RS-485 Surge Protection

[TonyR68]

Hi All,

I’m preparing to add RS-485 Surge protection to my 2 IntelliPro VSF pumps, MasterTemp and IntelliChem data lines. I will use the SerialComm RS-485 Surge Protector as recommended here. My plan is to add a ground bus (top right in picture below) to handle all the additional ground wires (8, for the 4 surge suppressors), 12 awg (flexible, stranded) for ground wires and excess wire from my VSF communication cable to reconnect the surge suppressors back to the IntelliCenter control boards.

Is this plan the best way to go? I’m going to add many additional wires and the suppressors to a relatively small area. Is the ground bus approach and placement ok? Should I rather place the suppressors for the MasterTemp and IntelliChem in their units and not inside the IntelliCenter Control Power Center? Other considerations?

Thanks,

Tony

 

[mas985]

Do you have AC surge protection?

Electrical Surge Protection - Further Reading

www.troublefreepool.com

You need that to protect the VS drives and the rest of your equipment. I am not sure specific surge protection for RS-485 is even necessary once the mains are surge protected.

 

[Ahultin]

Do you have AC surge protection?

Electrical Surge Protection - Further Reading

www.troublefreepool.com

You need that to protect the VS drives and the rest of your equipment. I am not sure specific surge protection for RS-485 is even necessary once the mains are surge protected.

Yes, I beleive there have been several incidents where things are taken out from surge over the rs485 bus or ethernet (for those that are hard wired) even with ac surge protection.

 

[TonyR68]

Do you have AC surge protection?

Yes. FirstSurge FS140. Just trying to add to the protection after reading some recent experiences here from @ajw22 and @KevMo. Maybe overly cautious. I don’t see much written up on RS-485 protection, so looking for confirmation or guidance on the best way forward.

 

[ajw22]

Just trying to add to the protection after reading some recent experiences here from @ajw22 and @KevMo. Maybe overly cautious. I don’t see much written up on RS-485 protection, so looking for confirmation or guidance on the best way forward.

I see no indication that RS-485 protection would have prevented my PCB from bricking. There was no damage to the RS-485 comm ports on any devices.

EasyTouch systems clearly take hits to the RS-485 chips. The IntelliCenter boards are redesigned and very different than the EasyTouch. I don’t recall anyone having RS-485 comm blow out on an IntelliCenter. So I suggest you don’t associate EasyTouch problems with the IntelliCenter.

I believe the IntelliCenter may have its own board design weakness around the display, CPU, or memory chips. In a while when @ogdento has a chance to autopsy some dead IntelliCenter boards he has, including mine, we may get some insights.

I see where Pentair is updating the IntelliCenter PCB. My failed board was marked REV A and my replacement board is REV B. I don’t know what was changed and maybe it fixed a weakness, or not.

I am not putting RS-485 protection on my system until I learn more. I think it can be more trouble then it is worth in putting more boxes and wires in the comm path that can create more failures.

 

[mas985]

This is only for the connection from the pump to the controller correct? It seems like the only RS-485 surges can come from one of the two components but only in a failure which would cause a voltage spike. Or is there something else going on (e.g. lightning protection)?

 

[ajw22]

This is only for the connection from the pump to the controller correct? It seems like the only RS-485 surges can come from one of the two components but only in a failure which would cause a voltage spike. Or is there something else going on (e.g. lightning protection)?

I think the concern is lightning protection from the RS-485 wires that are acting like antennas outside the cabinet.

 

[KevMo]

I didn't have any damage to my Raspberry Pi's RS485 setup or the RS485 communication with my 3 Intelliflo3 pumps. Everything is working fine except the heater. I did have it connected via RS485 and defined as a MasterTemp heater. The display does not come on and it will not fire up. I changed it back to use the 24V wires for generic gas heater and it still does not work. A tech should be here to check it out early this week.

 

[TonyR68]

Thanks for the feedback. I had just read of the possibility in the Electrical Surge Protection - Further Reading and did not realize that this might have been more specific to EasyTouch. I will hold off on surge protection for the RS-485 comms. Much appreciated.

Tony

 

[mas985]

I would expect a lightning surge on a short RS-485 cable to have a fairly low probability of damage since lightning strikes have energy concentrated in the lower end of the EM spectrum (see below). This why long overhead power lines and long exposed cable runs are much more vulnerable to indirect lightning EM coupling. Just make sure the cable you are using is well shielded with double shielding preferable.

 

[Ahultin]

Just make sure the cable you are using is well shielded with double shielding preferable.

I don't recall the rs485 cables for the pump or intellivalves being shielded, are they? I'm pretty sure the rs485 to the mastertemp used a piece of unshielded cat6 cable (not that we get much lightning in So-Cal)

 

[mas985]

I can't say what comes with the equipment but for areas that get substantial lightning, I would use shielded cable. I don't get much lightning either but I still used shielded data cables to avoid interference that can bring down the comm link.