Switching bt 2 5500w elements, 30amp circuit

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biertourist

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What are the design options for someone who wants a 5500watt element in their HLT and a separate 5500w element in their Kettle but only has 30 amps of head room?

I've seen:

  • Use a 30amp 2 leg mechanical switch (don't like this option, too much personally)
  • The EBrewSupply 30 amp 2 element PID kit solution (3 way switch, 2 SSRs, 2 contactors)
  • Setup control panel as if you have a single element and just physically unplug the HLT and plug in the Kettle (I'd prefer to have both vessels permanently connected, but this is a really simple options)
  • Is there an option that uses a 3 way switch and a single SSR and contactor?

If you're supporting 2 elements with a single PID, won't switching the temperature sensor mess up the PID's calibration?


Thanks,
Adam
 
I don't see why you would need the contactor. You could use 2 SSRs and a two way switch to select one of the SSRs (on the low voltage side).

How are you driving the SSRs? The PIDs could get confused (integrator wind-up) if they are trying to drive a heating element that is turned off.
 
I don't see why you would need the contactor. You could use 2 SSRs and a two way switch to select one of the SSRs (on the low voltage side).
?? Are contactors not the standard prescription when using SSRs? -The second bit of your recommend assumes that there's a brewery-style 3 way switch that could deal with 30 amps -I haven't found one, which is why I was thinking about going the switch + contactors route (plus this is how the EbrewSupply 30 amp 2 element kit does it).


How are you driving the SSRs? The PIDs could get confused (integrator wind-up) if they are trying to drive a heating element that is turned off.
Good call about the PIDs getting confused if they're trying to drive heating elements that are turned off... I didn't think about that at all. Does this really matter? -The pids don't just have an "off" button on them, do they? -I might have to include 2 more illuminated push button switches for the PIDs, huh?


Adam
 
I mean max you can run, given voltage and wire gauge?
The circuit going to my spa panel is a 4 wire 50 amp electric range outlet but the breaker itself is 40 amp, the GFI breaker in the spa panel is 50 amp; 6 awg wire to the spa breaker panel and 10 awg going to the control panel. All 10 awg wire in the control panel everywhere.

-If that's not the question that you're asking, please ask it again with a bit more detail.
Adam
 
On the first page of this thread you will see a diagram that uses such a switch this is the same diagram that I'm currently using. I believe that the switches part number is at the bottom in the ledger of the diagram.
https://www.homebrewtalk.com/f170/opinions-needed-my-electric-brewery-plans-319852/

This is the switch that's linked to in that diagram: http://www.grainger.com/Grainger/NKK-Toggle-Switch-2TPF8

It's just a metal toggle switch and doesn't look like the rest of the brewery switches that so many of these systems are using. No offense, build whatever you want, but I just don't want everything else to use nice plastic push-button and turn-style switches and then to have a random metal toggle switch thrown in the mix.

This is a metal toggle switch that has 240v 30 amps running through it -something about touching a metal switch while my hands are wet while that switch has that kind of current running through it makes me unsettled.


The rest of the control panel has a common look and way of functioning and then there's just this big brute of a switch thrown in. I'd rather use the ebrewsupply solution with a 3 way 120v plastic switch controlling contactors. It's a personal preference and I understand that.


Adam
 
?? Are contactors not the standard prescription when using SSRs? -The second bit of your recommend assumes that there's a brewery-style 3 way switch that could deal with 30 amps -I haven't found one, which is why I was thinking about going the switch + contactors route (plus this is how the EbrewSupply 30 amp 2 element kit does it).


There seems to be a lot of interlocks on the E-brew schematic. I haven;t looked long enough to figure out their purpose. It looks like the contactors are used to completely shut off all voltage to the 240V sockets. I did not use contactors for my build and I assume that one side of the 240 volt socket is always hot.

Functionally you do not have to use a contractor with an SSR. You can wire one side of the 240V directly to the heating element and the other side of the 240v through the SSR and then to the heating element. Think of the SSR as a 40 amp switch. I was talking about using a low current switch between the low voltage side of the SSRs and the PIDs (the light blue wires in the Ebrew schematic). That way you use the SSRs to handle the high voltage and current, but you control things with low voltage low current switches. The low current switch (you could use a two position DPDT switch) would select which heating element is enabled.
 
This is the switch that's linked to in that diagram: http://www.grainger.com/Grainger/NKK-Toggle-Switch-2TPF8

It's just a metal toggle switch and doesn't look like the rest of the brewery switches that so many of these systems are using. No offense, build whatever you want, but I just don't want everything else to use nice plastic push-button and turn-style switches and then to have a random metal toggle switch thrown in the mix.

This is a metal toggle switch that has 240v 30 amps running through it -something about touching a metal switch while my hands are wet while that switch has that kind of current running through it makes me unsettled.


The rest of the control panel has a common look and way of functioning and then there's just this big brute of a switch thrown in. I'd rather use the ebrewsupply solution with a 3 way 120v plastic switch controlling contactors. It's a personal preference and I understand that.


Adam

I used this boot on my panel to address the functional concerns:
http://www.grainger.com/Grainger/NKK-Toggle-Switch-Boot-2TPX6

As far looks, my directive is always: functional before fashion.
After I decided to use this switch (I liked it's function) and boot I continued with that theme and picked all black components and used a black pelican case. I plan to use black out on all my lit buttons and lights so they appear black when not lit (like on custom car's brake light). I think it looks slick and I'm glad it doesn't look like all the other control panels out there.
I'm not to say you should do anything like that, more in that I understand your concerns on looks. Best of luck with your build.
-n
 
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.
 
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.

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
 
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:

SPDTswitch.JPG
 
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:

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
 
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.
 
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
 
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.
 
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