Toggling a Solenoid Valve - 60cyc/min - Which ML1200 Output Card?

[skyfox]

I have an application using a MicroLogix 1200 that requires a pneumatic valve to be toggled on/of once per second for 5 minutes each hour. This process runs 24 hours/day. Valve will be energized/De-energized via a Solenoid manifold that supplies the controlling air to the valve. Solenoid manufacturer claims it can handle this frequency. What I am concerned about is the PLC Output card for the MicroLogix used for turning the Solenoid valve on/of at this rate. I am guessing a relay output card won't be able to handle this.

Will a MicroLogix 1762-OB8 Solid-State 24V DC Source output module work for this application?

Thanks

 

[mendonsy]

I would suggest using a separate solid state relay to control the valve and controlling the SSR with the PLC output.
1) You could use an SSR with more current capacity than the valve requires.
2) When the valve fails (it will) you will burn up the SSR instead of the PLC output module. A fuse helps of course!

 

[TConnolly]

SSRs almost always fail ON. If that presents a safety hazard then take it into consideration.

 

[ASF]

I agree with the two posts above. Wire the solenoid via a relay and a fuse. If failing in the "on" state is a concern, use an electromechanical relay, otherwise a solid state relay will get you better longevity.

As to your original question:

Will a MicroLogix 1762-OB8 Solid-State 24V DC Source output module work for this application?

Yes, that's a good output card to use to drive the relay

 

[realolman]

I think a lot depends on your solenoid... we have bimba PFC air cylinders that are shuffled on and off constantly by small bimba solenoids for the past ten years. There have been only a couple solenoid failures and no plc failures ... the cylinders... now that's a different story... they **** out pretty regularly...

I didn't realize that was a bad word... the cylinders fail pretty regularly

 

[osmanmom]

https://www.youtube.com/watch?v=s7wXYgSQaq4

 

[osmanmom]

check attachment