Dum dum question about controlling 220V.

[Charlie]

Hey y'all,

First post, and sorry about the dum-dum question.

I'm building a 15 gallon electric HLT using a decomissioned 1/2 keg, and it will be controlled by my BCS-460. The 3500 watt 220V ultra-low density element will be placed as low as possible on the side of the keg. On to issues...

Looking at Crydom D2440s on eBay I see four contact points. Two are for the controller contacts, and the other two are for the load. How in heck do I switch a pair of 110V legs using two contacts?

Charlie

[RonRock]

Hi Charlie, Interesting "Can-O-Worms" you have opened here, a thread on the very subject you may want to look at.


http://www.homebrewtalk.com/f51/electri ... re-143683/


More than one way to get the job done. I think that the most reasonable (safe, cost effective) way would be to use 2 SSR's for the 220v element.

[ECC]

Yep, RonRock said it. You basically have 3 options:

1. Use a dual SSR. These are basically 2 SSRs integrated into one package for this exact purpose.
2. Use two separate SSR's, one for each leg. A single BCS output can typically drive multiple SSR's.
3. Use a single SSR to switch a single leg of the 220.

For 3), this does break the circuit and the heater will be off (not heat). But it is frowned upon by some because one leg of the 220 is still live at the heater, so it presents a safety concern, code violation, etc etc...

[RonRock]

Somewhat Off Topic, Does it matter how mutiple SSR's are wired together on the Control side?

[ECC]

You will want to control both of the separate SSR's from a single BCS output.

The reason for this is that separate BCS outputs would imply separate independent PIDs, and if they ever got out of sync (not sure how), then you might get one leg on and one leg off, resulting in no heat..

[RonRock]

Thanks, I did not ask my question very well. 2-SSR's controlled by 1 output BCS. Should they be wired in series or parallel?

[ECC]

Thanks, I did not ask my question very well. 2-SSR's controlled by 1 output BCS. Should they be wired in series or parallel?

The SSR's should be wired in parallel.
BCS OUTx ==> Both SSR Control +
BCS GND ==> Both SSR Control -

[Charlie]

Thanks for the replies. I was afraid I was overlooking something obvious. Was not aware of the dual SSRs, but that's a consideration.

While reading the replies it came to me that I could use an inexpensive low amp SSR to control an appropriate 220V relay!

Charlie

[Mark]

Newbie here, another dum dum question reguarding SSR and 220V. If a heating element requires 20 amps (5000w) and you have a SSR on just one leg is it still 20 amps going thru the single SSR? Also I saw a post (somewhere) that you should use a higher rated SSR that actual load. Is that a true statement? I am planning on using 25 amp SSR (crydom D2425) for everything in my system. 3 220v heating elements ( 2 5000w and 1 2000w) and two 110v pumps, do I need more for the 2 5000w heaters?

[BCS Portland]

Newbie here, another dum dum question reguarding SSR and 220V. If a heating element requires 20 amps (5000w) and you have a SSR on just one leg is it still 20 amps going thru the single SSR? Also I saw a post (somewhere) that you should use a higher rated SSR that actual load. Is that a true statement? I am planning on using 25 amp SSR (crydom D2425) for everything in my system. 3 220v heating elements ( 2 5000w and 1 2000w) and two 110v pumps, do I need more for the 2 5000w heaters?

A good way to check amps, etc. = http://www.the12volt.com/ohm/page2.asp