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CrabbeMan
01-20-2015, 07:43 PM
Im looking for a place to start for a beefy electic panel to control our 4 heating elements. I have built my 20 gal homebrew system based off of the electricbrewery setup, but my 10bbl system will obviously need bigger parts!I have 240v 3 phase 400amp panel to play with. Will have 4 15k elements that should be pulling around 230amps while all 4 are on. I plan to use pid with ssr, but dont exactly know where to start with that big of contactors? Any advice on panel parts would be appreciated.

Canuckistan
01-21-2015, 01:24 AM
Having 4 elements is a bit of a pain since one phase is going to be drawing a lot more than the others, and if your panel is only 400A you have a problem...

Do some calculation to see if three elements will provide enough heat output.

Eurotherm makes excellent high current SSRs, but the cost is going to be much more than mechanical contactors. For that kind of current get some Allen Bradley contactors off Ebay and try to figure out how you can balance the load.

Chris

scotts
01-21-2015, 07:39 AM
If you use a PID with a short cycle (like 2 seconds) then you don't want contactors, you want SSRs. Contactors have moving parts and have a dramatically shorter lifespan than solid state relays (SSRs). SSRs can have lifespans of tens of millions of cycles while contactors are in the tens of thousands.

You can buy three-phase SSRs, but I found it cheaper to buy single-phase SSRs and heat sinks and use one for each of the three phases, so it would require about 12 30A SSRs for 4 15kw elements.

Each 15kw element should be 3-phase independent of the other elements, so regardless of how many you have plugged in, will use 3-phases equally. I had mine custom fabricated, but each of my 15kw elements consists of 3 5kw elements in a single 3" tri-clamp end cap.

Beluedog
01-21-2015, 09:48 AM
I am guessing your elements are 3 Phase delta. We use 30K in 6bbl BK and Have 15K on all the time and the other on PID for a ROLLING boil. If I were to redo my panel I would use contactor for 1 bank and ssr for the other. You only need to SSR 2 legs of the 3P though. get 40amp ssr's and a BIG heat sink though they will get hot.

scotts
01-21-2015, 10:04 AM
Looking at my notes, yes, 40A SSRs is what we have as well. 30A is about the bare minimum for 15kw, but I've been told you want some extra room when it comes to SSRs.

CrabbeMan
01-23-2015, 08:11 PM
If you use a PID with a short cycle (like 2 seconds) then you don't want contactors, you want SSRs. Contactors have moving parts and have a dramatically shorter lifespan than solid state relays (SSRs). SSRs can have lifespans of tens of millions of cycles while contactors are in the tens of thousands.

You can buy three-phase SSRs, but I found it cheaper to buy single-phase SSRs and heat sinks and use one for each of the three phases, so it would require about 12 30A SSRs for 4 15kw elements.

Each 15kw element should be 3-phase independent of the other elements, so regardless of how many you have plugged in, will use 3-phases equally. I had mine custom fabricated, but each of my 15kw elements consists of 3 5kw elements in a single 3" tri-clamp end cap.

Can you elaborate a little bit on this? My home brew set up has 2 elements. 1 hlt and 1 bk. each with 2 contactors. 1 hlt and 1 bk along with 2 ssr's to support the contactors. My understanding is the SSR keeps the contactor contacts in place, to stop it from slamming on and off all the time.

Are you saying we should have 3 ssr's per heating element? That seems a little excessive to me? But hey i'm here for advice so I'm all ears. My full time job is building automation so I understand low voltage controls, but anything past 120 blows my mind and thats why I'm here. My father-in law is a 20 yr union electrician so we are trying to piece this together and do it right the first time.

scotts
01-26-2015, 06:45 AM
You will still find contactors in use in panels behind switches, for example a master on/off switch to prevent the switch having to carry a high load through it. But the PIDs will be hooked up to SSRs.

And to clarify, if you have three-phase elements, one option is to have one single-phase SSR for each phase (3 SSRs per element). The more conventional option is to use a 3-phase SSR, and then you would just have one SSR per element.

Canuckistan
01-26-2015, 06:00 PM
SSR stands for solid state relay. When temperature controllers are used in pulse mode they provide short "on" pulses near the setpoint to keep the system accurately at the setpoint.

With mechanical contactors, pulsing them on and off once or more per second will wear them out quickly.

SSRs are used to replace mechanical contactors, not with them. Are your elements 3phase or single phase?

CrabbeMan
02-10-2015, 08:35 AM
Ok this is a good start.

So I will need a total of 6- 3 phase 50amp ssr's?
6 -50 amp contactors?

Along with the 2 auber pid controllers? I know about all of the heatsink, switches etc. Just looking at the big stuff for now.

Thank you

beermkr
02-10-2015, 04:57 PM
No contactors at all. Use the SSR's to control each element. I would suggest that your run some/all of your elements on a PWM circuit so you can fine tune your boil. Biggest advantage to SSR's is being able to control all of it with low voltage.

Problem with using a pid to control vs a PWM is that the boild will not be consistent. Use a pid to maintain a specific temp like in a HLT.

CrabbeMan
02-10-2015, 05:10 PM
No contactors at all. Use the SSR's to control each element. I would suggest that your run some/all of your elements on a PWM circuit so you can fine tune your boil. Biggest advantage to SSR's is being able to control all of it with low voltage.

Problem with using a pid to control vs a PWM is that the boild will not be consistent. Use a pid to maintain a specific temp like in a HLT.

I'm very familiar with pwm. I use them in my current job for hvac applications. I work with andover controls but they are very pricey and it wouldn't be suitable for this. Do you have any suggestions for a pwm controller with temperature probes?

beermkr
02-10-2015, 05:23 PM
I built my own when I was running my electric homebrew setup.

22115

In your case you would drive all your ssr's from one control. Depending on how it all worked for you you may find that you can just put a low voltage switch on a couple of the elements and run them at full blast and tune your boil with the remainder.

Also you might want to run a DC-DC SSR on the output just to make sure you dont pull too much current through the control circuit. Use the PWM to switch low voltage DC to the DC-AC SSR's

scotts
02-11-2015, 05:41 AM
A contactor is handy when you're doing "infrequent" switching, such as on a main power switch to the whole control panel. You won't be able to find a switch that's capable of handling 60kw (or it will be expensive and hard to throw), so you put a low voltage switch in front of a contactor that handles the 60kw.

But a contactor has no place in the PID-SSR-heating element circuit.

The Electric Brewery is a great resource for learning about electric-powered breweries. He goes into a lot of detail about a lot of these concepts when building out his homebrew control panel.

http://www.theelectricbrewery.com/

BTW, I've heard that PWMs burn out heating elements. You might want to do your own research, but that's one concern I've heard. SSRs set to a 2-second cycle maintain a pretty even boil IMHO.

augiedoggy
01-31-2018, 07:22 AM
No contactors at all. Use the SSR's to control each element. I would suggest that your run some/all of your elements on a PWM circuit so you can fine tune your boil. Biggest advantage to SSR's is being able to control all of it with low voltage.

Problem with using a pid to control vs a PWM is that the boild will not be consistent. Use a pid to maintain a specific temp like in a HLT.Old post but,
I disagree here. SSRs leak voltage, also when they fail they almost always fail stuck in the "on" position also if you only use single pole ssrs your only killing one leg of the element power... For that reason many panels (most in the home brewing world) use contactors to mechanically and safely disconnect and connect power to the rest of the circuit including the ssr on all legs of power. also depending on how much power one has its easier to wire up relays to only allow certain elements to be on at the same time to prevent overdraw. You can get away without them but they can add an extra layer of safety as well.