I have a couple of questions, am thinking about building a heat treat oven, firstly what would the amperage need be on the pid, it is turning on and off a pair of 40a ssr's. I see the amperage listed on the aberins as 1 amp at 220 3a at 110 would that be sufficient? I also plan on two elements one each side would they need to be across the back as well? I will be using two elements from texas knifemaker supply site 22 inch for the evenheat oven. unsure yet as to whether will be 220 or 110 I have both voltages available, 30 amp 110 circuit and 50 or 60 amp 220 circuit. recommendations as well as comments are welcome here. been using gas for a while and coal before that neither work well on some of the better steels. now I do mostly carbon and would like to add some of the others.
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couple osf questions about elec. oven
- Thread starter kn4wd
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The PID just sends a low voltage signal to the SSR to turn the coil on and off. It does not handle the actual voltage to the coil. I have a 220V 4000w oven and it runs on a single 220v 30 amp circuit. Remember, with 220v you have 2 hot legs instead of just one, so you don't need to double the breaker size to accommodate it. As for the coils running across the back, I say no. It is where the tips of your blades will be so you don't want a really want a hot zone there anyway. A properly built oven, once it's warmed up, becomes a thermal mass with the bricks keeping the temperature even. Dan Comeau was a big help when I build my oven. Link to his oven build below. There is a very handy excel spreadsheet link at the bottom for figuring out electrical parameters depending on the desired watts, coil wire length, gauge, etc. http://dcknives.blogspot.com/p/electric-forge.html
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The current limits you are quoting appear to be for the alarm relay: plenty to cope with a light or buzzer if you want to use one.
The output to the SSR (s) is shown as 12VDC, 30 mA in the manual. I am not aware of anybody having any problems, but it is worth noting that some SSRs specify a 20 mA input current. If you are feeding 2 SSRs from the SYL2352 output, that could be a 40 mA load.
The easiest way is to feed the (110V) elements in series on the 220V supply. It keeps the current down and gives the SSRs an easier time of it (the heatsink can be a limitation on the switching current long before the maximum rated switching current is reached. It also allows smaller cabling.
The output to the SSR (s) is shown as 12VDC, 30 mA in the manual. I am not aware of anybody having any problems, but it is worth noting that some SSRs specify a 20 mA input current. If you are feeding 2 SSRs from the SYL2352 output, that could be a 40 mA load.
The easiest way is to feed the (110V) elements in series on the 220V supply. It keeps the current down and gives the SSRs an easier time of it (the heatsink can be a limitation on the switching current long before the maximum rated switching current is reached. It also allows smaller cabling.