Allen Bradley Gaurdmaster Safety Relay

[bwiring]

I am having troubles with a AB Gaurdmaster Safety relay (440R-D22R2). The relay will fault out for no apparent reason. Sometimes it will run fine for 2-3 weeks and then fault one time in a day. Sometimes when it faults it will fault 10 times in a row. Connected to s11-s22 and s12-s21 are two safety mats wired in series.Connected to s32 and s42 are magnetic door switches (440n Sensa Gaurd non-contact door switches) fed from +24vdc. Has anyone had any problems with these devices of have any suggestions on what could be the issue. I have checked and rechecked the wiring.
Thanks

 

[califflash]

See AB Technote http://www.redlion.net/Support/TechNotes/ProcessControl/TNOI39.pdf

My guess would be that you are having issues with the capacitance of the 2 safety mats. I would try moving the sensa guards to a separate safety relay that is cascaded from the one you have now and putting 1 safety mat on 1 input. The 24VDC feeding the sensa guards should not cause a fault, but I believe it would be better if you used S11 & S21 to feed those sensors.

I haven't seen this problem first hand. I assume from your post that you cannot find any sequence of inputs to repeatably create this problem. And you are getting a flashing red fault light, correct? Or is this a situation where the input will not come on?

 

[marcel8u]

what do you mean fault? it has fault code on the relay or you just mean stopping the machine and coming up safety fault on HMI?

 

[bwiring]

AB says that the sensa guards have to be powered from 24vdc not the test outputs. The mats are cross wired from the test outputs to the inputs as per AB. The relay is looking for a fault between the two ckts. to say that there is pressure on the mats.

Could you explain more about the capacitance between the two mats, how it could be generated.

By fault I mean a red flashing light on the "power/fault" light. It is odd that the faults occur with such randomness and I cannot do anything to make the fault happen.

Thanks for your help and time.

 

[marcel8u]

I could't find a thing about the red LED status. I believe this is the actual module faulting out and not the Stop circuit. IF the Stop circuit opens you should just see the 2 INs not made and the Output off. Has it just started or has it been an issue all along? These look like the older style we had to up grade ours to the newer style. We always had issues with it thinking there was an open circuit and stopping the machine.

 

[califflash]

Referring to the technote I previously posted, in addition to some other knowledge base articles I've lost the links to, a safety mat is basically a capictor. In some cases, if the mat is large enough or you have multiple large mats wired in series the controller could fault. What all those conditions are I don't know. The information I've read from ab implies that this could be a problem for some people.

Referring to the sensaguard switches, the ones I have used are dual OSSD output utilizing 3 power sources. One power source is for the electronics of the sensor. The other 2 each power the respective OSSD output, so that you Cavan maintain cross fault detection. In many cases the OSSD power can be supplied by the safety relay. When set up using a safety mat I'm not sure if using terminals 11 & 21 to power the OSSD's would trigger a fault or not. You could always disconnect them, then reconfigure your relay to check.

One other thing to note about this situation is this. You must have the safety mat correctly wired into the relay before you configure it. I have configured them without the safety mat and the relay will fault when you step on the mat.

If you continue to have trouble please post a wiring diagram and your relay settings.

 

[marcel8u]

Referring your technote has nothing to do with AB saftey relays.. give us the correct link

 

[califflash]

It seems I gave the wrong link. Search the ab knowledge awe for technote 506016

 

[Tangi]

I also have installed 440R-D22R2 safety relays with mats connected, also getting fault trips for no apparent reason.
Probably once or twice per 10 hour shift, mats are activated around 800-900 times during this period.

We have two relays connected to mats.
Relay one has one 750mm X 500mm Mat connected.
Relay 2 has one 750mm X 500mm and one 500mm X 500mm mats connected.

Both relays are tripping on a "red five flash" fault on pwr/status indicator, which the manual states as
"Output test failed on L11"
The problem is that the L11 is not used or connected on either relay.

bwiring did you resolve your problem?


Thanks