How to wire in third E-stop

[earlybird04]

Could someone help me to wire in a third E-stop into an existing system via a pilz relay?

 

[newfutile]

If its a push to break emergency stop it should be wired in series with the existing ones

 

[earlybird04]

How would i show that on the drawing?

 

[Darkwood]

An understanding of the appropriate regulations and practices are essential when dealing with safety critical systems here, in asking what is a basic question to those in this field it would suggest you should not be taking such a job.

-Unless you specify this kind of work it is highly unlikely your insurance will cover you for it.
-In adding to the system you take on board the responsibilities of the safety of the machine and its operators and that includes identifying and rectifying existing compliance issues if the machine is not up to the latest standards.
-You will also need to show a risk assessment regarding the machine and include the additional E-Stop and why it is required or requested.
-An understanding of the safety relay, the wiring method and how to test it for correct function and fault events to confirm it operates in all states safely will also be needed and documented here.

I may sound a bit like the fun police here but be extremely cautious of taking on any kind of work which involves safety critical control systems, especially when you are actually altering them, even when the actual addition may be a very simple task in itself which it looks to be from the wiring schematics.

 

[netblindpaul]

That drawing is 2018, and thus the machine is CE marked, thus covered by the law, in the UK SMSR.
To modify you need to comply with PUWER at least, and you would be taking on the design and liability for the safety function yourself.
PUWER guides you to SMSR which guides you to the HD's.
So for an s-stop, there would be ISO 12100, ISO 13850, ISO 13849-1, ISO 13849-2, EN 60204-1, plus the machine instructions to re-write and update the technical file, which the machine OEM is not legally obliged to provide, so you would need to reverse engineer the situation yourself.
This all applies regardless of whether the machine owner does the work or gets someone else to do it.
It's the law.
The relevant laws have a lot closer links legally to the HD's than BS 7671 does to EAWR.
Once you have done the design calls and documented them including the 13849-2 validation, then you would proceed with the work on-site, it's not acceptable to do the work then document it because you might come unstuck like I have found several times when doing after the fact validations and the design doesn't comply!
Doing a 13849-2 validation on a used machine is also a nightmare because you don't know how far through the B10d lifetime the existing components are.

BREXIT doesn't change anything, apart from you could argue that you now need to UKCA mark it and use the DS's rather than the HD's, the technical requirements are identical.

As DW says above, beware of your insurance as you are into the design, manufacture and supply of a product, here. Most electrical contractors policies do not cover anything outside the scope of BS 7671, and this is.
Clause 1102, xi of BS 7671 puts this out of scope.

Also as DW says, not trying to spoil your fun, just warning you what the ramifications are.