PLC Shutting Down.

[thetech]

I'm working with a Automation Direct (P3-550) - 16in - 16 out. I have a input that sends an output to a relay to turn on a Operator Interface (Red Lion). The problem is when the Operator Interface tries to turn on the PLC shuts down and does a reboot. I'm using a good 10amp 24volt power supply, so lack of power is not the problem. What I did to fix it was put a capacitor across the P3-550 power supply inputs and the problem went away.

My question is what should be the correct value of capacitor should I use?

And is this the right step to fix this problem?

Thanks
TheTech

 

[albertabound]

A reaonably good power supply should have capacity to avoid such. You may want to review the supply connections as you may have a voltage drop at some point. you don't want to daisy chain the supplies, rather bring them seperately off the supply for each device.

 

[thetech]

I do have the PLC and the Operator Interface daisy chained. But I figured with #14 wire and 10amp supply I would not have any trouble. I ques I was wrong. I'll run a [FONT=&quot]separate wire for each.

Thanks for the tip.

That was really quick.


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[David_Emmerich]

Another thing to remember is that while 14 ga Cu will handle 15 amp at 120 vac, you need to derate it by at least 50 % to 7 amps at 12 vdc...and over kill on the main power wiring can go a long way to 'fix' design boo-boo's...

 

[Tharon]

Another thing to remember is that while 14 ga Cu will handle 15 amp at 120 vac, you need to derate it by at least 50 % to 7 amps at 12 vdc.

I've never heard of this. And I'm pretty sure there is nothing in the code books on it.