Measure high current and voltage
#1
Posted 25 November 2011 - 05:26 AM
#2
Posted 25 November 2011 - 06:18 AM
#3
Posted 25 November 2011 - 06:36 AM
Reactive, do you mean *high* voltage and *high* current?
Consider that for voltages greater than around 30V (yes, thirty), the things are getting harder and dangerous.
Cheers
Probably well over 30V... it's a substation. I figured there might be a digital component I could plug into and read the values somehow?
#4
Posted 25 November 2011 - 07:48 AM
#5
Posted 25 November 2011 - 08:15 PM
For others who might be considering measuring voltages in a residential location such as 120V or 240V (still lethal) there is a good "general" model to follow.
A Netduino (or any other micro-controller) is generally designed to operate on 5V or less (3.3V in the case of a Netduino). It is not designed to survive the application of high voltages (think of it this way, if it would kill you, it will kill a Netduino).
The best approach is to keep the high voltage (or current) on a separate board from the Netduino,
There are many Digital Multi-Meters (DMMs) out there which will output their readings on a serial port. The DMMs are designed and tested to be safe and reliable for measuring voltages and currents within their design specification. You can connect such a DMM to a Netduino via the serial interface (you may or may not need a level shifter such as a MAX232 but that is another issue).
Here is a post where someone used a DMM from Radio Shack in conjunction with a computer: http://www.linuxtoys.org/dvm/dvm.html The price they paid for the DMM seems high (old post perhaps?), I know I bought one on sale (different model) for about $30.
- Daniel Minnaar likes this
#6
Posted 26 November 2011 - 01:41 AM
#7
Posted 28 November 2011 - 04:45 AM
"I'm not very clued up with electronics,"
Eeeeek!!!!
Find someone who is!!!
Measuring over 30v is non trivial
Haha! Thank you all for your concern for my safety, but I will most certainly not be creating my own circuits for something like this - I was just interested to find out what sort of 'industrial' sensors were available and how I would interface with them.
As Mario and Jonny mentioned, using serial would be perfect for my needs. I don't necessarily want to connect these directly to the Netduino board, I just want to use it to get the values of the transducers.
For the sensors that don't have serial bus interfaces, what other options do I have?
P.s: Could someone explain how the max/min milliamps work on the Netduino? I'm a little confused as to how many each pin can handle (the datasheet mentions specific pin ranges?)
#8
Posted 28 November 2011 - 06:22 AM
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