Which Type of Limit Switch

[EddyCurrent]

Ray,
I got these from your earlier threads;



It looks like your power supply is this one;
http://www.zappautomation.co.uk/elec...-supply-7.html

You are using the 36v to power the steppers and the 5v to power the breakout board, you also have a 24v supply in there for the Pilz ?
Because the 36v is used for the steppers I would suggest not using that for the proximity switches as it could contain a lot of electrical noise, instead I would use the 24v supply provided it is DC and not AC.

Also, off topic, have you cut any of those nuts yet ? what tooling do you intend to use for a 9 gauge string slot ?

[cropwell]

This is maybe a daft question, but do not see a 24v supply for the PILZ unless it is that box to the left of it on the DIN rail.
.
What do these safety relays do that makes them cost £360? I can see a 4 pole contactor, which is presumably 3 phases and aux and I also presume there is some sort of RCCB and E-stop interface. If you are not running 3-phase, then it seems an overkill ('scuse the ironic pun).
.
An RCCB a break switch and NVR switch in series, would seem all that is needed for a good level of safety on single phase 240v.

[Clive S]

This is maybe a daft question, but do not see a 24v supply for the PILZ unless it is that box to the left of it on the DIN rail.
.
What do these safety relays do that makes them cost £360? I can see a 4 pole contactor, which is presumably 3 phases and aux and I also presume there is some sort of RCCB and E-stop interface. If you are not running 3-phase, then it seems an overkill ('scuse the ironic pun).
.
An RCCB a break switch and NVR switch in series, would seem all that is needed for a good level of safety on single phase 240v.

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. ..Clive

[JAZZCNC]

What do these safety relays do that makes them cost £360?

They empty your wallet sharpish. .. Lol

The Narrow white box next to Pilz relay is a 24V Balluf PSU. There is no Contacter in there that I can see.?

[manofgresley]

Yes it is a 24 volt Transformer, i fitted the Pilz on good advice off this site, cost £36.00. Ray

This is maybe a daft question, but do not see a 24v supply for the PILZ unless it is that box to the left of it on the DIN rail.
.
What do these safety relays do that makes them cost £360? I can see a 4 pole contactor, which is presumably 3 phases and aux and I also presume there is some sort of RCCB and E-stop interface. If you are not running 3-phase, then it seems an overkill ('scuse the ironic pun).
.
An RCCB a break switch and NVR switch in series, would seem all that is needed for a good level of safety on single phase 240v.

[manofgresley]

Now sorted, Many thanks, once again to all who have helped me with there advice and wisdom.

Ray

[cropwell]

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 !

[EddyCurrent]

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 !

They are designed for industrial use, nobody like us pays full price, here's one for example £25;

http://www.ebay.co.uk/itm/PILZ-safet...item2ed3f7fc61

[cropwell]

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.

[Neale]

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.