Normally Open, normally closed

[matt1e]

yeah Bernard it's a actually quite surprising how many differing ways contacts etc are symbolised

Matt

 

[JohnW2]

For schematics the following is an informative way to show a relay contact and its function ... The black contact is the contact made when the relay / contactor is not energised. ... The white contact is the contact made when the relay / contactor is energised. ... The wiper / moving contact is drawn to show the normal / quiescent / inactive state of the equipment.

If that were the standard/recognised way of doing it, I agree that would be much better/informative. However, I've personally never seen it used and, as matt1e has said, the almost universal convention is for contacts to be shown in the unenergised position. That being the case, occasional/partial use of your 'better' method would probably cause even more confusion than it avoided!

Kind Regards, John

 

[bernardgreen]

Where it is used a single note on the drawing is all that is needed to explain the system.

 

[JohnW2]

Where it is used a single note on the drawing is all that is needed to explain the system.

Maybe - but people get used (subconciously as well as consciously) to an established convention. I suspect that a single note on some car dashboards indicating that the positions of brake and accelerator pedals had been reversed would not eliminate 'incidents'

Kind Regards, John

 

[matt1e]

Although I'm sure that (as with most things in life) some can get one's head around it better than others, I think you must be joking. With the best will in the world, faced with a diagram showing many relays, all in their unenergised states, some of which are 'normally' energised and some 'normally' unenergised, I don't think there are many people who would not be grateful for some functional annotation such as I described!

absolutely John but unfortunately in the real world you don't always get given that luxury, you don't always get to see any sort of wiring diagrams whatsoever in which case you have to sit and draw/work it out

...but to answer your question It tells me he wasn't sure and wanted to know the answer so asked the question,your point?

Exactly. 'My point' was that this indicates that the answer is not quite as obvious to everyone as you seem to be implying.

no mate I didn't imply anything I answered the ops question and made a comment to Bernard
However an example of someone implying that the answer was obvious to everyone is below

As I said, we all know the answer to that, and Mike was told the answer in both the first and second responses to his question.

 

[JohnW2]

absolutely John but unfortunately in the real world you don't always get given that luxury, you don't always get to see any sort of wiring diagrams whatsoever in which case you have to sit and draw/work it out

No argument with that. I merely pointed out the value of functional annotation, and certainly didn't mean to imply that people always (or necessarily even often) provided it! It would be great if they did.

Exactly. 'My point' was that this indicates that the answer is not quite as obvious to everyone as you seem to be implying.

no mate I didn't imply anything I answered the ops question and made a comment to Bernard However an example of someone implying that the answer was obvious to everyone is below

As I said, we all know the answer to that, and Mike was told the answer in both the first and second responses to his question.

Now you're quibbling, since I'm sure you know what I meant! That was a 'royal we', referring to those of us 'in the know'. I've also just noticed that I failed to give you credit for also having confirmed the correct answer, in the third response - my apologies.

It's amazing how these exchanges can seemingly develop a life of their own. I merely ('innocently', I thought) agreed with Bernard's comment that, IME, it is common to see people (obviously not those 'in the know') getting confused about 'normally' open and closed contacts (something I still believe to be true), but it's already developed into about a page of exchanges, and may not even have finished yet!

Kind Regards, John

 

[matt1e]

Course I'm quibbling mate I'm onto my third mid life crisis at The mo
But yes you're right John its amazing how many questions are asked on here get answered on first reply in the thread then escalate into pages and pages
I suppose most of us are as guilty as each other
Off out now to a do so shall humbly retire from this post
Enjoy the rest of this fine day peeps ( well its a mighty fine day up here)

Matt

 

[JohnW2]

But yes you're right John its amazing how many questions are asked on here get answered on first reply in the thread then escalate into pages and pages I suppose most of us are as guilty as each other

Yes, I'm sure we are, and I'm undoubtedly more guilty than many. However, once the OP has been answered, the subsequent 'pages and pages' of incidental stuff can sometimes be interesting and worthwhile. For anyone only interested in the answer to the OP, I doubt whether it is often worth looking beyond the first page!

Off out now to a do so shall humbly retire from this post Enjoy the rest of this fine day peeps ( well its a mighty fine day up here)

I hope you have a good time at the do, and enoy the fine evening. It's actually been overcast for most of the day down here, so not so exciting - but I've just opened a bottle and ordered the takeaway, so I'm set up for the evening!

Cheers, John

 

[ban-all-sheds]

nearly always without exception

Well, which?

 

[JohnW2]

nearly always without exception

Well, which?

I also wondered (and personally would probably have said 'nearly always'), but then when I read ...

it's a actually quite surprising how many differing ways contacts etc are symbolised

... I found myself wondering what on earth he had meant

Kind Regards, John

 

[matt1e]

nearly always without exception

Well, which?

I also wondered (and personally would probably have said 'nearly always'), but then when I read ...

it's a actually quite surprising how many differing ways contacts etc are symbolised

... I found myself wondering what on earth he had meant

Kind Regards, John

BAS What I mean is , if there is one drawing provided whether in a manual, affixed on the back of a panel door or whatever, it will always without exception show the circuit un-energised.
Now and again (rarely) I have come across documentation for a machine that includes extra drawings that show the state of the circuit functioning
I do apologise for my poor use of the written word and the fact that my seemingly contradictory sentence confused you, it may help if you read the whole thread again as I think you will probably get the jist of things, you seem intelligent enough.
I will try to do better from now on

John, I thought that sentence was simple enough to understand and what it has to do with bas's comment is beyond me, but I'll explain it anyway
Sometimes I see relay contacts symbolised as per Bernard's post
On other drawings they are symbolised as I would symbolise a capacitor (with a diagonal drawn through to indicate NC)
Sometimes they are drawn as I would draw a push to make or push to break switch
Same with the coils but I think you know what I mean now.

Matt

 

[JohnW2]

[John, I thought that sentence was simple enough to understand and what it has to do with bas's comment is beyond me, but I'll explain it anyway
Sometimes I see relay contacts symbolised as per Bernard's post

Sorry if I was not clear enough. It wasn't directly related to BAS's comment. Having agreed with him that "nearly always without exception" was far from clear, I then went on to indicate that (assuming your comment meant something like "nearly always"), it seemed a little surprising that you then went on to say that there were "many ways of symbolising contacts", including the method described by Bernard, in which the contacts (well, the 'wiper' thereof) will, in some cases, be shown in the unenergised postion.

Anyway, I think we can probably agree that the crucial thing is that whatever symbol convention or words are used, the meaning must be clear to the reader (with notes, if necessary, as required). Anything beyond that is more a matter of convenience.

I hope you had a good do last night!

Kind Regards, John

 

[matt1e]

I hope you had a good do last night!

Kind Regards, John

Great thanks and still recovering, and for some reason I thought I could dance amazingly last night, I'm dreading the photo's if any

Matt

 

[JohnW2]

Great thanks and still recovering, and for some reason I thought I could dance amazingly last night, I'm dreading the photo's if any

Don't worry about the the photos, worry about any videos that were taken

Kind Regards, John

 

[ban-all-sheds]

BAS What I mean is , if there is one drawing provided whether in a manual, affixed on the back of a panel door or whatever, it will always without exception show the circuit un-energised.

Ah.

I think "always" and "without exception" mean the same thing.