3-Position keyed selector switch

I am implementing a project using a Do-More PLC from AutomationDirect.com (Koyo manufactured) and one feature that we are tying to incorporate is a mode-selection. There would be a 3-position selector switch with a key that has three modes: Manual, Auto, and Off. "Manual" and "Auto" would go as inputs into the PLC, and "Off" would potentially energize a relay that switches off the 24VDC power to an actuator. The problem is that every single 3-position key-switch that i have found only has two positions that can be shorted to common, with the third position (usually the center) not being connected to anything. Does anybody know of a 3-position key-switch that actually allows the common terminal to be shorted to three different selections? To further illustrate my point I have drawn up a quick schematic of what I am looking for. Thanks!

Why not parallel off your #1 and #3 contacts to the relay coil, and run the actuator through the NO contacts instead of NC? Then you'd have power to the actuator with the switch in the left or right position, but not in 'Off'.

Get a SS which has a NO and a NC contact on each position. Use the 2 NC in series to control your relay.

kolyur said:

Why not parallel off your #1 and #3 contacts to the relay coil, and run the actuator through the NO contacts instead of NC? Then you'd have power to the actuator with the switch in the left or right position, but not in 'Off'.

Click to expand...

He'd have to add 2 more relays to keep from tying his 2 inputs together, or have a second set of contacts on each side of the switch

You might try C3 Controls cam switches. They have a key operator and their "multi-step" configuration should do what you want.

T Gibbs said:

He'd have to add 2 more relays to keep from tying his 2 inputs together, or have a second set of contacts on each side of the switch

Click to expand...

Yeah good point. Putting extra contacts on the switch as you suggested would probably be the simplest solution.

PLC output

You have two inputs into the PLC. Use logic in the PLC to turn on the relay with an output.

just the cowboy said:

You have two inputs into the PLC. Use logic in the PLC to turn on the relay with an output.

Click to expand...

I thought that, too, but I think he's trying to avoid using the PLC to turn off the actuator.

Allen Bradley makes a 3 pos switch with a contact in each position.
800T-????, sorry, can't remember the rest.

james

What about -

http://www.ab.com/en/epub/catalogs/12768/229240/229244/2531083/Selector-Switches.html

800T-N32KF4B

Just ignore position four.

Most NEMA rated selector switches let you add contact blocks in a second row, and many a third row. Here is an example: http://www.automationdirect.com/adc...luminated_-a-_Non-Illuminated/LED/GCX1265-24L

If you can't figure out an arrangement on your own I suggest you contact tech support at AutomationDirect for help or contact your local Allen Bradley or Eaton or Schneider distributor.

When I used to do things like this I would use one row of contacts for the hardwired circuits and one for the PLC. If it wasn't in manual or auto then the PLC logic indicated it was in off.

Look at these:
http://www.schneider-electric.com/e...er=business-1-industrial-automation---control

I would recommend this one:
http://www.schneider-electric.com/e...-automation---control&parent-category-id=4800

Get an extra contact in the middle slot, indicating NOT LEFT AND NOT RIGHT.
If you need to separate everything, perhaps CAM switch would be better

Energizing a relay, in the off position, to kill an actuator isn't best practice to say the least. Would be better to switch the relay on in auto or manual with contact blocks in parallel IF the application doesn't require a real safety circuit.

Then just stack contacts for the plc inputs. Or you could take one input off the relay and just use a switch contact for auto.