Brewery Controller (safety upgrade)
So we had a fire.. Quite shocking (in all aspects of the word). What had happen was the SSR for the boil element melted and caused a short. In short, lots of sparks, flames and smoke!
Since the CraftBeerPi community has grown to become quite substantial, we thought we would share our experience on the CraftBeerPi User Group.
This was both to show other users what happened, the root cause of the issue and possibly avoid more of these incidents in the future. The root cause being one of the 240V connectors had worked its way loose, and didn’t contact fully with the terminal on the SSR causing heat to buildup and finally melt and short.
The SSR in question was a FOTEK 40A SSR, which has been the topic of several discussions over the last years. Most concerns with this brand of SSR is the market being flooded with “fake” versions of it, built with cheeper components and more likely to fail. When we built the first version of the controller, we used the “Mager 40A” SSR. These have worked without any issues since we bought them and has now replaced the two “Fotek” ones for our HLT and Boil elements.
Another thing we picked up from the CraftBeerPi User Group was the idea that 3.3V is potentially a bit low to ensure the SSR is fully open/closed, and with anything that isn’t connected fully, it could raise the resistance in the SSR and in turn generate excessive heat.
So we have now made a Tier 1 switch panel that will run 5V to the SSR. We used a 4x Arduino Relay Module from Wellerman and supply 5V “Common” pin from a 5V power supply.
So now we have ensured that each actor will get 5V. The last two relays runs the water pump and wort pump directly since they dont actually draw that much current and the 10A relays will work just fine.
Next we had to sort the safety out. The thing that concerned us the most, was the fact that it was violently shorting for some time before we had to disconnect the main power cable. Ideally, we should have built the controller with fuses that would cut the power to the SSR as soon as something shorted. So we have now installed 1 fuse before each SSR to add that extra layer of safety.
And when everything is connected back together with some added cable management, it should now be ready for many more years of brewing!
Please let us know if there are questions of something you need a detailed breakdown of, we would be happy to help!