Electrical/RFI Interference

On two occasions now, I have had some type of electrical interference cause issues with the “one wire” devices attached to my BrewPi.

This morning, I found the controller not showing either the beer temp., the fridge temp., or the ambient temp. The controller had been in this state for over 13 hours with no output to the “one wire” SSR (hot fridge…). I was eventually successful in rebooting the BrewPi and once again “see” the three missing temperatures on the controller. Later this morning I realized that I had used a DeWalt (120 VAC, plug in) hammer drill at about the same time that the “one wire” failed.

On two other occasions I have had the same issues with the one wire devices, both times when using a high frequency arc generator with my DC welder. The 220 VAC welder alone has not caused any issues.

Unfortunately, my brewery also has to serve as a garage and workshop.

Curious about RFI interference with the controller I keyed a 2 watt hand held VHF radio next to the BrewPi with no noticeable effects.

I have not had a chance to discuss this with my electrical guru yet. Is the interference passing through the AC system and DC power supply of the BrewPi or is it more likely to be a form of RFI?

I’m very interested as I have also have some instances where the onewire nodes has failed.

I have one question for you in the unfortunate instance that this happens again:

  • Does the probes start working again if you simply unplug an plug one of the probes. The spark should be able to detect and reconnect to the probes without having to reboot the Spark. If that doesn’t work then something more might be going on.

I think my issue might be related to cabling. Any RJ12 cable I have found close by is usually of the old telephone “quality”. Meaning very thin wires and not much more. I have ordered some of Elco’s hand-made RJ-12 cables which are CAT5e and I hope they will help me:-) The assumption might be that the thin cables works, but have very little extra capacity in case the voltage drops slightly i.e. because your hammer drill probably draws a lot of power when it powers up?

I am seriously no poof for my assumptions but it does seem possible. By the way, if you check the SysError log in the advanced settings you should probably get the exact time the probes disconnects…

I momentarily unplugged and replugged the “beer” temperature probe this morning and the temperature did not recover. This probe plugs into a RJ-12 block mounted in the fridge so the probe can be removed for cleaning. The block could be from China however. The probe is one from BrewPi.

One of the other probes that failed (also a probe from BrewPI) is plugged directly into the “one wire” port of the BrewPi itself. This would eliminate any suspect “one wire” cabling issues.

Espen -

I have a lot of “high draw” electrical equipment in the brewery including an air compressor which draws nearly 15 amps @ 120 VAC starting current. Neither this nor any of the refrigerators in the brewery has caused issues with the BrewPi “one wire” devices.

I have not had any other issues with other power tools either. I do not know how the DeWalt hammer drill “hammers”, but I assume the hammering device is electro magnetic and not mechanical. The other piece of equipment that I have noticed causes “one wire” issues is the high frequency booster for my arc welder. This has caused problems with conventional analog temperature controllers I have used in the past.

This doesn’t sound like your cables are the cause.
I suspect EMI from electrical discharge to be the cause.

I have had the BrewPi Spark tested for CE and it met all required standards. The sensors were only lost with the highest industrial interference level, but recovered automatically.

I’ll look into whether there is a bug in automatic recovery that was introduced after I did these tests.

A possible solution could be an EMI Suppression Filter: https://www.google.nl/search?q=EMI+suppression+filter+cable&tbm=isch

As a follow-up, I have continued to have problems with the “one-wire” buss failing and now I am not certain it was caused by EMI. I finally isolated the problem to one of the temperature sensors. This is a sensor (BrewPI) that I have shortened, and fairly obviously had gotten wet on the RJ-12 connector end. I have a spare temperature element (BrewPi) that I’m going to use. Unfortunately I’m out of the country at the moment and cannot replace it remotely. I did epoxy the RJ-12 wire entry area of the new temperature sensor however to water proof it. I hope that this will not cause problems. I will install the new sensor and configure it when I return home.

Brewing in Houston with our high humidity, the “one-wire” buss and SSR inside the refrigerator are continuously damp.