Help - Keep Blowing SSR's

Need a little help here... I recently finished building a small control panel for a 240v 5500w heating element, and I keep blowing the SSR. It seems pretty clear that I have a short somewhere on the system, but I'm not exactly sure where to start with solving this problem.

So, as mentioned I have the control panel and it is pretty simple: a 40amp SSR with heat sink, Auber SYL-2352 PID, and the required 120v and 240v power for each. The power is switched at a separate contactor. Everything tested out ok when I ran a water only test. Then on brew day at one point during the boil my GFCI breaker tripped. When I restored power I discovered my SSR wouldn't work, I could only get full power out of it. So I ordered a couple replacements and put one in, again ran a water test and things worked fine. Then, again during my boil last night the same thing happens. This time I did notice that it was when I went to shift the kettle an inch or two to one side that the GFCI tripped and the SSR blew. So I shut everything down, and as quick as possible replaced the SSR AGAIN, but this third one never worked (I assume the short was there still and it just blew right out of the gate, but the GFCI didn't trip this third time so that's something to consider perhaps).

Clearly there is a problem somewhere, but it is a problem that only kills the SSR and the allows the 240v element to keep plugging away once I restore the GFCI. I'm not sure what causes this. I'm tempted to open up my element connection on the pot to check that, but it just seems that if there was a wiring problem there it would constantly cause my GFCI to trip.

Can anyone walk me through some troubleshooting here? I have a multi-meter, but I'm not sure exactly what to be looking for to find the cause of this.

 

You have a problem either with element or with it connection to cord. Somewhere temporary shortage is happeneng between one of hot leg and a ground. Check your element housing first. Lokks like you havealoose wire. What kind off cord do you use?

 

I'm using a dryer cord. I took my housing apart and took some pictures. Hot leg attachments were solid. Ground appears solid as well, though that connection can be tricky I think with this element housing as the wire is connected to the element housing which spins to connected to the pot.



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Exactly - Check everything down stream of the SSR - also look for chafed cords, etc. Ohm's between either element leg and ground should dang near be infinite.

 

One thought is perhaps some moisture got into the box. Could that cause this type of situation? There was absolutely no evidence of that when I looked this morning. But a little moisture could have dried up in 10 hours.


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Definitely you have to redo an element wiring including a ground wire.

 

It looks like that end cap screws on maybe a half turn or so to lock it in?

If I were in your situation. I would undo the three connections and use some shrink tube over the crimped ends instead of tape. Also when you do the ground connection I would get the wire onto the ground lug and start the nut, then rotate the ground lug 180 degrees so it is away from the 240 volt connections before locking it down.

Once everything is in solid and the end cap is back on. Get into your panel (with everything shut down of course) and check continuity or resistance from each hot leg to ground. You should read OL with a continuity check. If you read anything else you most likely have a short going on somewhere. You could megger the wires also if you have the tools to do so, that will help you ensure your wiring is good, but you have to have all the wiring disconnected before doing so.

With all that said, I'm not sure if its actually the wiring to the element itself anyway. It doesn't really make sense to me that your SSR is just blowing out entirely. I would like to see a pic of your actual control cabinet, and maybe a diagram you used if one exists. Your right that just replacing the SSR is just repeating the problem. I just wouldn't put 100% blame on your element, but check that first just to be sure.

Just one last thought. Due to the expansion and contraction of materials when heated/cooled. When you check continuity from each hot leg to ground, do so with no water, and then dump some boiling water into the pot and heat up the element to see if there are any changes in continuity between the hots and ground. That could be the sneaky culprit.

 

I'll post a picture of the inside of my panel. I'm not sure I can shrink wrap those wires, I don't have a heat gun. These SSR's seem awfully fragile to me. Hard to believe the SSR goes bad if the situation isn't bad enough to keep the element from working.

 

Here's some pics from my panel. Not really complicated. I have 3 wire 240v coming in, one leg of which goes through the SSR before going to the outlet on the left hand side. I have a separate 120v feed coming in to feed the PID and then my control wires from the PID to the SSR.


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Well the box part looks pretty good to me.

A couple points of note. From the 240v feed. You have one wire with a ring terminal going directly to the SSR. Just being nit picky, which I don't intend to be directly, but just a note. I would bend that wire away from the shell of your cabinet.

It looks like your ground from the 240v feed is going directly to the plug for the element. Your 120v feed for you PID has the ground disconnected. The ground between the two are to the same reference, but it would be in your interest to have one of those two wires ground the shell of you cabinet as well.

Technically the ground from the 240v feed would ground your cabinet from the faceplate of the outlet. In my opinion that is not the best reference to ground. It does work though.

One question is how much clearance do you have from the PID to the outlet with the door closed? I assume you have a bit, but if they are close to each other that could cause a problem.

Aside from my being nit picky your cabinet looks good. I would focus on the element side of things first.

 

What size is that element???

I'm using (and it meets NEC code) 12/3 SO cord - much smaller conductors - on my 5500W elements. It's much easier to work with than the 6AWG (I'm guessing) wire you're using.

Have you measured the ohms value from one hot leg of the element to ground? I'm wondering if your element is leaking current to ground.

 

I'll grab my multimeter from work Monday and take some measurements. The element is 5500w and I've used it for about a dozen batches so far.


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Ok, first off, I am no electrician... so please dont take this as gospel.

I ran into problem like this when I was running my office lines a few years back. The project was pretty simple but it got a little hairy when one circuit just wouldnt stay lit for very long. I spent days trying to figure it out and swapped out many expensive parts due to it. then finally said f it - swapped the whole line and it went away. Later when I had more time I knew I have to know so I kept that freaking line and went over it with a fine tooth comb. Never found anything... the morale to my story: sometimes you just cant explain it and it is better to just start over.

For me I went ahah when I saw that you had tripped the breaker as you moved the line a bit. That could be the problem right there. Swap the line and solve the problem imho. Before you do that though - ensure that the fault isnt happening inside the brew hardware unit too - it may just be the angle of the lens but it looks the ground is pretty close to the other connections when you put it back in... random crazy thought.

 

SSR is very sensitive to shortage. If your breaker not fast enough SSR will burn as soon as one leg toched ground.

 

You don't need a heat gun to cause shrink wrap to shrink. Use a match or a lighter. All you need to do is heat the tubing up a bit and it will shrink. Hold it too long on the shrink wrap and it will burn.

 

A hair Dryer may make a good substitute for a heat gun in this case. Worth a try as most households have at least on e hair dryer. S

 

Is that char on your ground wire? You should cut that connection shorter and have the ring terminal facing away from the element power connectors. You would be surprised how well electricity can tunnel the air gap without a spark if the conditions are right.

 

I don't see any char on there, but I will take the advice from so many responses here and clean up these connections and find a way to heat shrink the cables. Might just take this as an opportunity to replace the cable, both to eliminate a possible issue with that cable being bad and also because it has always been something that bothered me: flat dryer cable with round strain relief is just awkward.


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It'd be ok to shorten up that ground wire a bit too. Then it wouldn't have a chance of getting involved with the hot wires or connectors.

 

In my experience, a hair dryer doesn't get hot enough. The last time I tried it, I put masking tape over the air intake to get it hotter (don't try this at home!). I kept adding tape to get it hotter, but the thermal safety switch opened before it ever got hot enough to be useful.

 

I always just use a candle. I've also used my soldering iron.

 

That ground wire/lug is WAY too close to the hot stuff and needs to be moved.

 

You may be using 10/3 wire but that insulation is making this harder than it has to be and appears to be forcing your connectors into places they shouldn't be. To me it looks like, when screwed tight, your element housing is grounding out. You need some 10/3 appliance chord like this. . Notice how small my ring terminals are and how much space your wasting with that big bulky cord.


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Yeah, I've been thinking of upgrading those cords anyways. They were nice from the point of view of being a quick and easy solution, and I never imagined I'd have these type of issues with them. But as they are flat they don't really work well with the round strain relief and are generally a pain to deal with. I'll probably buy new cable and connectors here this week and clean up all of the connections per the advice on this thread. Haven't been able to find my multi-meter at work, so haven't been able to test any of these connections yet.

 

Say, just to wrap up this thread I purchased some new SO cord and re-wired the element using shrink wrap as suggested. Also cleaned up some wiring inside my panel. Have gotten through two successful batches so far. Thanks for the help and suggestions everyone!


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