Help needed

[Allar8]

Hello guys,
I've read your forum quite a bit but it was very hard for me to find what I was looking for, so I decided to post and ask directly to people more expert than me, sorry if my question will be stupid or if there was alredy an answer somewhere.

I'm actually no expert in electronic so forgive me in advance, but I would like to measure the current used by many of my woodworking machines (mostly monophase) which varies according to speed and usage, so I need to make actual measures to understand how they behave.
I was trying to find a solution to this problem and it came to my mind that there are multimeters, or maybe clamp ammeters, who can log data and could help me analyze the current graph on a pc later and have a clearer idea of what is going on when I do certain tasks. However I came to the conclusion that all those devices work that way only when connected to a PC, which is something that I would like to avoid, and those with internal storage are really too expensive for me.
There's no way to log the data for example on a usb pen drive or something like that?
Or maybe there is an instrument that could make such measures and let me access to a way to store the measured data?
I hope to have expressed the matter in an understandable way, I'm an italian girl so english is not my mother language

Maybe you know something that could work for this job and could me a suggestion about what to do to solve the problem.
Thank you very much to everyone and merry Christmas to all! 

[Denton.Hess]

No solution to offer at this time, as I am working on a similar type data logging problem.

Just a suggestion that you trigger a video camera on, so you can see what the tool is doing, and maybe capture the AC Clamp meter display in the frame, so you can get a real time feel for what is causing your current load.

Electric Imp modules may have a solution. I am not trying to throw you a stick to chase, but they have wireless data logging solutions.

[DimitriP]

This will do it but like mentioned above, a used laptop will be cheaper...

http://en-us.fluke.com/products/digital-multimeters/fluke-289-imsk-digital-multimeter-kit.html

[nctnico]

I'd be more interested to know why Allar8 wants to measure the current and voltage. What is the primary problem? There may be a different way to solve it.

[madires]

There are inexpensive engery/power meters:
http://www.reichelt.de/Energiemessgeraete/PEAKTECH-9035/3/index.html?ACTION=3&GROUPID=5664&ARTICLE=129698&OFFSET=16&WKID=0

[Richard Crowley]

I'd be more interested to know why Allar8 wants to measure the current and voltage. What is the primary problem? There may be a different way to solve it.

Yes, that was my reaction as well.
Certainly, if @Allar8 wants to get into electronics and the microcontroller field it would be easy enough to use an Arduino, RasPi (et.al) to log voltage/power, and even a camera attached to the RasPi to show what the tool is doing at selected intervals, etc.

But the more basic question is the motivation for wanting this information. Indeed it is quite probable there is a much simpler way of solving the problem.  Not to discourage @Allar8 from getting into the hobby.

[Richard Crowley]

You want a complete newbie to build something directly tapping into mains voltage??? With the other end plugged into USB port???

You did not identify which posting your are replying to, but I certainly did NOT suggest connecting anything to the mains power.  We have not got down to that level of detail yet.  We are still discussing motivation, general feasibility, and solution options.

[Richard Crowley]

You @ the wrong name in the Arduino resistor thread.  

Sorry, I don't have the slightest clue what that means.

[alsetalokin4017]

It sounds to me like a video camera, an inexpensive inline power meter, and a pencil and paper, followed by a spreadsheet analysis of the manually recorded data, would be the most economical and easy-to-implement solution.

Connect the inline power meter between the mains and the DUT. Use the video camera to monitor the meter. Shout out verbal statements that will record DUT setting changes on the video recording. Use the pencil and paper to transcribe the data points from the video recording into a data table, then enter the data table into the spreadsheet for graphing, etc.

This solution would require only the purchase of the proper inline power meter, since everybody has a video camera built into their cellphones, most people have computers, and the LibreOffice spreadsheet program is freeware. And it would not require any messing about with mains wiring other than simply plugging the meter inline with the DUT.

[SeanB]

Power meter off eBay is pretty cheap, should be under $15 for something reasonably usable. I just bought 4, though the hardest part is getting the EU style Schuko inline sockets to use them, I want an earthed one, so do not want to use the common garden tool sockets that are plentiful. Just must remember to buy some next week.

[PaulAm]

A clamp on current probe, meter with either rs-232 output or USB + cheap laptop.

I had to track down a current gremlin in a car once and used a Triplett DMM with serial output hooked up to a laptop using kermit to  log the data to a file.

Might be nice to get a timestamp, but that's about the minimum to log data.

Depending on the meter, it might take a command to make a reading in which case you could write a teeny program to sample the data once a second and add a timestamp.

Probably no way to do this really cheap without having to write a little code.

[cponcsak]

If you were wanting to do data logging over a long time period, I would recommend Ubiquiti's  mFi series of gear. You can get a small, 3 plug power strip for 60 bucks that will log the power consumed for each plug independently or spend $100 and get an 8 port strip. You can even just replace your outlets with them. They also come in a $15 POE clamp that goes run on the mains wire. Really amazing stuff.

http://www.amazon.com/Ubiquiti-mPower-3-port-Power-Wifi/dp/B00CXWS848/ref=sr_1_6?ie=UTF8&qid=1451157609&sr=8-6&keywords=ubiquiti+mfi

http://www.amazon.com/Ubiquiti-Networks-mFi-CS-Current-Sensor/dp/B00HXT8G1Q/ref=sr_1_7?ie=UTF8&qid=1451157634&sr=8-7&keywords=ubiquiti+mfi

https://www.ubnt.com/mfi/mpower/

[Joule Thief]

A clamp on current probe, meter with either rs-232 output or USB + cheap laptop.

on the cheap...

the current probe

https://www.google.com/search?q=prototype+pcb&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiC-ILamfrJAhVKPj4KHRD1DZYQ_AUICSgD&biw=893&bih=534&dpr=0.9#tbm=isch&q=hantecch+current+probe&imgrc=qlVuv1ey9Lpm4M%3A

and the meter with logging software

https://www.eevblog.com/forum/buysellwanted/fs-digitek-dt-4000zc-tekpower-tp4000zc-with-discount/

[Allar8]

Let's start from the beginning.
My reason to measure the power used by my woodworking machinery is the need to understand precisely how much power is needed for every machine or every job, to be able to rationalize the use of electricity, which could mean what things I can keep on together or even, more trivially, if I can use my bench saw together with a shop vacuum while the dishwasher is working. Most important, I would like to know WHAT to turn on and off to stay inside the 3kWh limit.

It seems there are different options, mostly requiring me to forget about data logging.
I guess the most sensible would be to use a multimeter or ac clamp and be content with just the maximum watt absorption, but I'm not sure it would be the best route.
Maybe I could try using something like this http://www.amazon.co.uk/dp/B015GQOLU2?psc=1 and simply place it in a place I can look at while working, but honestly I would like to avoid looking elsewhere while using a benchsaw :p Also I'm not sure about the precision of such devices.
Ubiquiti's kit seems very interesting, but I'm not sure I can find it here in Italy, I will have a better look into it.

What about a device like this? http://www.conrad.it/ce/it/product/125444/VOLTCRAFT-ENERGY-LOGGER-4000-LCD-0001-9999-kWh-4320-h
It seems to be able to also log data onto a sdhc, I think it could be a good option for my needs but in general it seems a very promising little object.
Sorry for the link in italian but I think that website can be translated in every possible language

Another idea would be to use something like the Owl or Efergy power monitor, but I'm not sure it would be accurate and handy enough, and I would like to avoid having to care about changing batteries every now and then, even if that could monitor the entire house energy consumption.

I don't know, I will still have to ponder over the whole subject.
If you have any ideas I didn't think about I will be pleased to hear it!

[Allar8]

BTW what about smart plugs?
They seem to be able to also monitor consumes, at least some of them 

[Denton.Hess]

If you were wanting to do data logging over a long time period, I would recommend Ubiquiti's  mFi series of gear. You can get a small, 3 plug power strip for 60 bucks that will log the power consumed for each plug independently or spend $100 and get an 8 port strip. You can even just replace your outlets with them. They also come in a $15 POE clamp that goes run on the mains wire. Really amazing stuff.

Nice share.
The documentation says that the current sensor can handle up to 100A RMS.

It sounds like the real issue, Allar8,  is you need basic power consumption fingerprinting, and a method to warn you if you get to 95% of 3 kWh.[/size]