New 50 amp, 2 - Element Brew Panel - Questions

[Beernip]

Am in the process of building a new 2 element control panel that models very closely to EBC-350 but with a kill switch. Does anyone have a good wiring diagram for this setup? Going to run a 50A in (6375M) with 2 - L6-30 plugs and 2 - L6-20 plugs out (pumps).
https://www.highgravitybrew.com/store/pc/catalog/Wort-Hog-EBC-350-detail.png

On the the switches. I'm looking at 2 illuminated Auberins SW16 for the elements and 2 Auberins SW15 push buttons for turning on the pumps. I'm not understanding if I need 2NO or 1NO/1NC on these switches?

 

[augiedoggy]

Those switches cant be used to directly turn the elements on and off. unless your just going to use it to double switch the switched pid ssr control output.
To kill all the actual electricity going to the elements you will need to use a dual pole contactor for each element to turn off both hot poles going to the element . For either setup you only need to use 1 NO contact for the switch to activate the contactor (relay) coil..

I dont know how the high gravity panel is built but I doubt theres any contactors in it. They seem to build them as economically as possible vs what they charge. I do know you can get the enclosures they use at the home depot or lowes for $36 and the switches on ebay for about $1.00 each. If they dont use contactors inside to control the outlets, for the $999.00 theres about $260. in material costs besides the vinyl decal. if the do use contactors its about $300 in materials. The explaination from past threads they charge the extra money for the warranty but at those markups you should be able to buy 2 and have a backup ready to go IMO. They can assembly these in under 2 hrs since they do so many..

I would consider shopping around for the generic chinese stuff like the switches and the pt100 rtds... the tri clamp pt100 rtds auberins sells are avaliable for much less with better quality cable here. same deal with the 1/2" npt ones they are from the same manufacturer DTC. (or DTK cant rememeber)
http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=253378587548

 

[Wizard_of_Frobozz]

On the the switches. I'm looking at 2 illuminated Auberins SW16 for the elements and 2 Auberins SW15 push buttons for turning on the pumps. I'm not understanding if I need 2NO or 1NO/1NC on these switches?

It really depends on how you intend to wire up the switches and what you want them to do. NO stands for "Normally Open" and NC stands for "Normally Closed". This means that when the switch is "OFF", the contact is open (for NO) or closed (for NC). Having the extra contact on the switch allows you to hook up indicator lights, or feedback to a controller. Give us some details on what you want the switches to do and we can offer some more detailed advice.

As for the main kill switch, Auber sells some high amperage switches that would work as a kill switch instead of using a contactor. Note that not all of these will work - check the amperage and voltage ratings before you buy. They have to be equal to or larger than your voltage and amperage: https://www.auberins.com/index.php?main_page=index&cPath=69_77

 

[etk29321]

Personally I like the added safety of using contactors just so I know that’s not 50amps flowing through the part I have to touch. Also, electric brewery sells them for $15 ea. That plus a 120v low amperage switch is less than the Auber switch rates for >50A.

 

[Wizard_of_Frobozz]

Personally I like the added safety of using contactors just so I know that’s not 50amps flowing through the part I have to touch. Also, electric brewery sells them for $15 ea. That plus a 120v low amperage switch is less than the Auber switch rates for >50A.

I agree that would be less expensive; just wanted to point out that there are other options if someone wants to do so. Some possible reasons to go with a high amperage switch:
1. A contactor can fail a lot easier than a high amperage switch
2. Less space required in your panel
3. Simpler wiring scheme
4. Having a kill switch that physically interrupts all power into your panel is safer; you know there is nothing hot in the panel if that main switch is open.

I really wouldn't worry about having 50 amps flowing through a physical switch as long as it's rated for it - we have a ton of those in the manufacturing plants where I work and it's 100% safe.

Nothing wrong with the contactor and low amp switch setup - it's safe and works well, but it's not the only way to get it done.

 

[mabrungard]

I disagree with need or desirability of contacts for the system. With the understanding that SSRs do leak current, I employ physical disconnects between the panel and my elements to provide safety and security.

 

[etk29321]

Wait, so are you saying that a contactor is not the same as physically disconnecting? My understanding of a contactor is that when open, they are an open switch no different than a switch you physically flip off.

 

[Wizard_of_Frobozz]

Wait, so are you saying that a contactor is not the same as physically disconnecting? My understanding of a contactor is that when open, they are an open switch no different than a switch you physically flip off.

A contactor (or relay; same thing really) is just a switch that is turned on and off by an electromagnet, so you are correct - you do physically disconnect the lines and it's the same as a switch from an electrical circuit standpoint. For 240vac (in the US anyway), you have two "hot" wires in the circuit, so you need a double pole contactor (or switch...) in order to completely disconnect the power from the load.

The main difference between a switch and a contactor/relay is that the electromagnet is another component that can fail, and if it fails in the closed position, you could have a situation where power is applied and no way to disconnect it. A switch can also fail in the shut position, but it's a lot less likely.

I would say that is a pretty low risk issue, but I do have the ability to physically remove the load from the power source: all of my heating elements are connected to my system via a plug and receptacle. In the event that something really bad happens, I can always unplug them. However, unplugging something when it's under load can lead to arcs that can be dangerous. The safer option is to totally remove power to the rig, so I also have a master off switch that drops power to the entire rig; it's rated for the voltage and current of my system. You could achieve the same thing by running back to your electrical panel and opening the supply breaker. It's all up to you and what you want your system to do. Lots of ways to achieve a safe system.

 

[etk29321]

Totally agree it is another part that can fail. Any part you add to a system is of course.

Fail closed should only happen in the situation where the contacts physically weld together inside the contactor. The contacts are spring loaded such that if there is no power applied to the electromagnet, the contacts will come open under rated loads. If they are welded closed, something bad has probably already happened (e.g. we ran way more current through them than they're rated for). My system is a Kal design, so there are additional fuses that blow at 30A on the output of the contactors to the elements, which should blow long before the 50A rated contactors are over their rated amperage.

Should the impossible happen and they stick closed, you're advice is great about flipping the breaker vs just unplugging things.