E-Stop Circuits

Kilowatt#76

Member
Join Date
May 2018
Location
Rock Hill, SC
Posts
2
Hi,

I'm not sure if this is the correct forum for this. I had a question about safety relays. We have 2 machines that have their own safety relay. Is it possible to connect the 2 safety relays together and make it like one machine? So for example, if I push an E-stop on machine #1, machine #2 would also be E-stopped. I'm using Allen-Bradley's safety relays, 440R-M23088.

Thanks,
Kilowatt#76
 
Welcome to the Forum!

Yes, you could interlock the two EStop relays and this is a pretty common practice.

For a Master-Slave 'relationship' you would connect a Safety Output (or 'dry contact') of the 'Master' relay to a Safety Input of the 'Slave' relay.

The 'Master' EStop relay will need to be Reset first in order for the 'Slave' to become Reset capable too; in your particular scenario, machine #1 EStop relay would be the 'Master' and machine #2 EStop relay would be the 'Slave'.

Refer to the circuitry diagram of your EStop devices for the physical implementation.
 
Thank you!

Can you please show me an example wiring diagram of this. I will be using redudant E-stop pushbuttons, both E-stops will have 2 N.C. and 1 N.O. for PLC input.
 
It depends of the existing EStop circuitry.
If you are already using both Safety Inputs for the machine #2 Safety Relay (S11, S12, S21 and S22 connected to a 2 NC EStop PB) you will not be able to interlock the machine #2 EStop relay to machine #1 EStop Relay.

If you are using only one Safety Input (S11, S12 connected to a 1NC EStop PB) then you could connect machine #1 Safety Relay terminals 37 and 38 (or 47 and 48) to machine #2 EStop Relay terminals S21 and S22; the 37/38 and 47/48 outputs are time delayed.

Refer to Typical Wiring Diagrams at the bottom left of:

https://www.mc-mc.com/ASSETS/DOCUMENTS/ITEMS/EN/Specification Sheet_39-s117-ca505_-en-p.pdf
 
Last edited:

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