Safety circuit OSSD

Dear all,


Is it permitted to wire a normal safety button in series with OSSD outputs? (And will it work)



OSSD 1 => NC contact 1 button => OSSD input 1 safety relay
OSSD 2 => NC contact 2 button => OSSD input 2 safety relay


Thanking you in advance!

Hi and Welcome to the Forum!

Let's start with this...

SD23 said:

...normal safety button...

Click to expand...

Do you believe such a thing to exist?
If so, then what makes it Safety Rated?

Or...

Are you describing what you wish it to be?
If so, then is it really Safety Rated?

If it is not Safety Rated, then do you think it should be permitted in series between a Safety Rated Output Signal-Switching Device (OSSD) and its intended Safety Input device (Eg: Safety Relay)?

Also, what will "work" is not necessarily what will be "Control Reliable", in Safety terms.

Regards,
George

SD23 said:

Is it permitted to wire a normal safety button in series with OSSD outputs? (And will it work)

OSSD 1 => NC contact 1 button => OSSD input 1 safety relay
OSSD 2 => NC contact 2 button => OSSD input 2 safety relay

Click to expand...

Yes this will work and is generally permitted--of course it depends on the details of your specific application. As technology advances, however, the idea of putting multiple safety devices in series is becoming outdated. The concern is "fault masking"--see post #8 of this thread for a basic explanation.

Without knowing the full details of your application and working components, I don't see how I can truly answer your question. we can only answer in regards to what you have provided and failed to tell us.

Thanks for all the answers.

@Geospark, I'm using a standard Schneider emergency button so that should be fine.

The faultmasking aspect is something to not neglect in further projects, thanks for the hint!