safety relay needed????
safety relay needed????
(OP)
We have a large machine with two discs rotating at high speed, to shut down the machine if it becomes unbalanced a vibration switch is to be fitted. I have to send a signal to an s7 plc via an et200 rio panel to signal that the vibration switch has been triggered. Is it o.k to let the plc shutdown the machine or do i need to use a safety relay to open a contact and drop out the contactor supply and set the signal to the plc as I only have one shutdown contact on the vibration switch.
I'd appreciate any advice ty.
I'd appreciate any advice ty.





RE: safety relay needed????
RE: safety relay needed????
As you are protecting machinery rather than people with the vibration switch you do not need a safety relay.
It is possible that you need a safety relay and have to worry about bringing the discs to stop quickly in order to provide personal safety, but thats another discussion.
Also, a safety relay allways works on two signals (or two contacts in the same sensor), so you cannot connect that vibration switch to a safety relay anyway.
I would let the PLC evaluate the signal from the vibration switch. Its is much easier to interlock it with your control and to program it to ignore the switch during startup etc.
RE: safety relay needed????
RE: safety relay needed????
Snoogie
RE: safety relay needed????