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TOPIC: Electric Element Interlock

Electric Element Interlock 3 years 9 months ago #515

  • Roi.Diver
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Does anyone have any ideas on how to interlock electric elements from firing at the same time, whether in the On or Auto mode?

I've built a 30 amp rated controller using "On/Off/Auto" selector switches, connected to a single RGBIO8 board, supported by an I2C interface. Maybe this is possible in the IDE, I couldn't tell you. I'm more of a hard wire type of guy, trying to figure out the code as I go.
Currently, two control relays are used to mechanically interlock the electric element contactors from firing at the same time. Originally, my thoughts were to energize the control relay coils by using a PV Output per coil, with the "heat" valve profiles. Not sure if it would even be possible, and it isn't a very economical means of using PV Outputs, but it could be added insurance that I don't accidently fire two elements at the same time.
Any thoughts?

Thanks,
Roi.Diver
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Electric Element Interlock 3 years 9 months ago #516

  • jvetter
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Unfortunately, there currently is no way to prevent two elements from running at the same in the current release. In the past I have done something similar, sending the control lines for the SSR into a standard relay to give one element priority over another. That really is your best bet for now and more reliable than software.

That being said, I have implemented a element priority feature for my system which has four elements where only two can be on at a time. I mention it because it is possible to do in software, we just haven't released it as a BT feature. I can bring up the idea at out next meeting, but can't make any guarantees that it will be available any time soon as a feature.

What exactly are you looking to get from a software solution that your hardware solution doesn't already provide?

Cheers,
Jaime
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Electric Element Interlock 3 years 9 months ago #517

  • Roi.Diver
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Thank you for your response, Jaime.

Interesting use of relays on your SSR control. Are you feeding the SSR control through the dry contacts and firing the coils with PV Outputs?

I wired my SSR control straight to the SSRs' and used 12vdc coil relays fired by outputs to control 120vac through the dry contacts. The 120vac was interlocked between the two control relay's N.O. and N.C. contacts and would fire my 120vac contactor coils. The 120vac contactors basically would control the 240vac element power to the SSRs, then out to the elements. Does that make sense? Basically, only one element would fire, no matter if the SSRs were receiving simultaneous SSR signal inputs. I built a separate box (satellite box) for the SSR's and associated controls. I didn't want all of that inside the control panel.

An issue I ended up having (and still having) is that for some reason I wasn't able to get any of my Valve Profile addressing to work. So, I went ahead and bypassed all that mess this weekend, and will rely on never switching both elements to manual "On" position. The PID worked flawlessly when I tested it on the HLT. Of course I'll need to figure out why the valve profile configuration isn't working, but, one issue at a time. I didn't think I had to uncomment anything in the firmware. I guess that was the long winded answer to your question above. lol.

Currently, I'm using v2.5 1026, with Windows. v2.6.6 freezes my displays, even though the one wire temp probes continue to send valid information viewed on the LCD. The displays will boot up, show their addresses, and go blank. I think everything else would work.
Weird, huh?

Thanks again.
Roi.Diver
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Electric Element Interlock 3 years 5 months ago #603

  • katic003
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I had (In a past BT life) posted BT 3.1 b308 power sharing software so only one element is on at a time. The second element would come during the off time of the primary element.
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