adccommunitymod (AutomationDirect) asked a question.
Created Date: May 11,2018
Created By: dcheser
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I have a Productivity 3000 series system with a P3-16TD2 Output module, 16 Point sourcing 24VDC. The module works fine until an E-stop is hit. A contact from an E-stop relay drops power to the module, when the E-stop condition is cleared/reset the ouputs are all fried. Replace the module and everything works until the next E-stop condition. Anyone have any thoughts? The ouput module has 12, 24VDC solenoids connected and a maximum of 4 solenoids can fire at one time. System has been in service for 1.5 years and we have had 4-Estop conditions resulting in 4 modules ruined.
Created Date: May 11,2018
Created by: dcheser
I have a Productivity 3000 series system with a P3-16TD2 Output module, 16 Point sourcing 24VDC. The module works fine until an E-stop is hit. A contact from an E-stop relay drops power to the module, when the E-stop condition is cleared/reset the ouputs are all fried. Replace the module and everything works until the next E-stop condition. Anyone have any thoughts? The ouput module has 12, 24VDC solenoids connected and a maximum of 4 solenoids can fire at one time. System has been in service for 1.5 years and we have had 4-Estop conditions resulting in 4 modules ruined.
Created Date: May 11,2018
Created by: RogerR
Does the PLC have the outputs turned on when the power is applied after the Estop Reset?
If so and the power fluctuated from contact bounce, it may oscillate the outputs rapidly and generate a large voltage for a very brief period.
This may exceed the voltage range on the module.
Created Date: May 11,2018
Created by: dcheser
Yes, Outputs could be energized when the E-stop is reset but I could put a time delay between the E-stop clearing and the Outputs being re-energized to see if that corrects the problem. That would allow the module time to power up before firing any outputs.
Created Date: May 11,2018
Created by: Tech_9282
Just to clarify, when the event occurs with only 4 outputs active after the reset all 32 outputs have failed? What sort of suppression do you have around those DC solenoids?
Created Date: May 11,2018
Created by: dcheser
No suppresion is being used. All equipment in the panel is rated Class 1 Division 2 and panel is in a Class 1 Div 2 Area. I am unaware of any suppressors that are rated C1D2.
Created Date: May 11,2018
Created by: MikeN
I dout it is specifically the solenoids opening that is killing the module, as if it were then I woulds think only the channels that had been active at the time of power disconnect would be the ones fried. To me it seems more likely that by suddenly disconnecting power to the module is what is killing it. Whether by a spike in your power itself or something to do with the card having power and suddenly the circuit is broken and it has nowhere for the power to go.
Is it correct practice to completely disconnect power to the PLC module itself? The machines we have that came with PLCs from the factory do not lose PLC power on an E-Stop. All outputs are forced off sure, but the PLC itself still keeps power.
Created Date: May 12,2018
Created by: durallymax
Yes, Outputs could be energized when the E-stop is reset but I could put a time delay between the E-stop clearing and the Outputs being re-energized to see if that corrects the problem. That would allow the module time to power up before firing any outputs.
I'm not an electrician but was under the impression that there needed to be a second action after an e-stop reset.
What is the reason for cutting power to PLC vs maybe cutting off common to coils and sending E-stop to PLC to interrupt outputs so they can't be re-energized on reset?
Created Date: May 12,2018
Created by: Ridgeline Mach
I'm not an electrician but was under the impression that there needed to be a second action after an e-stop reset.
What is the reason for cutting power to PLC vs maybe cutting off common to coils and sending E-stop to PLC to interrupt outputs so they can't be re-energized on reset?
Dropping out the commons to the coils would be odd. If I'm understanding what the OP does, they drop out the +24vdc to the +24vdc terminal of the output module (this is how I do it, but with P2K output modules) when an E-stop is invoked.
I wonder if there are any coil loads (pneumatic valves, motor contactors, relays) on the outputs that don't have suppression? Coil loads can damage solid-state outputs if they don't have suppression.
Created Date: May 12,2018
Created by: kewakl
Dropping out the commons to the coils would be odd. If I'm understanding what the OP does, they drop out the +24vdc to the +24vdc terminal of the output module (this is how I do it, but with P2K output modules) when an E-stop is invoked.
I wonder if their are any coil loads (pneumatic valves, motor contactors, relays) on the outputs that don't have suppression? Coil loads can damage solid-state outputs if they don't have suppression.
OP mentioned something about class 1div 2 area. Unsure of approriate suppression for c1d2 area
Created Date: May 12,2018
Created by: Ridgeline Mach
OP mentioned something about class 1div 2 area. Unsure of approriate suppression for c1d2 area
I look it up to mean an explosion proof environment? I am unsure how that has anything to do with outputs failing.
When I have quoted explosion proof equipment, the enclosures were cast-iron, and all conduits to the enclosure had to be epoxied to isolate it from external devices if there was a fire.
What I wonder is, if the module is being damaged when the E-stop is invoked, not from when power is re-applied.