jCOSbrew

Recipes 

You could also use a single contactor to enable/disable 220v power via a 3-position rotary (or toggle) switch. If you use 2 sets of Normally Open contacts, one set could enable/disable the contactor coil and the 2nd set could connect the PID SSR output to element #1 or element #2. You would still need 2 SSRs.

biertourist

Recipes 

I'm trying to do the electrical mental gymnastics that PJ talks about but I haven't had much gymnastics training so it's just not happening for me...

Have even a rudimentary drawing about what you're talking about because I just can't picture it (and if I am picturing it correctly I don't have enough confidence in my own understanding of this area to feel like I'm picturing it correctly)...


Adam

jCOSbrew

Recipes 

If you use a single contactor then the switch would enable the single contactor in both positions. The second set of terminal blocks could route the PID signal to SSR #1 or SSR #2 in a similar manor.

Electrically these are the same, just a different form factor of switch:

biertourist

Recipes 

I don't understand your insistence that 2 SSRs and heatsinks are required to support a 2 element "switched' 30 amp system.

Won't this work with just a single SSR? (It's hosted directly on PJ's site so I'm assuming it's his and unmodified.)
http://www.pjmuth.org/beerstuff/images/Auberin-wiring1-a4-5500w-30a-e-stop-8a.jpg

Adam

biertourist

Recipes 

Are you saying that if I used these two switches back-to-back that I could get away with a single contactor? (I think I finally understand and that's what you're saying; one switch (the lower amperage one) to control whether the contactor passes power and the other (high amperage toggle-style one) to control to which element the power passes.)

If so, that's a good point and a good design option for someone who's extremely limited on control panel space. (I'm still going to try to squeeze all this into my little box.) -If I have to get rid of something (and I'm pretty sure I don't) I'll get rid of the main power-on switch and contactor and I'll just let the up stream spa panel act as my "main". -The E-stop will turn off power from the control panel, too.


I just placed my full order for all control panel components through Auber so you guys have convinced me to make a 180 degree turn around there.


Adam

biertourist

Recipes 

Unfortunately I'm now poor, fortunately I should be able to make beer again!

jCOSbrew

Recipes 

The picture shows that both form factors of switch are interchangeable, you can use either type within their current ratings, you don't need both. The 3-way rotary switches I used have 10amp contacts, some toggle switches can handle 20-30amps.

If you have a DPDT 3-way switch that can handle the full 30amp load then you can probably get away with a single SSR and a single contactor or no contactor.

Take one of TJ's single element designs and start marking it up.

biertourist

Recipes 

I see what you're saying jCOSbrew and I absolutely agree 100%; I'm glad you spelled it out here for good measure, though. I haven't come across a 3 way rotary switch that could switch the 25amps that I need for my 5500w elements, though. -That's why I see the recommendation by some to use the toggle switch (then you avoid the requirement for a separate contactor(s). I'm just too vein, I guess and I prefer the rotary switch because of how it looks and don't mind trying to cram a contactor into my control panel box.

I WANTED an illuminated 3 way rotary switch but I only found one MFGR and I figured that the wiring would be a bit difficult for me to figure out and I also could save a load on shipping by just buying a non-illuminated switch and keeping the LED indicator lights separate. This also allows me to use 240V LEDs directly tied to the power going to the elements so I have increased confidence on whether power is going to an element or not.


Appreciate all your feedback and taking the time to deal with an electrical newb like me. (Might need help again once I go to wire this thing up...) -How to wire the illuminated switches is still a mystery to me I do have an electrical engineer helping me over Christmas, though.


Adam

jCOSbrew

Recipes 

You can probably find an Allen Bradley rotary switch with 20-30amp contacts for $100, but you can get a Chinese rotary switch for $5 and contactors for $10 each. Also the separate LED indicators are $3 each.

Since my equipment is not in a real industrial environment, seeing 100's of cycles daily, the cheap stuff is good enough for me.