Myth? SSRs fail in the CLOSED state?

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Walker

I use secondaries. :p
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I can't count the number of times I have seen the warning tossed around that SSRs often fail in the closed state, allowing current to flow unchecked. But, I've never actually seen anyone claim that it has happened to them, even after asking those on this forum if they have seen it happen.

A little voice in the back of my mind was wondering if this was another brewing boogeyman.... one of those things one person said one time, and then it just got repeated by everyone until it just became assumed truth. (like hot side aeration).

Well..... BEHOLD! I have the sinister beast in my possession :

SSR_FAIL.jpg


I was going to brew tonight, and was taking advantage of the luxuries of automated temp control. My water was heating while I was bathing my kids and getting them ready for bed, and I was comfortable in the knowledge that my water would be perfectly heated and waiting for me whenever I eventually made it out to the garage to get rolling.

I happened to peek my head out to look at things and saw that the temp was 4 degrees over my set point and still rising. The PID was not attmepting to drive the heat.

I shut it down and returned to muck with it after the kids were in bed. Sure enough... the SSR is busted. It's passing current through no matter what.
 
Yup. I just ordered two more online.

I have a friend who is slooooooooooooowly building his system and has two of them that he is not yet using, so I might swing by there tomorrow.

"Hey, neighbor, can I borrow a cup of sugar.... and 40A solid state relay?"
 
Wow, I kept reading about this being a posibility but geeesh. Do you have a failsafe built into your system and if not are you going to add one?

Mark
 
Wow, I kept reading about this being a posibility but geeesh. Do you have a failsafe built into your system and if not are you going to add one?

Mark

Yes, I have a failsafe wired up. I use a contactor as the master on/off for my element, and the contactor's control signal passes through a normaly closed "alarm" relay built into my PID. If the temp ever gets over 170*F, that alarm relay opens and the contator will shut off. (I caught the overheating before the failsafe kicked in tonight).

Theoretically, I could still be brewing tonight by flipping the PID into a different mode and using the contactor instead of the SSR for control, but that would be hard on the PID's built in relay and the contactor, so I ain't gonna do it.
 
I had one fail "closed" that is when I added the light and the fan. Same exact ebay model as you are holding.
 
I had one fail "closed" that is when I added the light and the fan. Same exact ebay model as you are holding.

Yeah.... I've been dragging my feet on adding a fan to my panel. I've got two very small fans and intend to add one to blow air in and one to blow air out, but it's a drag to have to gut the system so that I can cut the holes in the thing, so it just hasn't happened yet.

I am considering going out to the garage and doing it tonight, though. :D
 
Yes, I have a failsafe wired up. I use a contactor as the master on/off for my element, and the contactor's control signal passes through a normaly closed "alarm" relay built into my PID. If the temp ever gets over 170*F, that alarm relay opens and the contator will shut off. (I caught the overheating before the failsafe kicked in tonight).

Theoretically, I could still be brewing tonight by flipping the PID into a different mode and using the contactor instead of the SSR for control, but that would be hard on the PID's built in relay and the contactor, so I ain't gonna do it.

That sounds like a good way to do it. Which contactor are you using?
Mark
 
That sounds like a good way to do it. Which contactor are you using?
Mark

Just one I found on ebay for a heck of a deal. 40A load, 120V coil. Got it for like $8 and some change. The brand is Smart Electric.

How much usage did you get out of your failed SSR?

Electric system went live almost a year ago, so maybe a little less than 20 batches. Oh, and a few multi-day sous vide cooking sessions, too.

The SSR was only $8, give or take a dollar, so I definitely got my money's worth out of the thing. It just sucks to have to replace it and have a brew night nipped in the bud.
 
Most myths have some basis on fact somewhere along the line, It's just that sometimes the facts are distorted. I this case I guess it's just pure fact.;):D
 
While I'm not motivated to dig up all the threads, I'm pretty certain we've seen at least 2 or 3 other SSR failures here that already confirmed this "myth".
 
While I'm not motivated to dig up all the threads, I'm pretty certain we've seen at least 2 or 3 other SSR failures here that already confirmed this "myth".

Oh, I'm sure there here. I don't keep up with 100% of the threads. I just hadn't personally seen one before. :D
 
Walker said:
Yeah.... I've been dragging my feet on adding a fan to my panel. I've got two very small fans and intend to add one to blow air in and one to blow air out, but it's a drag to have to gut the system so that I can cut the holes in the thing, so it just hasn't happened yet.

I am considering going out to the garage and doing it tonight, though. :D

Are your heat sinks inside the box? Is that why you are considering a fan? Did you ever notice much heat build up?
 
I only have one SSR, but my heatsink is inside the box, yes. The SSR does get pretty warm during the boil. Not so much during mash since there isn't a lot of heating happening, just the occasional blips to boost as needed to maintain mash temp.

edit: "warm" is not fair. The SSR gets hot. Blowing air is definitely in order, and I was brewing on borrowed time.

I've had these two little CPU fans since the beginning of the whole project. I just got antsy to use the thing once it was functional last year and have been avoiding the installation of the fans since I need to cut a couple more big holes in the thing, and have to remove components to give myself space to do the work.

I don't have the right sized hole saw for the fans right now, but I think I might be making a trip to the hardware store today and will install the fans tonight. I've got the spots marked on the box already and the pilot holes drilled.
 
Walker said:
I only have one SSR, but my heatsink is inside the box, yes. The SSR does get pretty warm during the boil. Not so much during mash since there isn't a lot of heating happening, just the occasional blips to boost as needed to maintain mash temp.

edit: "warm" is not fair. The SSR gets hot. Blowing air is definitely in order, and I was brewing on borrowed time.

I've had these two little CPU fans since the beginning of the whole project. I just got antsy to use the thing once it was functional last year and have been avoiding the installation of the fans since I need to cut a couple more big holes in the thing, and have to remove components to give myself space to do the work.

I don't have the right sized hole saw for the fans right now, but I think I might be making a trip to the hardware store today and will install the fans tonight. I've got the spots marked on the box already and the pilot holes drilled.

Well, nice to know that these things do fail closed. Also it seems that proper cooling is very important and was likely the culprit in your case. Thanks for sharing. I will keep this in mind for my panel upgrade.
 
If you read the literature provided by SSR manufacturers, they tell you to install a hard on/off in the circuit because SSRs fail closed.
You can find "name brand" SSRs on ebay, e.g., crydom, gordos, etc. You can buy them quite reasonably if you are not in a hurry. I keep two spares on hand. I have been brewing with an electric system for 4 years and have had not failures thus far.
 
Well, nice to know that these things do fail closed. Also it seems that proper cooling is very important and was likely the culprit in your case. Thanks for sharing. I will keep this in mind for my panel upgrade.

Good thing you and I had a long conversation last week about heat sinks and why it's where it is, huh? ;)

I'm glad I stopped whining about how much room it took up and just let you do it!

By the way, I love the way it's set up with the "main" off/on.
 
Now you have me worried about my kegerator fed power by an SSR. Hate to have that SSR stuck closed and end up with frozen beer and 4 ruined kegs.
 
Now you have me worried about my kegerator fed power by an SSR. Hate to have that SSR stuck closed and end up with frozen beer and 4 ruined kegs.

I wouldn't sweat it. Your kegerator is pulling a mere fraction of the current electric elements do. The cycle rate is much lower too.
 
If you had both legs of a 220 install switched with SSR's, wouldn't it still function with one failed (closed) SSR? Am I correct that this would be a built in back-up? Then again how do you keep track of your set-up to know that both SSR's are still working?
 
Yooper said:
Good thing you and I had a long conversation last week about heat sinks and why it's where it is, huh? ;)

I'm glad I stopped whining about how much room it took up and just let you do it!
"
By the way, I love the way it's set up with the "main" off/on.

Yooper said:
Worst case you will boil in your hlt. It could boil the element dry though if the ssr was stuck on. The float only interrupts the control to the ssr. The boil switch is similar. It only interrupts ssr control.

The main power switch will kill everything. As long as you keep an eye on things and don't walk away for a few hours, I think you are fine.
 
As long as you keep an eye on things and don't walk away for a few hours, I think you are fine.

That seems to be a recurring thing around here......:drunk:

I guess I wasn't remembering that the float only would interrupt the control to the SSR- but it really doesn't matter. Several things would have to fail for that to even be an issue.

Since the HLT gets the water to strike temps in such a short time now, I have no reason to have it on for hours like I used to. I flipped it on yesterday when I went to crush grain, and I was at temperature by the time I crushed grain and grabbed coffee.

This is off-topic from Walker's point about SSRs, but I wanted to tell you that the auto-tuning worked well. The temperature stayed within a degree or two before turning off/on.

I'm really glad that the heat sink is on the back the way it's set up. My previous CP was the same way, so I guess I didn't really think about it.
 
The big 5500W ULWD elements (Lime-Life or something) can be dry fired and survive I'm told. I have not tried it... I have my SSR mounted with the heatsink out the outside of the control box, seems to never get above warm.
 
If you had both legs of a 220 install switched with SSR's, wouldn't it still function with one failed (closed) SSR? Am I correct that this would be a built in back-up? Then again how do you keep track of your set-up to know that both SSR's are still working?

Yes, it would act as a built in backup, and would let you continue on with your brewday. However, you could have a failed SSR and not know it, as you mentioned. The only way to be sure is to occasionally do a systems check where you take a peek at the LED on each SSR.
 
Yes, it would act as a built in backup, and would let you continue on with your brewday. However, you could have a failed SSR and not know it, as you mentioned. The only way to be sure is to occasionally do a systems check where you take a peek at the LED on each SSR.

The LED on the SSR isn't going to help. That thing is driven by the control signal to the SSR and not by the load current flowing through. The LED on my busted SSR behaves properly and only lights up when the PID or PWM says to.
 
The big 5500W ULWD elements (Lime-Life or something) can be dry fired and survive I'm told. I have not tried it... I have my SSR mounted with the heatsink out the outside of the control box, seems to never get above warm.

I dry fired my 5500W ULWD element once. It's a Camco, but is not one of the ripple shaped ones. It's just long and folded back on itself. It survived, but it STUNK up the garage. There was calcium and residue from brewing on it, and that stuff burned up in an instant and left crusty ash on the element that I had to scrub off.

But.... the element looked better than ever after that. Seriously considering a short dry fire every now and then, like a self-clean on an oven. :D
 
...Seriously considering a short dry fire every now and then, like a self-clean on an oven. :D
You are kidding right? I mean there are alot of people out there that hang on every word you guys say....:D Could be a lot of snap crackle and poppin' going on out there. My buddy told me that he powered up his hot water tank with out water in it and the elements immediately blew out and sounded like a gun shot. or so he says....
 
Yes, I was only joking. I assumed the smiley would convey that fact.

I do NOT endorse dry firing your heater element.
 
oh... for you, reelale, i strongly suggest it. go for it.

disclaimer: i am joking again.

Seriously, I wonder if most of these failures are the result of amp draw on 220 vac elements? Or is it equal opportunity? I only use a 110 vac 1500W in a RIMS tube. I'm scared now. I have the alarm working to de-activate the signal on overshoots, but that doesn't do any good when the SSR is not answering the phone.
 
Reelale said:
Seriously, I wonder if most of these failures are the result of amp draw on 220 vac elements? Or is it equal opportunity? I only use a 110 vac 1500W in a RIMS tube. I'm scared now. I have the alarm working to de-activate the signal on overshoots, but that doesn't do any good when the SSR is not answering the phone.

Good thing we are not building nuclear weapons;)
 
Oh you installed those all wrong. It's going to break as soon as you try to brew on it. :D Do you have a picture of the entire CP internals?
 
Oh you installed those all wrong. It's going to break as soon as you try to brew on it. :D Do you have a picture of the entire CP internals?

I don't have one with all the latest additions that I did to it. Will snap one later. It ain't pretty. :D

I recently added a float switch to my kettle to cut the SSR control signal when the liquid level is too low, a toggle to bypass the float (that's part of some future plans I have for this thing), and now these fans. I haven't completed the wiring on the fans because they need as 12VDC power supply. I tested that they worked with a wall-wort, and now the plans are to install that wall wort inside of the panel.
 
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