Permission to Post?

[grimjordax]

I am writing to ask if I should post details of my power monitoring system. It watches voltage and current sinewaves of household power and samples them into memory simutaneously and then performs KVA/KW, PF and other calculations which are transmitted via rf to a handheld receiver. It interfaces directly to power via CTs and voltage isolating sense resistor boards. I am only asking first because my last project was apparently deemed to dangerous and this one in my book, is much more potentially dangerous. So, the million dollar question is: Can I post it.

 

[manuka]

Phew - I'd suggest you first specify if PICAXEs are used. This forum is used as a resource by all manner of impressionable folks,myself included, & it's indeed possible that your project may be too lively for the unwary!

But why such an approach, especially in an age when plug in device monitors are so cheap. At a whole of house level no doubt you are up with the safe monitoring the utility board "winking LED"technique?

Extra: Just what was your "dangerous last project" actually about ?

 

[BeanieBots]

As stated by Manuka, first off, is it PICAXE related.
Secondly, you need to make it very clear what/where any potential hazards may be waiting to bite and as this is mains related, if there is any local legislation that might come into play.

Personally I would be extremely interested in such a project as it is something I have tried in the past and am currently undertaking so I have very selfish reasons for wanting you to post.
In particular, I do not think PICAXE can run fast enough to do proper KVA or PF measurements that will yeald better results than using assumtions about the waveform. Maybe you have employed analogue methods? I tried those but didn't use proper matched pair transistors and found that the log/anti-log circuits gave such poor results that again I resorted to making assumptions.

Assuming you have solved the PF issue, then it would be possible to use a certified wall-wart type (ie safe) method of voltage measurement, so there does not NEED to be any dangerous mains connections.

Please post your ideas.

Manuka, in the UK this is a very topical and sort after issue. The problem with the cheap commercially available units is that they do not provide a method of DOING anything useful with the information REAL-TIME.
eg control of loads such as immersion-heaters, fridge-freezers ect. based on PV, heat-pump and other energy producing/saving devices. Products which can do this do already exist but cost $$$$.

 

[JimPerry]

Phew - I'd suggest you first specify if PICAXEs are used. This forum is used as a resource by all manner of impressionable folks,myself included, & it's indeed possible that your project may be too lively for the unwary!

But why such an approach, especially in an age when plug in device monitors are so cheap. At a whole of house level no doubt you are up with the safe monitoring the utility board "winking LED"technique?

Most projects should come with a health warning (which end to hold the soldering iron?) Warnings should be enough.

DON'T TRY THIS AT HOME goes against most of what Picaxe users are doing.

A lot of projects can be replaced with off-the-shelf mass-produced items - but we still want to build them

 

[hippy]

Extra: Just what was your "dangerous last project" actually about ?

That was a PICAXE-based 'electric shock' machine. The related thread has been temporarily soft-deleted pending a review after appropriateness and safety aspects of the project were raised.

It's always going to be contentious as to what is or is not acceptable in any forum with respect to its primary and potential audiences, and regardless of what warnings there are about risks and dangers it still has to be considered that people may simply ignore, not understand nor fully appreciate those, and may do something that creates a danger to themselves or others.

 

[manuka]

Hippy: Thanks for insight!

BB: OK on the US interest & I can assure you that - even here in "green" NZ - energy meter pondering is also well established. I've put in a fair bit of zeal over the decades on this myself in fact, & certainly recognize both the consumer motivation AND likely issues involved.

A major aspect relates to smart systems not being able to anticipate factors that humans may well be able to handle. One I recall that illustrates this relates to whole of house monitoring when my teenage kids were once having a slumber party. As an older & wiser dad I just knew that they'd be up all night,c/w heaters, fridge raiding & noisy music etc, followed by energy spikes associated with extended breakfast cooking & hot water use the next day. How can you tell a smart system to (presently) anticipate the changed energy demand for such events !?

More importantly (in light of modern vehicles being prone to electronic "lock down" when something trivial fails), would it be RELIABLE & feasible to service? I've had solar water heating systems go BADLY belly up when the likes of sensors or seals don't do their stuff, and quotes to make good can mean scrapping the lot becomes more attractive that repair... Stan.

 

[BeanieBots]

Manuka, reliable? maybe not as relaible as a 'simple' system but as with any automation (eg autopilot) you should always have the ultimate cop-out clause, namely; manual override!
How can a smart system anticipate? By doing whatever is required such that it does not need to. Put simply, energy needs are whatever they need (excluding efforts at efficiency) so the system needs to cater for maximum demand. Hot water can be stored but if it gets all used up, then you need to make more. Knowing that in advance will not help. Peak electric useage can be reduced with simple tricks such as 'fridge goes off when kettle comes on' and many other such examples of devices which do not require power at specific set times. However, you don't want the fridge off all day because somebody left all the lights on so there needs a little more intelligence to override. eg allow fridge to rise by 2 degrees rather than turn it off. Ultimately, if has to be on, it has to be on.
Then there is "dynamic demand" which looks at mains frequency to determine grid loading. When the latest soap on TV has an add, all the kettles go on, the line frequency drops and anything that does not need to be on right now can go off. eg immersion, fridge or electric oven.

My interest is in "use it or lose it" PV generation.
Lots of testing to be done but here's my biggest concern.
Scenario:-
PV generating say 2kW
House using say 1kW
Spare = 1kW
Immersion element rated at 3kW

If you switch on and off at 60S intervals, you will lose 1kW for 60s then draw 2kW from the grid for 60s. (worse than no control)
So, just how quick can the utility meter work things out?
What if we burst fire over say 1s?
How about phase angle control? Even then, the INSTANT current drawn will still be over and above that available from the PV.
If the meter is PERFECT, it will register the use (even though the NET is zero).
I've heard/read that most meters will allow a certain amount of 'bouncing' before they clock up units but I've not yet tested this on my own unit. There's no way a PICAXE could keep track of phase-fire so it's back to good old anlogue techniques with the PICAXE being fed data that is averaged over several cycles.

 

[mrburnette]

I am writing to ask if I should post details of my power monitoring system. It watches voltage and current sinewaves of household power and samples them into memory simutaneously and then performs KVA/KW, PF and other calculations which are transmitted via rf to a handheld receiver. It interfaces directly to power via CTs and voltage isolating sense resistor boards. I am only asking first because my last project was apparently deemed to dangerous and this one in my book, is much more potentially dangerous. So, the million dollar question is: Can I post it.

There are, IMO, two issues here: one is that the "forum url" is generally read-only for all. However, the second issue is that attachments are only available to those that are logged-in; that is, members. This is a distinct difference in my opinion. If the code is in code-tags, then relevant and useful information is available to the general public. But the schematics and details of construction should be available only to members; therefore, such information contained only in attachments.

The fine-line above probably needs to be further widened with a member login disclaimer that is displayed at every login... a legal crafted agreement with details or a link to details should be required only once, but a sticky on all forums should be prominent to the effect that members that construct projects acknowledge that risks are involved... you know, the TV drug ads that basically say you are a potential candidate for death if you take their drug.

In my mind, not posting is a kind of censorship which is definitely within the authority of RevEd to regulate but would have potential knowledge impact on the registered community.

Ray

 

[hippy]

you know, the TV drug ads that basically say you are a potential candidate for death if you take their drug.

I imagine that contrasts different attitudes quite well. I've seen those ads on US TV and found them somewhat bizarre. In the UK we don't have those, have greater restrictions on what can be advertised and even sold directly to the public.

While cigarette advertising has gone, drinking and pharmaceuticals are tightly controlled, there's still some controversy over adverts for gambling services. There's a parallel with the debate on allowable PICAXE content - is it benign or dangerous; does it draw you down a path you might not want to have gone, or is it your choice and your responsibility to make the informed decision. Should it be allowed or banned ? Which is the greater good ? There's no single answer but someone has to draw a line.

 

[mrburnette]

<...>
There's a parallel with the debate on allowable PICAXE content - is it benign or dangerous; does it draw you down a path you might not want to have gone, or is it your choice and your responsibility to make the informed decision. Should it be allowed or banned ? Which is the greater good ? There's no single answer but someone has to draw a line.

Yep. But it would be a sad day to pull a post because a member suggested testing the power supply with a DMM and we all know that there are numerous dangers around power supplies... someone could get hurt... or worst could be killed... or worst, could sue. I don't have an answer hippy... if I was told to use a screwdriver to adjust a POT and I fell off my stool and stuck the darn thing in my eye... can I sue the forum?
IMO, drawing the line is the first step at taking human rights and restricting them for the "greater good." We saw where this all led back in WWII.

-Ray

 

[grimjordax]

My feeling is a very American one. YOU are responsible for yourself. YOU are also responsible for your children. Yes there should be warnings posted about the dangers of a project. But ultimately, just imagine if the internet was cleansed of all possible information that someone could hurt themselves with (this would be equal to book burning). I can go down to the city library and find tons of possibly dangerous information at my fingertips and the same info is available to any 10 year old. So who has to be responsible? YOU do. Teach your children who are interested in this sort of thing what not to do and about general safety practices. Supervise them. That is YOUR responsibility. If you are over 18, then educate yourself. Yes, I know all products and projects should come with safety warnings. But kindling together your own project is very different than buying a pre-built product from a store. The makers of such product ARE liable for the operation and design of their product. However, making your very own thingamajig from scratch from instructions in a magazine or the internet is very different in the eyes of the law. YOU are assuming the onus of proper operation. YOU are responsible to make sure you aren't doing anything dangerous. Even if the instructions are in error, the assumption of liability is on yourself as you have chosen to take on this mantle of creator. That being said, all precautionary statements should be made and points of possible danger should be pointed out. That is my opinion. Yours may vary.

 

[hippy]

IMO, drawing the line is the first step at taking human rights and restricting them for the "greater good." We saw where this all led back in WWII.

But if anyone wants somewhere between 'anything goes' and 'total censorship' one has to draw a line, and ironically either of the two extremes also impact on someone's claimed human rights.

 

[srnet]

Yes there should be warnings posted about the dangers of a project.

Of course.

Did you post such warnings ?

 

[techElder]

The only worry that I had with "my last project was apparently deemed to dangerous" was that the output/result of the project was specifically designed to create just below the maximum current allowed by law into the subject that touches external electrode.

It wasn't that anyone should be warned not to stick a voltmeter probe or their finger in the wrong place and needlessly be harmed.

Some warnings should be made. Like Hippy says, "... one has to draw a line...."

 

[mrburnette]

Some warnings should be made. Like Hippy says, "... one has to draw a line...."

Must I remind my friend from Texas that this forum already has restrictions on posting some posts... for example, automotive engine accessories/modification projects. I agree with such a policy. But AC power is a vital part of electronics and even wall-warts could be banned from discussion in power supplies because some cheap products are fire/electrical shock hazards.

I'm not worried about a cautious approach to project posting or response to users, but I am seriously concerned about the thin blue line turning into a big black marker. It's about being responsible but should not be about censoring. I told hippy that I do not have the answer, but I feel strongly 'nuff about the pending decisions to cancel my forum membership if RevEd decides that member grimjordax cannot post his project info in this forum.

So, Tex, if we cannot police ourselves what is the purpose of having a muted forum?

- Ray

 

[grimjordax]

No, Srnet, I did not place such warnings as I deemed my project relatively benign. However, my constituents have beaten me about the head and shoulders with all of the different ways in which the project could be abused and/or altered. I stand corrected. I have also removed the schematic of the device from my personal blog so as any links from here won't send people to the information anyway.

Thank you, sir.

 

[mrburnette]

<...>
However, my constituents have beaten me about the head and shoulders with all of the different ways in which the project could be abused and/or altered. I stand corrected. I have also removed the schematic of the device from my personal blog so as any links from here won't send people to the information anyway.

Thank you, sir.

I consider this a sad situation and regret you feel compelled to remove material. It may simply delay the inevitable however, since another post at some future time will stir this argument again. I certainly am sufficiently annoyed with RevEd for pulling the first post and I am further annoyed with their failure to quickly proceed with providing you permission to post your design in this thread.

Further: there are many more forums available in which to post and the treatment you have received here is inexcusable. I have refused openly to assist other posters in this forum on project designs which presented modifications to automobile spark timing and attachments to the OBD because the treatment of that subject to those who would ask introductory questions cannot be adequately addressed in a ping-pong fashion. However, had the individual posted a circuit created for OBD using a PICAXE, I would have felt that was free-speech provided that the post did not encourage others to follow but was information only... following the process of how one envisions a problem, approaches a solution, implements the hardware and software, and the posting of results. This, I believe is freedom of speech.

There are plenty of websites that post all manner of dangerous formula and diagrams for weapons and websites that deal with model rockets and even the construction of propellents. We are not even into the social issues of such edge activities; however, I still support the right of the poster to post knowledge if such knowledge is not overtly aimed at harming humans or other life forms. It is knowledge and is no different than publishing in a journal or in a book with the single exception that instead of a Library of Congress number the publication has a URL.

This is Rev.Ed.'s website, but the site has demeaned value if censorship is enacted. The site has essentially no value if members abandon the site. Some serious soul-searching needs to be done both by Rev.Ed. and all of the members who participated in this thread. And please, please do not allow the rules to be crafted by lawyers and shoved up our anus like some tube for an enema. For those readers that have been silent, perhaps you should take a moment and voice your opinion before someone decides for you what will and will not be acceptable.


- Ray

 

[techElder]

Ray, I thought I made it clear that my suggestion is for "drawing the line" with a WARNING NOTICE by the OP to the potential user. I wrote nothing about "censoring" anyone. Perhaps you aim a bit towards the dramatic to make your point? <GRIN>

Again, in case you missed it, my suggestion about that WARNING NOTICE by the OP was about a bare electrode that was designed to shock the user, albeit for fun. It was not about wall warts or similar.

"...If we cannot police ourselves..." I thought that was what we were having this discussion about.

I feel strongly enough about this that I'm going to keep educating myself on this great forum; as all minds tend to change over time. <GRIN>

Must I remind my friend from Texas that this forum already has restrictions on posting some posts... for example, automotive engine accessories/modification projects. I agree with such a policy. But AC power is a vital part of electronics and even wall-warts could be banned from discussion in power supplies because some cheap products are fire/electrical shock hazards.

I'm not worried about a cautious approach to project posting or response to users, but I am seriously concerned about the thin blue line turning into a big black marker. It's about being responsible but should not be about censoring. I told hippy that I do not have the answer, but I feel strongly 'nuff about the pending decisions to cancel my forum membership if RevEd decides that member grimjordax cannot post his project info in this forum.

So, Tex, if we cannot police ourselves what is the purpose of having a muted forum?

- Ray

 

[mrburnette]

Ray, I thought I made it clear that my suggestion is for "drawing the line" with a WARNING NOTICE by the OP to the potential user. I wrote nothing about "censoring" anyone. Perhaps you aim a bit towards the dramatic to make your point? <GRIN>
<...>

Heck, me dramatic? One would think a Texan would always be first in drama... and maybe followed closely by an old vocal Georgian (originally Piedmont South Carolina which explains my stubborn as a bull attitude.)

Yes, I believe that a WARNING needs to be issued somewhere in all of the text that occurs in the login screen... because such activity keeps lawyers engaged in the small stuff and keeps them from having too much free-time to think up other nasty stuff.

When Hippy says, "... one has to draw a line...." I just do not get the impression that a banner will be utilized... I get the uncomfortable feeling that posts will be pulled. If I have misrepresented Hippy, then I am regretful... but there is certainly much uncertainty - which is to say, there is much latitude - in his words.

- Ray

FOR EXAMPLE: (Source: http://ww1.microchip.com/downloads/en/appnotes/00521c.pdf
Is this acceptable??? View attachment AN521_excerpt.pdf

 

[grimjordax]

I have decided not to post the power monitor system in this forum when it is completed. My reasons for doing so are as follows: I am not using a cheap wall-wart to step down the voltage. I am using a zener protected rectified resistive network to feed the voltage signal into the picaxe. I am doing this for accuracy and to avoid phase shifting as I am sampling the waveforms and need accuracy. The same goes for my current monitoring method of using a pre-burdened split core CT that has to be placed around the current carrying conductors and has a full-load output of .333 volts. The representative voltage is fed into my precision rectifier circuit which results in a nice rectified hump at 10x (with polarity flag for each hump) to give the picaxe 3.33 Vrms or about 4.70 Vpk at full load.

I think that if I publish this here I am going to get any number of headaches from people telling me how dangerous it is and why I shouldn't be telling people how to do this sort of thing... So in the interest of saving myself from the barrage of people always wanting to protect all of the earth's inhabitants from themselves, I will only be posting projects here that don't interface with house power and generate no more than 48VDC.

Rev-Ed owns the forum and has the right to do what they want with it.

Thank you for your time.

P.S.-Mr Burnette, do you have a list of alternate picaxe forums? Or I could just google them but sometimes there are a few that might slip by using this method. Thanks.

 

[SAborn]

When you finally do post your work somewhere then please PM me a link as i would like a look.
I started a similar project some years back but never got to finished it.

 

[BeanieBots]

When you finally do post your work somewhere then please PM me a link as i would like a look.
I started a similar project some years back but never got to finished it.

Likewise, I would be very interested in your project as I too am about to start such a venture.
There are many forums where posters have CLAIMED to have made such monitors/controllers but to date, non have posted any detail (possibly for the reasons discussed here?) so yours could well be the first.

Mine will also use pre-burdened CTs but will use analogue methods to give rms DC values to the PICAXE.
I will have no voltage monitoring because I'm not interested in actual power levels, simply how much excess current is available from the PV array.

 

[SAborn]

BB, how will you read the PV DC current with a CT, wont the CT need to be on AC cable?

 

[BeanieBots]

Output from the inverter, not the PV output. The assumption (and it's a big one) is that the current waveforms are similar enough (in shape) to give a valid Current_consumer - Current_PVinverter = Current available. I did some tests feeding CT into full-wave precision rectifier, take rms and convert to DC which then fed into PICAXE which in turn used PWMout to drive moving coil meters. The meters tracked very accurately what commercial comsumer unit readers where giving so I'm quite hopeful. Early days and lots of testing to do. My biggest concern is how the domestic meter will respond to the variety of different power control methods when the load at 100% would be greater than the PV output. ie. using the grid like a massive reservoir cap!
Quite frankly I don't see PICAXE being quick enough to do 'proper' phase relationship analysis (even dsPICs strain) which is why I'm interested in grimjordax's solution which claims PF data.

 

[SAborn]

BB, have you considered using a "Current cost meter" i think they are made in the UK, a friend uses them to monitor all his solar, house, and everythink, using a picaxe to interface with CCM and the PC for logging all data.

Might be worth the option for a planB.

 

[BeanieBots]

I have several such devices. Non of them have any interface of any use. They can only download to USB. I need real-time control.
Pulled one apart and it was just the classic 'blob' on a circuit board. Certainly can't be bothered to try and decipher the signals that go to the LCD display!

 

[mrburnette]

@grimjordax:

P.S.-Mr Burnette, do you have a list of alternate picaxe forums? Or I could just google them but sometimes there are a few that might slip by using this method. Thanks.

... I will via Private Message

Update: completed