Something to read Current

[saratec]

I am a software engineer and my knowledge of circuits comes from my one requried AC/DC course (12yrs ago) I had to take back in college. I know OHMs Law, difference between a series and paralell circuts, and/or gates and your basic physics of electricity and am able to point out a few things on a diagram (like the ground and power source)

But ask me to design something or talk about something above the scope on wiring my 36v trolling motor with 3 deep cycle 12v batteries and I am done...

With that said, I have been given a project to read the current flowing through a house hold AC circut and measure it over time. I need a device like a clamp meter that will output data to my laptop where I then can write it to a database.

Seeing I don't even know where to being, I welcome any and all throughts. I am not affraid to role up my sleeves and do the hard work, so I am not asking for the answer (but I won't stop you if you want to give it) I am just looking to be pointed in some sort of direction...

Thanks in advance!!
GML

 

[Reloadron]

Any idea how much current?

Fluke (and others) now make clamp on current meters that will data log current (as well as voltage) and they come with software so the data collected can be uploaded to a PC. Some will even give you CSV if that is what you want.

There are also a variety of current transformers and transducers out there if you choose to roll your own data logging software. Pretty much a matter of budget and where you want to go with it. Big thing is budget.

Ron

 

[saratec]

I want to measure your typical residential branch circuts, so from my limited knowledge (and my breaker panel in the garage) they are 15 - 40 amps...

Also, I did find those flukes but was not sure what else was out there which is why I decided to post. Could you expand on variety of current transformers and transducers out there ?

As far as budget goes... I don't pull the purse strings so determining budget and feasibility is part of my dilligence. I need to find all solutions and their assocaited budgets so I am looking for any and all solutions. Thanks.

 

[Reloadron]

Well given a choice I will tell you how I would go about it. I would take a somewhat commercial approach and write my own data acquisition routine.

You need some form of current transducer as a front end so may as well start there. I would start with one of these or a like unit. Units like these are very common available from dozens of sources. Maybe in a range of 0 to 20 amps or 0 to 50 amps. Range is purely a function of what current(s) you expect to see. I would look for the 0 to 10 volt output. So what you would have is 0 to 20 or 50 amps becomes 0 to 10 volts. So now you have a nice already conditioned and scaled low voltage proportional to the actual current. You are looking at about $120 USD.

That done you will need a data acquisition device. No sense on getting overly fancy. Here I would look at one of these units or if you want better accuracy than the $29 USD version then maybe one of these units. The latter unit cost more at $100 USD but affords 12 bit versus 10 bit resolution. Both units have a 0 to 10 volt input range to agree with the sensor. This makes for easy coding. Both units have recording software. I use the latter unit all the time for projects like this. Additionally DATAQ who makes them also has a pretty good SDK (Software Development Kit) so if you wish you can roll your own software.

I am not a programmer, not even close!

However, I have managed a few data acquisition routines in VB. Using the above hardware it is easy (even I can do it) to write some software (language of your choosing) to acquire the data and dump it into a data base or something as simple as an Excel spread sheet. Your call on that note.

You mention current. You could also get a voltage transducer similar to the current transducer I linked to something like this which runs about another $100 USD. That gives you a current out of 4 to 20 mA proportional to a 0 to 150 VAC input. You run that through a 500 Ohm resistor and get 2 to 10 volts = 0 to 150 VAC. The merit to adding voltage is you can plot line voltage and current as to the load(s) that come and go on the line.

Now I would be remiss (and yelled at by other forum members) if I did not suggest using a micro controller chip. You would need to program the uC and make a board for it as well as developing and designing signal conditioning if you did not use the type transducers I suggested.

There are dozens of ways to go about this depending on what you want to do. I merely have suggested how I might go about it.

Ron

 

[kiriakos-gr]

Here is a nice link, about AC/DC clamp probes, and the Agilent U1272A that does data logging, and has a nice software for it.

https://www.eevblog.com/forum/index.php?topic=660.0

 

[4pyros]

This has been done look up "Kill a watt meter"

 

[MEJY1988]

If you are looking for a permanent solution try looking at the **broken link removed**. These can be monitored on or off if needed, and come in a variety of voltage, amperage, and phase configurations. Hope this helps.

 

[dougy83]

You said you wanted a device to output data to your laptop - if the laptop is connected continually, one of the cheapest approaches is to use a current transformer connected into the laptop microphone port (with appropriate scaling resistors) and measure the waveform from the sound card. A hall-effect transducer can be used in place of the current transformer as another option.