Non Contact Voltage Measurement E.g. Fluke T6 - Page 1
Forum section: electronics / testgear

author: mheruian
author_rank: Contributor
timestamp: May 25, 2018, 12:38:23 am
content: Hi Folks,Total Newbie here, not too geek to understand deep electronics, been researching for ages about measuring voltage safely and ended up seeing non-contact voltage sensor (they call them chicken sticks) so cheap but so far I only see them as detector of AC voltage and unable to measure AC voltage - why is that?Then i tried to search a cheap module sensor (e.g. like those ultrasonic sensors for arduino/uC) but I can't find any. Then I ended up just searching how chicken sticks work (e.g. capacitive voltage divider, cvt, etc.) and would like to try them as last resort because that'll be trial and error for me.Then I foundFluke T6tester that works perfectly for what I expect to see. Can I ask if there is already a same diy tester same as this fluke tester, because I've searching for a lot of days with this but I can't (I know fluke testers are too accurate and hi-end top of the line tester, but as a new electronic hobbyist, I want my small projects something to be at least on a grade level?

author: joeqsmith
author_rank: Super Contributor
timestamp: May 25, 2018, 01:19:07 am
content: There are a few threads for the T6 if you use the search. I've been trying different things with it and like the concept. I thought about trying to role my own design to improve on it. There are several patents and I would suggest you start there with your research. If you are looking for some simple circuit to pull this off for $10 in parts, I don't think you will find it.

author: SG-1
author_rank: Regular Contributor
timestamp: May 25, 2018, 01:58:38 am
content: The Fluke T6 is the first of this kind. The non-contact accuracy is 6%. Gets better when you use one probe for reference, ground.

author: mheruian
author_rank: Contributor
timestamp: May 25, 2018, 02:24:14 am
content: Quote from: joeqsmith on May 25, 2018, 01:19:07 amYeah, after looking at those threads - I, as someone new, got mind blown about why Fluke has wrong design on T6 as said by others. Never thought it is first of its kind, I thought non contact voltage sensor is already been market for a long time since chicken sticks exist already to detect if there is voltage or none and putting some amplification and calibration sort of circuit would make chicken sticks measure voltageQuote from: SG-1 on May 25, 2018, 01:58:38 amSo i guess I can't make oneneed to be bad ass smart to beat fluke out of this technology

author: IanB
author_rank: Super Contributor
timestamp: May 25, 2018, 02:46:10 am
content: Quote from: mheruian on May 25, 2018, 02:24:14 amFluke doesn't have a wrong design on the T6. They have what might be called "BATNEEC" (Best Available Technology Not Entailing Excessive Costs"). In other words, if you tried to design something better at the same level of practicality and manufacturing cost, you would be unable.The fact that it works as well as it does is amazing. The fact that it doesn't work better is a limitation of physics. What you have to decide is, is this technology worthwhile and useful to you? Can it solve a problem you can't solve more easily another way?

author: mheruian
author_rank: Contributor
timestamp: May 25, 2018, 03:43:48 am
content: Quote from: IanB on May 25, 2018, 02:46:10 amYup, actually, I'm not really sure if it was wrong design because as I said on my prev reply "as said by others". Just like you, I'm not an EE so i don't know either why I'm herebut anyway, been dreaming to be a successful hobbyist and I have this project where I want to measure voltage non-invasive same as how CTs measure current non-invasive that's why I end up looking at capacitive voltage sensor to the Fluke Y6

author: joeqsmith
author_rank: Super Contributor
timestamp: May 25, 2018, 05:34:39 pm
content: Quote from: IanB on May 25, 2018, 02:46:10 amI too am amazed with how well it works. I am also disappointed at the same time. What physics do you feel are involved that prevent it from working better? I've spent some time looking at it and believe it could be improved but maybe not. I think I just need to start trying some ideas.

author: IanB
author_rank: Super Contributor
timestamp: May 25, 2018, 06:21:32 pm
content: Quote from: joeqsmith on May 25, 2018, 05:34:39 pmOn the one hand it seems like there are too many variables to account for: the position and orientation of the wire in the measurement slot, the quality of the ground path, the effect of the frequency spectrum on the voltage ratios in the divider path, how to tune filters for wanted vs unwanted frequencies, and so on.On another hand, I feel that if this was a good, practical approach it wouldn't have taken so long for someone to attempt to make a product out of it. Typically engineers will have an idea that "this is too hard and too complicated, let's not go there".

author: joeqsmith
author_rank: Super Contributor
timestamp: May 25, 2018, 11:11:39 pm
content: Quote from: IanB on May 25, 2018, 06:21:32 pmIt's possible someone had made a similar product. It's possible we just never knew about it. There are certainly patents which I suspect show prior art.I don't think the wire position compensation poses much of a problem, nor the ground path. Talking out my ass so don't hold me to it. It's that last part of this sentence that concerns me.I won't disagree that this may be hard to pull off and that there may be engineers who would have no desire to go there. I just don't fall into that category. The whole reason I bought the T6 was because I found the concept interesting.

author: mheruian
author_rank: Contributor
timestamp: August 19, 2018, 07:21:19 am
content: I'm going to study this one and inform you on my progressseems interesting as my first project lol. Thanks for all the reply, really appreciated them all.

author: threephase
author_rank: Regular Contributor
timestamp: August 19, 2018, 10:13:12 am
content: Quote from: mheruian on May 25, 2018, 03:43:48 amInteresting, I have never heard of the acronym "BANTEEC" before. I do understand what you are getting at, but I am also wondering if the T6 concept was also a limiting factor in the design and it is possible to improve the accuracy just not in the T6 package.I would say that the T6 is aimed at domestic, commercial and industrial electricians and in that respect accuracy isn't the highest priority. If I am fault finding and I read 110V, 115V or 120V, I don't really care, I know the voltage is there, so I move onto the next aspect of the circuit. What is important to me is ergonomics of the instrument and ease of use. Fluke already had the T5 which was popular, so making the T6 fit into the T5 case may have been their priority and sacrificed other aspects such as accuracy in lieu of that.The time when I am really after some accuracy is power monitoring / analysis. At the moment voltage connections for these instruments are direct, but this has issues both with making the connections and leaving the instrument unattended whilst logging the data.A contactless voltage pickup for this aspect would be great for me, it improves ease of connection and makes things safer, whether or not it is in the same head as the current clamp or a different sensor probably doesn't really matter. Not having the physical constraints of the T6 case, may mean the accuracy issues can be addressed.Hioki are also going down the route of contactless voltage measurement, all be it at low levels at the moment.https://www.hioki.com/en/products/detail/?product_key=6409http://hiokiusa.com/wp-content/uploads/pdf/33589-A_TA_SP0001E01.pdfThe only thing after that is to make it wireless and self powered from the current in the circuit under test, but I can hold off until the following weekend for thatKind regards

author: mheruian
author_rank: Contributor
timestamp: August 19, 2018, 01:22:26 pm
content: Hi Mr.threephasethat's good info, thanks. Might as well meet those ideas if I could make it hehe