Interlock, E stop and saftey relay.

neeraj194

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Mar 2018
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Hi all i'm a beginner in automation filed I need help with safety relays.
How to integrate interlocking switches(dual channel) and E stop(dual channel) to cut off a single motor using safety relay.
 
Short answer:

read the manual of the safety-relay. By the way what safety relay do you use? And the other components: interlock switches, E-stops and also the relays?

Fence-guarding and E-stop should be different safety relays (classic safety-relay) but if you use programmable safety-relay (eg pnoz multi) of an safety-relay with safety-IO-cards than you can combine them in one 'safety-relay-system'.

Long answer:

Safety requires some good training provinding you knowledge. eg. The relay('s) should have an NC iintegrated inside the relay (no auxillary-block allowed) and this according to a certain standard (mirror-contacts).

You (and best also others) should make a risc-assessment. A part of this assessment will give you information if this safety-relay should be wired as a single of a redundant system.

Not following the long road can make you end up in jail if something goes wrong.

But here you can ask question but there will be many things to think about if you want to do it professionaly.
 
Interlocks, E stop and saftey relay.

thank you ivan.maenen for the reply. Actually this is an upcoming project we havent yet selected the components. I've gone through siemens safety relay manuals and what i found was,I need 2 contactor's if I am using E stop in a dual channel manner (using 2 NC contacts ). I'm also using interlocks to cut off the same motor so do i need another set of safety relay and contactors ?
 
thank you ivan.maenen for the reply. Actually this is an upcoming project we havent yet selected the components. I've gone through siemens safety relay manuals and what i found was,I need 2 contactor's if I am using E stop in a dual channel manner (using 2 NC contacts ). I'm also using interlocks to cut off the same motor so do i need another set of safety relay and contactors ?

Because interlocking 'fence-guarding' and E-stops serve a safety function: yes.

If you are using classic saftey relays you should use a (third) master-safety-relay. Because of this extra cost you can start to think about a modulair-safety relay if you have 3 or 4 safety functions.

I atteched 3 pdf's:

master-SR_1 and _2: normal situation (1 safty relay, mind you the photo is an example and not belonging to the schematic's involved)
master-SR_3: the master safety relay-concept
 
Last edited:
Have you done a Risk Assessment on the system? The difference between a PLe Category 1 stop, and PLc Category 0 stop can be a number of parts, and a lot of cost.

What is the outcome of your Risk Assessment? What Stop Category does the application require? Which architecture category does it require?
 

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