ABC Inventors - electrical safety device

"Ross Herbert"

** It makes them even more mysterious.

** That bit worries me a LOT. ** The device is alleged to sense voltage on conductive surfaces that are NOT part of the AC circuitry - but is this in fact the exposed metalwork or not ??? AFAIK the inventor has never made this point clear.

I suggested earlier that internal, non live metalwork ( or maybe some deliberately added metalwork) could be used to sense if the appliance has become wet.

I now suggest that this is the ONLY way the Protex could be designed and NOT break the rules governing Class 2 - since one cannot connect anything to exposed metalwork other than a Y2 capacitor of low value ( 10 nF).

Until the inventor has a prototype device, installed in an appliance, approved by a registered approvals testing lab he has nothing more than a cute idea that cannot be sold to anyone.

.......... Phil

It concerned me a little as well.

Yes you did, and I was agreeing with you.

Exactly.

At the moment, I can't see the manufacturers of conventional RCD's or Line Isolation Overload Monitor equipment (or simply, LIM), as used in hospital theatre ac supplies, will be quaking in their boots at the prospect of Protex making their systems obsolete.

"Ross Herbert"

** Red herrings and irrelevant straw men are indeed your speciality.

........... Phil

Phil,

I note that you conveniently snipped all of your own text to which I was responding so that the relevance of your accusation against me is missing. I believe you have vilified others in this forum who have done the same when responding to your posts.

I think you misunderstand the difference between a "strawman argument" and a simple statement which "expresses an opinion".

FYI, a strawman argument is a statement a person makes if they want to attack an opposing position.

I simply made a statement (that part fits the definition at least) expressing my opinion that I do not foresee Protex superseding existing approved equipment designed to reduce shock hazard from ac mains supplies anywhere in the near future.

Can you tell me, with regard to Protex, exactly how my statement of opinion is making any argument at all? Furthermore, how was my statement in any way attacking your "position", which BTW, I am not "opposed" to?

I thought I was essentially in agreement with your assessment of Protex, and not in opposition to that assessment.

"Ross Herbert" "Phil Allison"

** That straw man of yours stands alone and in isolation to any other words. ** IMO - a "straw man" is an irrelevance put up merely because the author knows it is easy to knock down and that readers will do that without any additional persuasion.

It usually has some vague, allegorical connection to the issue - as yours did.

But ultimately its effect is to muddy the water.

** It was a pure "straw man" - ie nothing to do with the original issue.

Lots of folk who post on NGs **love* to use them to confound discussions, big note themselves and send the debate off in a new direction they have chosen and want it to go.

I just get tired of seeing so many of them.

........... Phil

Let's get things straight. By accusing me of setting up a "straw man" you are in fact falsely attributing my expressed opinion as making an argument (or stating a position) purporting to be factual. You did this in order to get me to respond so that you could attack me. I think that you have added a new technique to the list of definitions of what constitures a "straw man".

1. Present a misrepresentation of the opponent's position, refute it, and pretend that the opponent's actual position has been refuted.

You have modified the technique in point 3 by adding an intermediate step as follows;

What you did by accusing me of setting up a straw man was to misrepresent my position in what was nothing more than an expressed opinion, thus provoking a response which then allowed you to attack my opinion and refute it as if I had presented it as a factual argument in the first place.

If ever anyone was guilty of setting up a "straw man" this surely proves it is you who is the transgressor. It is clear from your responses below which shows this to be the case.

An expressed opinion is simply one person's belief of what may occur. You can either agree or disagree with an expressed opinion but you have attributed that opinion as being a factual argument. It is clear that you have falsely attributed my expressed opinion as a factual argument because you now refute it as "vague" and making only an "allegorical connection" with the subject under discussion.

Your new technique essentially conforms with that in point 3 of the list of techniques.

Again, this response shows that you have falsely attributed my expressed opinion as putting my position as a factual argument when it did nothing of the sort. My expressed opinion was clearly associated with the original issue.

You are now resorting to accusation by inference. By associating this particular discussion between you and myself, with the generalisation "lots of folk" etc. etc., you are including me in that nebulous group, "lots of folk". Having now established the fact that I am included in that group you then proceed to denigrate them. You then issue the coup de gras by portraying your case as factual by stating "I just get tired of seeing so many of them."

Boy, are you a sneaky buggeer or what?

For those who don't want to follow the link above;

Definition of Straw Man:

The straw-man rhetorical technique is a the practice of refuting weaker arguments than one's opponents actually offer. To "set up a straw man" or "set up a straw-man argument" is to create a position that is easy to refute, then attribute that position to your opponent.

One can set up a straw man in several different ways:

1. Present only a portion of the opponent's arguments (often a weak one), refute it, and pretend that all of their arguments have been refuted.

2. Present the opponent's argument in weakened form, refute it, and pretend that the original has been refuted.

1. Present a misrepresentation of the opponent's position, refute it, and pretend that the opponent's actual position has been refuted.

1. Present someone who defends a position poorly as the defender, refute their arguments, and pretend that every argument for that position has been refuted.

2. Invent a fictitious persona with actions or beliefs that are criticised, and pretend that that person represents a group that the speaker is critical of.

Some logic textbooks define the straw-man fallacy only as a misrepresented argument. It is now common, however, to use the term to refer to all of these tactics. The straw-man technique is also used as a form of media manipulation.

Why my expressed opinion cannot possibly be interpreted as a straw man when referred to above 5 definitions:

** You made no argument in any part of your response to my original post and I did not attribute any claim as being your own so there was nothing for me to refute.

** I did not misrepresent anything you wrote in response to my original post. In fact I agreed with your position.

** I did not present anyone or invent a fictitious persona whose beliefs I was planning to criticise.

** My expressed opinion does not even fit the more liberal description of being a "misrepresented argument" because there was no argument in it at all. Also, my expressed opinion could hardly have been interpreted as being an attempt at "media manipulation" either, so when all is said and done Phil, you just like to make wild accusations whenever it suits you.

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Hi Ross,

Do what just about everyone else does here - ignore him - read his stupid dribblings if you have to but never respond - he is a vile creature! The sooner he leaves this group the better and then it will get to where it should be with kind considerate people like yourself helping others. This is one of the worst NG's around thanks to the likes of him - just look at some of his recent posts.

He chastises someone in "Which is better electric or blade" cause they should note that as OT yet he posts "Poxy is Homophobic" without the "OT". What has homophobic got to do with electronics?? The guy is a complete mental wasteland.

Forget it - move on - spend the time going for a walk in the park.

Cheers.

Hi Chris,

Believe me, I tried hard not to get involved with Phil on this one. In the distant past Phil engaged in some vilification of me in his posts and we both came to an agreement that we would not respond to each other's posts. That has lasted at least 12 months I think.

If you check the thread you will see that I responded to the OP and then Phil broke our agreement and responded directly to mine and since he was sounding reasonable I replied. It was all a ruse to suck me in so that he could get stuck in to me once more. I think he is finding it difficult to get a good rational argument lately and he has to resort to vilification, denigration and bad mouthing people much sooner than he normally does, while at the same time trying to turn the blame and excuse his own bad behaviour. I must admit that so far he hasn't actually started in with the foul mouthing as yet, so here's hoping....

I promise I won't respond any further to Phil's provocation.

Cheers.

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"OT".

Good on You!

Cheers.

"Ross Herbert"

( snip an enormous pile a paranoid crapola)

** Kindly go and get stuffed.

Do not pass go - do visit a psychiatrist on the way.

.......... Phil

about

The Australian Patent application abstract can be found here:

and the full patent can be downloaded here for a small fee:

I have a copy already downloaded if anyone is interested.

Dave :)

Also, for the full patent try here:

Dave :)

"David L. Jones"

** Oh dear.

Beware of electricians from Newcastle.

........... Phil

You gotta love patents. He could have kept all the secrets to himself and potted the whole thing, and no one would know how it works. Now, many $$$$$ later, it's all there for the world to see.

Dave :)

** It is only a patent application far as I can see.

That idea does not seem nearly novel enough to deserve a patent.

** Madness - the only way any such device ( IF it worked and was and legal to install ) could be commercially exploited is to try and get it covered by world wide patents, then sell the rights to a manufacturer in Asia.

This POS looks like a total non-starter to me.

............ Phil

The fact that you are using relays - and 2 relays have to activate - one after the other to kill the power - significantly delaying the breaking time of the circuit, you have 2 relay coils there - each

240v, which means fine wire - which means fragile - and even worse being in a bathroom or kitchen appliance (wet area) where there is steam, heat and condensation to increase the risk the fine coil wire will corrode and fail.

If EITHER of these 240v relay coils goes open circuit - the protection is defeated and there is no fail-safe mechanism or prior warning of this failure to the user.

Also if someone comes into contact with both the active and neutral simultaneously (the same scenario that an RCD wont protect you if on and insulated floor), this device wont do anything to help protect either. In fact - with the absence of an earth - NOTHING WILL - short of an isolation transformer that can only provide around 30ma or less, and this may even be fatal if connected to the body continuously for any length of time !

With a hair dryer - or other appliance at risk of being immersed, the protective internal shield would have to cover a large area inside the dryer - fully encasing the area around the switch, the element, motor any bare connections to ensure no part of the dryer could be dunked without this "protective shield" area coming into contact with the water BEFORE the mains connection came into contact with the water.

This module would then have to be totally waterproofed, as well as its reset/test buttons (if needed), and incoming mains cord as after it activated, the primary side of the relay would still be live and would possibly also be underwater.

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If you were going to go to all this trouble, you would be better off just having an earth wire inside the appliance (say hair dryer etc) to part 17 (the conductive housing) and use a 3 pin cord and plug - allowing the RCD to do its job with some certainty.

If you had no RCD, then you wouldn't be any less safe than with a 2 pin cord attatched to the unit.

If you still wanted the outer appliance case insulated from earth for greater safety, this earthed area could still be inside and not touchable from the outside. This would cost a hell of a lot less than building up all this - and then having to have the internal conductive housing anyway - to act as a trigger for this proposed device.

This is before we even start discussing the use of relays with mains rated contacts of a sufficient current for conditions such as the load short circuiting, possible surge currents when starting etc etc.

Somehow I dont see all this being done for a dollar. And in this cost-conscious world we now live in - I can't see this being fitted to any cheap consumer goods, unless it was legislated, and I doubt that that is ever gonna happen here.

On 15 May 2005 21:04:28 -0700, "David L. Jones" put finger to keyboard and composed:

I'm not familiar with the relevant standard, but can this device possibly meet the requirements for isolation between housing and neutral? Furthermore, if the active and neutral conductors are reversed in the GPO or in an extension cord, wouldn't the device itself render the appliance unsafe? Granted, Protex may interrupt power to the appliance in this case, but current (6mA?) would need to pass through the user's body in order for it to do so. Elsewhere in the patent application I see a design variation incorporating an optocoupler. Perhaps that is a better approach.

- Franc Zabkar

--
Please remove one 's' from my address when replying by email.

The circuit arrangement looks to me to perform a similar task to that described for the voltage dependant ELCB as described by Pat Ward. The main difference seems to be that the vELCB used a ground referenced metal frame and Protex uses a neutral referenced metal part(17).

QUOTE: ELCB = Earth Leakage Circuit Breaker. There are two types of ELCB, the voltage operated device and the differential current operated device. For the convenience of this article only (and at the risk of causing even more confusion) I will refer to these as vELCB and iELCB. vELCBs were first introduced about sixty years ago and iELCBs were first introduced about forty years ago.

The principle of operation of the vELCB is as follows. Under normal conditions the closed contacts of the vELCB feed the supply current to the load. The load is protected by a metal frame, such as in an electric cooker. The vELCB also has a relay coil, one end of which is connected to the metal frame and one end connected directly to ground. A shock risk will arise if a breakdown in the insulation occurs in the load which causes the metal frame to rise to a voltage above earth. A resultant current will flow from the metalwork through the relay coil to earth and when the frame voltage reaches a dangerous level, e.g. 50 volts, the current flowing through the relay coil will be sufficient to activate the relay thereby causing opening of the supply contacts and removal of the shock risk.

As can be seen from the above description, this type of ELCB is essentially a voltage sensing device intended to detect dangerous touch voltages. The level of shock protection provided by the vELCB was somewhat limited as these devices would not provide shock protection in the event of direct contact with a live part. An additional problem with the vELCB was its tendency to be tripped by earth currents originating in other installations.

Pat Ward is managing director of Western Automation R & D based in Ballinasloe. The company is a specialist designer and manufacturer of RCD products. Pat has been an active member of technical committees in ETCI, IEC and CENELEC since 1991 and has been involved in the drafting of several international standards for RCD & RCMs. He has also participated in working groups within IEC addressing problems of reliability and EMC requirements for RCDs.

The full article is here

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Hi Ross, Any reason why you have set your posts to be not archived? They are useful and it would be nice to have them archived on Google.

Regards Dave :)