Desperately seeking interlocked door safety application example.

[JesperMP]

Russ,

you are almost correct.
But I cannot find a way to fit a zero speed sensor. The turbine with the large inertia is itself mounted on a rotating arm. Picture yourself a kitchen dough mixer, only very large.

Krk's suggestion with a back-EMF sensing relay is a good idea.
That, or a zero speed sensor on the fan-end of the drive motor.
Or, simply a timer.

I tried to go back to PILZ' website to see if I could find more possibilities. No success, I just cannot find my way through that site.

 

[krk]

Jesper,

The scheme I posted was extracted from this manual:

http://www.pilzsupport.com/downloads.htm

Section: 'Product Range Application Manuals'
Manual: PNOZ
Chapter 4 - Application Examples - Safety Gate Applications)

There's plenty more there to look at...

 

[JesperMP]

Krk,

I have bookmarked that webpage.

Thanks

 

[rsdoran]

Jesper, my apologies, I was not trying to suggest the key trapped units... I just did not pay attention to what page I was on when I copied the link.

I meant to refer to this page with the Guardlocking Interlocking Safety Switches.
http://www.sti.com/switches/swdatash.htm

Look at the TL8012 and read the applications circuit drawing example, it also can incorporate motion detection. http://www.sti.com/switches/TL8012/index.htm

I offered the last too show where to find specific information on using the device, not as a suggestion to use that specific device.

 

[JesperMP]

rsdoran, no need to apologise, I know you want to help.

That is a useful link too, thanks.

edit: STI's products and documentation looks very much like AB's.
Are STI safety products really AB safety products, or is it the other way round ?

 

[agarb]

STI's products and documentation looks very much like AB's.
Are STI safety products really AB safety products, or is it the other way round ?

The exact details are a little fuzzy to me, but I THINK that STI used to re-label Guardmaster products and that A/B purchased Guardmaster 2-3 years (?) ago.

A year or so ago I questioned STI about their long-term future since the A/B acquisition. I was told that A/B would be silly to eliminate STI as STI was one of Guardmaster's largest customers.

Like I said, Details are a little fuzzy so take this for what you paid for it.

 

[rsdoran]

I do not remember all the details but 4-5 years ago AB bought out some companies, one of those was the Guardmaster line of safety plcs.

Some of the other products, like barriers, interlocks, etc AB is relabeling as are other companies. I used a light curtain from SICK that was identical to an AB model, but the cost was less.

It is thought that Moeller makes the Easy and AB relabels it as the PICO, at one time I knew more details and all the "smart relays, were made by other than those labeling them i.e. Moeller, Siemens, AB etc.

I like STI because their only products involve safety and they provide information just for that aspect. I never worried about whether they manufactured the product or not.

 

[AJZ]

Omron just bought/is buying STI. See http://www.automationworld.com/articles/Departments/2208.html

I think it is more like AB is brand labeling products. Some of there relay bases has the name Omron molded in. And just look at AB's DeviceNet Safety IO modules. They are identical to Omrons except for the colour.

 

[dale1627]

Since the subject has been brought up, does anyone know of a "zero speed sensor" that can be hooked straight up to the motors supply leads versus looking at the shaft? All I need is something that shows that the motor has stopped rotating and have an output that I can turn a light off or on with.

Dale

 

[russrmartin]

Dale,

If your motor is run via VFD, you can get that information from the drive I'm certain. Even if the drive is not networked to the PLC or anything else, there are usually outputs which can be configured for various information. That said, I still stand by my statement earlier in the thread that monitoring the motor is not desireable as a safety requirement. I find it hard to believe that it is not possible to monitor the shaft of the load, or the load itself with zero speed sensors. 99.999999% of the time when someone says this, they are simply not getting creative, or are too lazy to find away. That also said, if that .0000001% is correct, then the mechanical design of the equipment is extremely poor.

 

[JesperMP]

Hi Dale.

Go to post #10 and follow Krk's link.
It shows a relay that monitors the back-EMF on the drive motor.

I think that is what you are asking for, not sure about "versus looking at the shaft?".

Anyway, if this is a safety application, you should follow all the steps it takes to make your application safe. Not sure if a lamp is enough.

edit:
russrmartin, I dont understand why a zero speed sensor should be more safe than monitoring the back-EMF.
For my application I prefer the first because I can install it easily. It is certainly possible to install a zero speed sensor on the motor shaft with a little more effort, but I dont understand why it should be more safe.

 

[Gambrinus]

http://ecatalog.telemecanique.com/default.asp?Lg=en

Jesper, it may be too expensive for your task but this equipment is certified for SIL3. You can find more simple solution from Preventa too.

 

[JesperMP]

I just want to safeguard one door, why is it so timeconsuming to figure out ?

OK, I am now getting a lot closer to the stage where I actually have to purchase something.
I have found several vendors, so far so good.

The little problem that I face now is that all the solutions that I have found require me to combine several relays.
There is not a single safety relay in one unit that will do everything for me. I find it to be a little bit complex and probably more expensive too, to have to combine two relays.

I find it strange that there is not a safety relay that is dedicated to my application.
I mean, an inspection door that must not be opened after the moving parts behind the door have come to a standstill, must be a very common application.

I have looked at Pilz, Telemecanique, Siemens, AB, SICK and STI.
They all have a safety relay to hold a door closed until the motor is stopped. But in order to achieve a timedelay, or to sense zero motion, you have to combine it with one more relay.

What about those "multifunction" relays ?
Are they better for my application ?

 

[rsdoran]

I do not understand, thought I provided this already. STI has a Safety Module Timer unit that is for this type application: http://www.sti.com/relays/SR223SMT/index.htm

 

[jstolaruk]

Take a closer look at the Pilz Elog line, specifically the PNOZ E1vP 300. It has an immediate output and a programmable delayed output up to 300 seconds. Just a little FYI, the Elog line provides some simple boolean functions, AND & OR, in category 4. I've used it for some complicated robot perimeter guarding to switch back and forth between robot and manually loading machines.

http://www.pilz.com/downloads/PNOZelog_Technical_Catalogue_GB.pdf