240V 5500W element controller based on Auber SSVR

I want to build a 5500W e-BIAB rig with a controller based on Auber's solid state voltage regulator. This SCR looks similar to the Kyotto unit others are buying on eBay. The only complicating factors are that I'd like to add a main power switch (which I think implies a relay or contactor) and a combination volt/amp meter.

I will have a 240V 30A circuit professionally installed in my garage (with a 30A GFCI breaker in the main panel). I assume it will be a 4-wire circuit, and that I'll use a 4-wire dryer cord to provide power to my controller.

Question 1: Regarding the power switch, is there any benefit to using a 120V switch and a contactor with a 120V coil as opposed to a 240V switch and a 240V coil contactor?

Question 2: The volt/amp meter I found on eBay is rated for 240V, so if I go with a 240V switch/contactor, everything will be wired on 240. I'm wondering what to do with the neutral wire in the 4-wire dryer cord. Can it just be terminated on it's own lug or block in the enclosure, with nothing else connecting to it?

Question 3: Auber's SSVR is rated at 25A; a 5500W element should draw no more than 23A, so I should be "safe", but is there any reason to go with a SSVR rated for higher current? If it matters, the SSVR will be mounted to a great big heat sink salvaged from an old PC.

Thanks in advance for the help.

 

Question 1 - You don't want to use a 120v contactor with your 240v supply - 240v has two hot legs, whereas 120v only has 1 hot leg. You need to switch both hot legs of the 240v to actually turn the panel off, thus you need a 240v rated contactor. The rating of the coil is totally up to you - you can get 120v coils, 240v coils, 12vdc coils - whatever. I'd stick to 120 or 240 - the only impact will be your wiring plan. Note - if you don't care about light up LED buttons and the what not, you can get a 2 pole 240v 30a rated switch and just forego the contactor.

Question 2 - If you're running PURE 240 and don't have a need for 120v, then you can just clip the neutral and leave it off, or go with a 3 wire plug. No need to even get a terminal block to tie it to.

Question 3 - I'm of the opinion that a safety factor in your parts helps them last longer. A 25a SSVR run at 23a will be run at 92% rated capacity whereas a 23a load on a 40a device is only at 58% capacity. To me, this means the parts are less stressed, there will be less heat disipation, and for the relatively miniscule price difference - why not?

-Kevin

 

Thanks, Kevin. I guess my first question wasn't clear - what I was trying to ask is whether there's any benefit, in an otherwise all-240V controller, to running the switch/LED and contactor coil on 120V (with one hot leg and the neutral)? Or can I just keep everything 240V (and use a contactor with a 240V coil)? If I go the "pure 240" route, I'll probably use an Auber SW1 and one of their contactors, if I go with 120V I'd be tempted to use one of their metal SW13's, just to be different.

Regarding the 25A SSVR, yeah, that's pretty much what I figured. I was kind of pumped to see that Auber started carrying them (as they are such a well-respected vendor here), so I just ordered it. If I decide to go with a higher-rated SSVR, I'll have to see about exchanging the one I already have. Ready, fire, aim ...

I just read the 15-page thread in your signature - nicely done.

 

If you have no other reason to run 120v (not running a pump or anything) then don't bother with the neutral and 120v just for a contactor coil. Stick with a 240v coil and 240v switches / LEDs and be happy you did.

I'm sure the 25a SSVR will last fine, just make sure the heat sink is well bedded.

Hahaha, is it up to 15 pages now? I feel like writing about your build is some degree of stress therapy...

-Kevin

 

I used the kyotto ssvr, works great. Much easier to control temps during mash than propane, boil is strong and fast with my 5500w element. As far as neutral, I didn't run one, just the ground. I have a main power switch, a 30a switch from HD. Have any questions about it, just ask.
http://www.homebrewtalk.com/f170/my-planned-ebiab-keggle-cheap-simple-controller-404174/

 

I found this device by asking the sales rep a few questions. Plan on ordering and was hoping someone else might have used previously.

http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=393

 

How tight is the budget? I know a lot of people love the SSVR for how cheap and simple it is, but jumping up to something like the Mypin TD4 (NOT TA4) or even the Auber 2352 with a normal SSR seems like such a no brainer to me. It's like $30 more and you gain temp control rather than a manual power knob. When you're mashing, why chance a temp runaway if you get distracted? Set your controller to 152F or whatever and you're rock solid.

 

Your statement is correct, but I happen to work in the building automation controls field, so I have a programmable logic controller with a PID modulating the VDC signal.

 

Sorry, I was talking to the original poster.

 

I accidentally bought a 240v coil contactor instead of 120v but no big deal. Just jumped one leg of input to one side of coil and interrupt other leg with switch. Works like a charm. I would recommend landing neutral to a terminal bar for ease of future options of adding lights ,alarms, pids and such.

 

Budget really wasn't an issue at all. I'm a big fan of keeping things simple, and wanted to try BIAB. I gathered that in order to use a PID you really need some way to avoid temperature stratification, but recirculating or stirring would add complexity. So a manual temperature control seemed like the way to go, and by and large it has worked out well.

With each new brew I've become more familiar with my rig and am pretty much able to dial it in so the temperature stays within a couple of degrees of my desired mash temp, with only a couple of manual stirs required.