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Topic: DC Current Sensor (Read 4 times) previous topic - next topic

Justin Berken

Jan 26, 2010, 04:47 am Last Edit: Jan 26, 2010, 05:04 am by berk0080 Reason: 1
Hello, I would like to use an arduino to monitor and log the current being produced by a small solar panal array.  I have seen people use hall sensors but am wondering what kind to purchase for DC current sensing. Is there a more appropriate way of interfacing a DC current sensor with the arduino?

These are the sensors I have come accross so far.

http://www.jameco.com/Jameco/Products/ProdDS/627591.pdf
http://www.jameco.com/Jameco/Products/ProdDS/627621.pdf


Thanks!!!!

pwillard



ZXCT1009 is a 3 pin current chip I use in power supplies to monitor load current.  It senses the drop across a low value load resistor. It might work.

Justin Berken

I came across a thread where someone simply measures the voltage across a resistor and calculates the current based on V=IR. This should work right?

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1205745528

Thanks!!!!

Grumpy_Mike

Quote
This should work right?

Only if you monitor the current in the return path, that is the ground side. If you use the top side and the voltage is above 5V then you need a current sensing resistor (low value), then either side of that you need a potential divider to bring the voltage down to under 5V, then you need to measure the voltage on both sides of the resistor and the result will be the difference between the two.

Kamala

Have a look at www.devicecraft.com. Very good prices and he posts worldwide cheaply too. I've ordered some and waiting for them to arrive. I will probably pot them in epoxy when thery are set up and working.

jackrae

You can get hall effect sensors that are capable of measuring DC current and they are not overly expensive.  They generally give a DC voltage or current output.  Some give 0-5volts for the current range selected so are perfect for direct connection to the Arduino. If you conduct a search within this area of the forum you will find topics related.

I would avoid the use of a resistor measurement technique since you are tapping onto potentially high DC and if you get the reference connections wrong you'll be buying a new Arduino (as a minimum).  Grumpy Mike referred to the requirement by stating the connection had to be on the ground side but didn't emphasis why this should be so.

The hall device also gives electrical isolation from your PV voltage (including possible lightning strikes).

Jack

Graynomad

There are also high-side measuring chips such as

AD8210/2/3
INA138/139/169...
MAX4080/1

etc.

All these are designed to handle high voltage on the sense resistor but work on 5v logic.

______
Rob

Rob Gray aka the GRAYnomad www.robgray.com

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