic - next topic


Feb 24, 2017, 11:33 am Last Edit: Feb 24, 2017, 11:40 am by willerpw
Hi there,

So here's the story..... I'm in the process of building a Automatic generator controller. For this to work correctly I need to supply the Arduino with as correct a possible Voltage and Current value.

Voltage input is sorted and I'm fairly happy with its accuracy, using a 240-6V transformer, then rectifying to a suitable DC range.

Now the part where I'm not sure what is the best option.

I'm using a 100A-50mA Current Clamp. Since the analog inputs on the Arduino works by supplying a 0-5VDC input, I have to convert the 50mA output from the Current clamp to a 0-5VDC measurable value.

I've browsed the internet and all I could find was attached circuit "Capture".

Why can't I use a the a 130Ohm resistor in parallel with the sensor, This will cause a 6.522V potential to be created which I would then Rectify and Filter to give my Arduino a 5V input at 100A primary on the clamp?

I have attached a test circuit diagram "Circuit 2" which I ran on LT Spice.. Has anyone used a current clamp as such yet? and how was the accuracy?

Thanks for reading


LT Spice Circuit attached


Of course you can use a resistor to convert the current into a voltage. But have a look at the data sheet, a current clamp may require a certain load for correct values. Also consider that 5V for 100A will result in only 5mV for 100mA. And consider that a rectifier outputs the peak voltage, which is about 1.4 times the effective AC voltage.

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