Looking for specific type of keyed switch

[Tharon]

Hmm.

So basically a secondary Safety gate switch that is the "Key" to the cell. That must be removed before the main safety gate to actually get to the caged area can be opened. And must be returned before the caged area can be returned to operation.

I think that may be the working solution. I could use any number of locking safety switches with multiple key options to fit the purpose as well.

I was overthinking when I thought that I needed to carry the specific key with me at all times. I really just need to carry any "Key" to the operation with me at all times. So my initial idea of welding the real key to a tongue switch actuator was just an necessary step. Simply having the tongue switch actuator with me solves the issue.

 

[ASF]

That's right. So your cage is isolated as soon as you remove the key from the control panel, and it can't be de-isolated until the cage is locked and the key back at the control panel. It's pretty standard practice.

You could even remove your actual switch on the cage, as the safety switch is now located at the panel, but by the same token it can't hurt to leave it in. If nothing else it'll give you open/closed indication, which the switch on the fortress key lock can give you locked/unlocked

 

[Tharon]

I had never actually seen it done that way. Every cage/fence I had seen used a single safety gate device (locked or non-locked depending on the machine) attached directly to the gate. Opening the gate isolated power to the device.

I would still keep the gate switch. Just in case something went wrong with the door locking device...

 

[Phil Buchanan]

The AB trapped key system will do what you need. You need the dual key system where the first key is inserted to isolate power and open the gate and only after power is isolated will the second key release and you take it was th you.

The first key stays in the door operator but it can turn and restore power until the second key is inserted and turned.

This is a common setup for high traffic multi robot cells.

 

[Tharon]

The AB trapped key system will do what you need. You need the dual key system where the first key is inserted to isolate power and open the gate and only after power is isolated will the second key release and you take it was th you.

The first key stays in the door operator but it can turn and restore power until the second key is inserted and turned.

This is a common setup for high traffic multi robot cells.

It almost does, except everything in the catalog about it shows that the contacts activate once you turn the key, and it doesn't seem to indicate if you actually remove the key. It doesn't actually unlock until you pull this final key from it's resting place to carry with you.

I'd love to just use one of the key exchange units, and just have one with a handful of keys available for the cell. Unlock the keys, who ever takes a key keeps a key until they are ready to turn everything back on. It won't be able to lock and energize again until all keys are returned. I do realize that is the (a?) standard way of doing things. It is pretty much what we are currently doing, just not with that specific product line.

Are they trying to enforce an unreasonable requirement on me?

 

[mk42]

I've never used it, but I've seen a "keyed" selector switch from Siemens that uses RFID sticks instead of normal key/tumblers. One of the contacts is for if a valid key is inserted. Depending which key you use, it can have up to 4 positions. There is an IO link version that appears to allow a custom ID for each worker as well.

http://w3.siemens.com/mcms/industrial-controls/en/commanding-devices-signaling/sirius-act/switches/Pages/default.aspx?tabcardname=id%20key-operated%20switch

It seems to be an intelligent device, so I'm not quite sure how that fits in with the whole "positively driven" concept for safety.

 

[Tharon]

Well, I finally found a good catalog of the AB Trapped Key system, rather than a brochure and the individual manuals/instructions. And on page 350 (Guardmaster catalog S117-CA001A-EN-P) they have an optional "Ejector Key". A key that appears to push out from the non trapped position.

So it looks like this will be the solution after all.

Thanks for the help on this one.

 

[Eriond]

A low tech solution would be to place a cover of some sort over the key switch that can only fully close if the key is out. Then use a sensor to indicate when the cover is fully closed.

 

[Tharon]

Sat in a meeting today, presented my findings and solutions, thought I had the ultimate solution.

They determined it was not enough. Cause a third party could enter the caged area while unlocked. So now it's down to 100% coverage with pressure mats and scanning devices.

Maybe I'll hire someone to handle just the safety stuff. That will make my life much easier.

 

[Aabeck]

...Maybe I'll hire someone to handle just the safety stuff. That will make my life much easier.

I try to make everything idiot-proof - but then was told I was underestimating the quality of idiots that HR was hiring!

 

[mk42]

I try to make everything idiot-proof - but then was told I was underestimating the quality of idiots that HR was hiring!

HAH!

I was once asked to make some step by step super easy directions for a sales demo. After a runthrough with one of the newest sales guys, I learned two important things:

1. Don't bother with explanatory text. If it isn't in a screenshot, it probably won't get noticed.
2. Even if it is in a screenshot, it still might get ignored.

When he got to the end and it didn't work, we went back through, to see what had gone wrong. When I found the error, I asked if the direction was unclear, or if there is a better way I could have shown it. He said "Oh, no, it's clear enough. I just hadn't thought that page looked important, so I skipped it".