Calculate wire size

Other Hardware General Electronics
1

Hi...

Could I use Arduino to calculate wire size based on the resistance?

It's based on the Pouillets law, I'd like to know if I could calculate the size (length) using Arduino.

I'm a beginner on Arduino, I appreciate any assistance on it.

Thanks,
Pedro

2

Your topic was MOVED to its current forum category which is more appropriate than the original as it is not an Introductory Tutorial

3

What are doing ?

Unlikely.

A short wire, example 24AWG, only has a resistance of .025 Ω per foot.

Two different gauges of wire resistances can have the same R for different wire lengths.

Measure the diameter.

4

Thanks LarryD for your quick response.

Let me explain better the project. Two parallel and flexible alambre wires (same gauges) are connected to an electrical source. An external event makes they can be touched at a point. I'd like to know the distance from the electrical source to the contact point.

I used this method years ago when I was working in a telephone company. We identify the telephone pair cable fail location by measuring the impedance. E.g. If the telephone pair cable has, regularly, 5 km but a fail is 2 km from the electrical source then the impedance is different. So, if I know the impedance then I calculate the distance of the fail.

Ok, my current project follows the same principles but has a different goal.

The max length will be less than 2 m, and it will have many parallel alambre wires.

Could I use Arduino to identify the location where two parallel wire has been joined?

Please, I apologize for my English... I know that the parallel concept means that never will be joined. :slight_smile:

5

Can time Domain Reflectometry be used in this case?

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6

Hi EmilyJane, that would be perfect but it increases the project cost.

Once the alambre wire is joined and the location is calculated then the whole system would be wasted. For that reason, I'm thinking of cheaper solutions. As I've mentioned in my first comment, I'm a beginner with Arduino, I need to understand first if one of the cheaper components of the Arduino family could be used for this.

First of all, I'd like to asses the proof of concept of my project. Second, I'll write the whole project requirement and build the first prototype.

Thanks,
Pedro

7

What is the wire material? if it is stainless steel, for example, the resistance is much higher than copper and might actually lend itself to measurement by an Arduino.

8

Without knowing the gauge of wire I'll make some general comments:

  1. The wires have to be at the same temperature. Copper changes a 0.39 %/°C
  2. The wires cannot change temperature from when not shorted to shorted.
  3. You will need an amplifier (likely differential amp) to increase the difference in resistance to a level the Arduino A/D can measure. MAYBE an HX711 might work, you will have to look at the numbers.

Without going through the numbers I don't think it's doable. The issue is mostly 2) above.

9

I've not decided on any material yet. This is a product that I want to create from scratch to provide a solution to my company.

So, first I want to understand if my concept can be implemented in the "real world". It means beyond my theory.

All elements and parts will be chosen based on cost and features.

Thanks for your interest in it.

10

Thank JohnRob... The HX711 is a very interesting component; I'll continue learning about it.

Yes, I considered the temperature changes. I don't think it will be drastically modified. I'll asses the solutions once I put all the pieces (ideas and concepts) together and I analyze them holistically.

Thanks again for your advice.

11

How can you know the resistance of the joining between the wires?

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12

Nichrome wire?

13

Your description means the normal connection and the accidental connection are a parallel connection. Therefore, you have to already know the resistance of the normal connection in order to subtract that from the new accidental connection. Do you know this resistance at the time of the accidental connection. The answer must be NO!

14

TDR is simple and it works. Subtract from the purchase price the cost of all the personnel time and effort it would take to make your idea work.

15

Exactly. The way I read it, it's a one time calibration. Rent a TDR for a da or two and you're done.

16

There are low-resistance Ohmmeters but low resistance is difficult to measure. The probe contacts and/or connector contacts and the probe leads add to the total resistance.

I've got an old meter at work that does 4-wire resistance measurements. It's got 0.001 ohm resolution but the accuracy is a little better than 0.1 Ohm.

17

I find it's more accurate, when using a multimeter, to measure the voltage drop across a <1 Ohm resistor. Many multimeters have a mV scale that has better resolution/accuracy than their low Ohm scale. Put a relatively large, known value, resistor in series and use a little mathemagic.

18

I may have misunderstood but I believe the OP mentioned the max distance is 2m.
I googled a "typical" TDR; the specification did not mention a minimum distance but it stated the resolution is 0.3m. Doesn't seem to be a useful instrument for this purpose.

19

Maybe not. I'm not familiar with all the versions.

20

Neither am I, however we evaluated a type of TDR to measure the fuel level in an automotive tank. Was too costly but was very interesting.

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