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[Solved] Adding a 3rd element to the schematic

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(@dav4122)
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Joined: 9 months ago
Posts: 10
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So if I want to have a RIMS element as well as the HWT and BK am I relying on the Arduino software to turn SSRs off and on so only 2 can be running at once? and if so I'm just duplicating the schematic for the 2 elements with breaker, coil and SSR to have 3 of these wired appropriately?

Or is there another style of din rail switch/coil that would work similarly to a 3 position dial with RIMS on, off, and BK on? Still controlled by the Arduino I'd guess but slightly less likely to trip a circuit breaker if I program the software incorrectly


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(@pbruno3)
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Joined: 6 years ago
Posts: 333
 

The software and Arduino can drive as many devices as it has outputs for. So for your schematic above, you can add another breaker/contactor/SSR/Element. BUT... you must make sure that only one contactor is on at a time for 30A circuits and two for 50A circuits. You can have a "watchdog" script running in the background that can make sure this is never exceeded, but just in case it happens, your hardware needs to be able to handle the overload so your main breaker trips.


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(@dav4122)
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Joined: 9 months ago
Posts: 10
Topic starter  

Cool so my updated schematic below looks good

The main breaker would go if I had more than two elements on at once

How does this apply to having the larger pump circuits or the 12v power supply also going? Is it more of a "you never run your elements at full strength" or just always having a little extra headroom above what the elements are capable of drawing e.g. although they are on 25A SSRs and 30A circuit breakers they should only draw 20A

 

Just trying to make sure I have a good grasp of the concepts

thanks again


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(@pbruno3)
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Heating elements typically draw ~23 A. That leaves a few amps of headroom for pumps (2 A each).

It's not such a great policy to count on overloading the breaker for safety - it should be last line of defense. But, if you manage your contactors appropriately, then you should be OK.


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