Post Number: 378
|Posted on Friday, April 15, 2005 - 03:42 pm: ||
I'm moving forward with my revamped plans for electric brewing. I have a 5500W element (stainless steel according to the package, not sure what grade) and I just got an order worth of stuff from Allied Electronics, including a Crydom RPC-2440 proportional controller.
In a previous thread I had about this topic, Zymie pitched the idea of using the RPC for control instead of having a traditional 555-based controller built. The RPC line from Crydom just needs a 1/2W 1M ohm potentiometer to control the load, and everything else is contained in the little package.
The device is really slick, but before I get wiring I want to get a second (or more) pair of eyes on the diagram for the Crydom controller to make sure I am interpretting it right. It's pretty basic, I just want to check.
In the diagram above (from the Crydom spec PDF) I'm assuming that the "resistor" between terminals 1 & 2 is actually the load, and the "signal generator" symbol is representing the voltage source. Anyone care to agree?
If so, that means I'd wire it pretty much like I would expect to. One hot leg of my 240V circuit goes directly to my load, and the other hot leg goes through the terminals of the controller, to the load.
Am I on the right track here? It makes sense to me, but I'd like to make sure it makes sense to someone else!
BTW, I plan on fully documenting this project for others to learn about my experiences. The controller was about $100 from Allied and will (hopefully) provide a simple dial-control for modulating power output from ~10-100%, for those curious.
NAYYY with all products/companies mentioned.
Post Number: 102
|Posted on Friday, April 15, 2005 - 07:53 pm: ||
Yep, that appears right. A disconnect and gfci would be a good option. How much load is your proportional controller capable of handling? Richard.
Post Number: 479
|Posted on Friday, April 15, 2005 - 08:03 pm: ||
Now that is a cool little controller. I wish I had one instead of a simple relay.
I think your opinion of the wiring diagram is right. Don't forget the switch to break BOTH line voltages. And remember to attach a big heat sink.
Be wary of strong drink. It can make you shoot at tax collectors -- and miss. ~~Robert A. Heinlein: The Notebooks of Lazarus Long
Post Number: 379
|Posted on Friday, April 15, 2005 - 08:44 pm: ||
Thanks for the opinions, guys!
Richard - The controller is rated for 40A @ 240. I will be putting a max of 5500W through it, so that's 23A. Plenty of head room. I already have a 30A DPST switch rated from 120-277 VAC to provide a master "on-off" for the system. And I found a 6' 30A L6-30 GFCI cordset with 4-6mA trip to protect myself.
They make these units for everything from 15A 120V up to 40A 480V!
George - See above about a master switch. I'm also going to use a small 240V neon lamp as a pilot light to provide visual indication of the master switch being ON or OFF. As for heat sinking, I got an all-aluminum table-top cabinet to house this stuff and will slather some heat-sink compound right to the bottom plate of the controller and bolt it down! I may also sandwich a homemade sink out of copper or aluminum with some "fingers" between the controller and the aluminum case for additional heat dissipation to air.
I think I've actually got most of my bases covered! I'm excited to get started with this... now I just need a drill bit big enough to get a 1" threaded element through!
Oh, one other quick question for the hard-core electronics heads (i.e., Joe R. or Zymie): The data sheet for the controller says a 1M 1/2W pot should be used for control. I got a 1M 2W pot, just assuming that a beefier pot will be able to tolerate any additional heat. That shouldn't be a problem, right?
Post Number: 380
|Posted on Friday, April 15, 2005 - 08:57 pm: ||
Oh, one other thing I should check... I was just thinking about the DP switch I got. It's this:
It says it's rated 30A 120/277VAC. I originally assumed that meant it was OK at 240VAC as well, but it's probably a good idea to ask. 277 is a common commercial voltage off a 480 3-phase, right? Which makes me think that 277 "looks" a lot like 240 in that there are two hot legs and the voltage is derived from the relative difference between the waves, yes? Is there some reason such a switch would work with 277VAC 3-phase but not with 240VAC single-phase? Any thoughts?
Post Number: 623
|Posted on Saturday, April 16, 2005 - 01:31 am: ||
240V single phase is 2 120 legs out of phase....so you should have no problem. In fact that looks just like the master switch that powers up my 240V 5500W heater.
By the way, I assume the relay just cycles the power on and off rapidly rather than outputting a reduced voltage. Is that correct? Sweet for the boil kettle. Are you using a different control scheme for the HLT? Dial it down (and use an external temperature controller?) and it could even be used for a RIMS heater controller. Very sweet...
Post Number: 381
|Posted on Saturday, April 16, 2005 - 01:22 pm: ||
You assume the same thing I do, Don. The description of the unit on the manufacturer's website says it's "perfect for controlling heaters," so I'm assuming they do it "the right way."
HLT control is still pending, because lately I've been brewing without an HLT! I was playing with a process of essentially doing one huge batch sparge, so after my mash was complete I would add the remainder of my liquor to the mash tun and run it all right back to the boil kettle. Obviously the penalty was low efficiency and limited brew capacity, so I will probably go back to an HLT soon.
In that case, I may actually heat the sparge liquor in the main kettle and pump it over (since I'm going to have plenty of power in the kettle. I will probably then hook up a 2KW 120V element to the HLT (maybe even the heatstick that originated this adventure) just for temperature maintenance. Alternatly I could use heavy duty timers and temp controllers to have the HLT kick on during the night and have nice hot water waiting for me in the morning.
Post Number: 64
|Posted on Sunday, April 17, 2005 - 03:41 am: ||
That switch will not be rated for 240V. 277V is an entirely different animal than 240V 1ph. 277V is derived from one phase of a 480V Wye connected system and a neutral (grounded) conductor. 240V 1PH is 2 current carrying conductors, or 2 circuits in other workds.
You will have a 99.99% probability of nothing going wrong with that switch, but it is probably not designed for multiple circuits.
Keep us updated on the project.
(Message edited by zymie on April 17, 2005)
Post Number: 707
|Posted on Sunday, April 17, 2005 - 07:04 am: ||
Bob, I wouldn't use that switch. You say it's DPST? That's a little wierd - 120-277 swithces are generally for lighting, and are usually single pole. You could just use a two pole breaker rated for switch duty, and you could probably pick that up at Home Depot.