I just completed my truncated build: 2 PIDs, 1 5500W element on a 240V line. I had a couple of questions that I hope members can help with. Even though it wasn't necessary, I used a volt/amp combo meter with an induction ring on the black power-in wire between the receptacle and the relay. The picture shows 119V, 2659W and 22.27A which makes sense for the voltage and the wattage cause it's half of the total, but the amperage makes me wonder. Is this the total amps being drawn for the two hot lines? It can't be pulling 44.54 amps cause my 30A circuit breaker would trip.
My other question is about the heat sink. The box I used is a "Bud Industries NBF-32012 Economy Box ( IP66 of IEC 529 and listed to NEMA 1, 2, 4 and 4x specifications)" and I have the heatsink/SSR sandwiched on a piece of thin steel plate which I JB Weld-ed into the top of the box. I brought the water to 100 degrees and while the SSR remained cool, the heat sink was too hot to touch. Is this normal? I see others here have used plastic boxes, has anyone experienced any melting from conducted heat?
Joined: 12 Dec 2010 Posts: 10209 Location: Ottawa, Canada
Drinking: German Lager, Electric Hop Candy Jr, Scottish 70/-, Cali Common, Maibock, Helles, Russian Imperial Stout, Black Butte Porter
Working on: Weizen
Link Posted: Sun Jul 28, 2019 4:17 pm Post subject:
Welcome to the forum!
Something is wired oddly for your combined meter as you should be showing around 240V (not 119V) and the power should be close to 5500W (not 2656W). Currently is likely correct at 22.27 amps as a 5500W element running at exactly 240V will pull 5500/240 = 22.92 amps. If your voltage is slightly lower than 240V, the amperage will be lower too. I would recheck how you have things wired.
Can you post some pictures of your heat sink and how you've got it mounted and the SSR attached? The SSR should be directly connected to the heat sink. Don't sandwich other metals between, and especially don't use JBWeld between metals as I wouldn't imagine it would have great thermal properties. The bigger the heat sink the cooler things will run to. The heat may be completely normal if it's an undersized heat sink (most sold with SSRs are to keep costs down).
Link Posted: Tue Jul 30, 2019 3:22 pm Post subject:
There was another thread on here where the poster was using the same sort of volt/amp meter with an induction ring instead of measuring the current across a shunt. In that thread, Kal recommended that the ring be used on the black line in between the receptacle and the power relay, which is what I did here as well. I tried to use the ring on both black and red hot lines, but the readings were crazy, I guess because the black and red lines are out of phase with each other.
I brewed yesterday and while the heatsink (which uses thermal paste in between the SSR and the thin steel plate and the heatsink and the plate) was quite hot when the element was firing at 100%, during the boil because I'm using a Steam Slayer, I was able to turn the power down to 41% while maintaining a boil and the heatsink cooled off.
I have determined that I can mount the fullsize heatsink from the shop on one side of my case, so I'll be buying one of those.
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