I must be going blind as I don't see a 4 pole contactor the schematic is showing 240V I have picked up those pilz for less than £10 on ebay. ..CliveQuote:
Originally Posted by cropwell
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I must be going blind as I don't see a 4 pole contactor the schematic is showing 240V I have picked up those pilz for less than £10 on ebay. ..CliveQuote:
Originally Posted by cropwell
They empty your wallet sharpish. .. LolQuote:
Originally Posted by cropwell
The Narrow white box next to Pilz relay is a 24V Balluf PSU. There is no Contacter in there that I can see.?
Yes it is a 24 volt Transformer, i fitted the Pilz on good advice off this site, cost £36.00. RayQuote:
Originally Posted by cropwell
Now sorted, Many thanks, once again to all who have helped me with there advice and wisdom.
Ray
The contactor I was referring to seems to be built into the safety relay. Then there is also an e-stop input and presumably other safety measures built in. I looked at the PILZ website for some information, but just got boggled with detail. They quote £360 for the PNOZ. I'd want it in gold for that money !:whistle:
They are designed for industrial use, nobody like us pays full price, here's one for example £25;Quote:
Originally Posted by cropwell
http://www.ebay.co.uk/itm/PILZ-safet...item2ed3f7fc61
I understand the pricing policy. If you are selling to a large industry customer you have to provide support and have product liability. They have to be at such a price that they can just swap out any problematic unit. Also the employer has to have employee liability and that would probably preclude buying from an 'unreliable ' source.
I wouldn't mind if anyone could tell me the modular functionality of such a unit, and what qualifies it to have the title 'safety relay'.
I'll probably include one in my next build.
Looking at the one I have, the key thing about it seems to be duplication. There are effectively two relays which can be wired in parallel or, ideally, driven via a double-pole e-stop switch. Then the relay n/o contacts are in series so either relay dropping out will open the circuit. It's a bit more complicated than that, of course, depending on which model relay you get, but that's the heart of it and how it can reasonably claim to be a "safety" relay. I guess that build quality is better than a cheap relay from Maplin as well.
Thanks Neal,
I'll only take issue with one thing, I find 'cheap' and 'Maplin' don't sit easily in the same sentence. :rolleyes:
Rob
It's about meeting certain standards;Quote:
Originally Posted by cropwell
"PNOZ safety relays comply with international standards and are approved by BG and international certification bodies. They provide maximum safety up to and including Category 4 in accordance with EN 954-1, Performance Level "e" in accordance with prEN ISO 13849-1 and SIL 3 in accordance with IEC 62061. "
Manufacturers have to demonstrate their product meets these standards and this can be a costly and lengthy process.
These things matter under scenarios like, legislation, reliability, safety, compensation, prosecution, etc. So if these is an accident for example, you may need to demonstrate that you or your company have exercised 'Due Care' by using components that comply with the required safety category.
These devices are also called 'Safety Monitoring Relays' there are basically 4 safety categories, it's up to the owner to work out which category is applicable to their particular application, this information is used;
http://www.pilz.com/en-GB/knowhow/st...articles/00238
You then select a safety relay that meets the required category and also has the required electrical characteristics for the application.
Further reading would also be this, http://en.wikipedia.org/wiki/Safety_Integrity_Level
.Quote:
Originally Posted by EddyCurrent
Thanks for the references Eddy, I had a look at them, but I gave up trying to understand those sort of documents when I retired in 1999.
They may be relevant for a corporate engineer, but I am just a hobby player.
.
That's all well and good, but how do they get to be £25 on eBay (if they haven't fallen off the back of a stores shelf :whistle:).
.
I'm not an employee and I don't need to have duty of care over some moron who is bound for self destruction by his own stupidity. All I need is that if I have to bang E-stop the damn machine stops PDQ, and if it can't account for all the electricity going in through the live and coming out through the neutral, I also need it to isolate itself until the leak is fixed (within 30 milliseconds, preferably a lot less, if it is more than 30 milliamps going through me). There may be other requirements yet to be determined.
.
As a silly aside ;- Pilz is German for Mushroom.
.
Thanks anyway for the input, but it is far too heavy for my butterfly brain.
Maybe the mushroom reference is to do with the red botton on an E/Stop, typically referred to as a mushroom.
The one I bought was from a place that had closed and they were clearing out the stores.
You are correct about these not being applicable to hobby use but when you consider what's inside it can work out cheaper than standard relays, timers, etc.
Also I value my health so I'm prepared to go the extra mile to preserve it.
Mine was cheap because it's an obsolete model and therefore probably no longer certified for new build commercial equipment. Box was damaged as well but relay looks in perfect condition. What I haven't seen cheap on eBay are the double-pole e-stop switches although I'm not too worried as I reckon that a n/c contact is more likely to work when it gets thumped in a hurry than n/o. While safety is important, I'm not building a machine that will be used by a numpty on piecework. But we all draw lines in different places...