Fried a terminal strip in my E-Herms control box

[Ice9]

Hey everybody,

The last time I brewed on my system I fried the terminal strip that connects the power in to the SSR with a cconnection also going to the e-stop. This was the 5 time I had used the system.
Here's a link my my build thread with schematic.
https://www.homebrewtalk.com/f170/six-string-brewing-co-e-herms-build-337791/#post4202367
And here's a picture of the carnage.

Top left black wire goes to the e-stop, top red wire goes to the SSR and the bottom red wire is from the main power inlet.
I've visually inspected the rest of the system and this is the only area that suffered any damage.
I just need some help in finding where the fault is that May have caused this to happen after 5 batches + the initial testing that I did.

Thanks.


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[P-J]

Did you use the same wire color as illustrated in the wiring diagram?

Also, I do not understand -

terminal strip that connects the power in to the SSR with a connection also going to the E-stop

. There is no connection between the E-Stop and the SSR in the diagram.

P-J

 

[Ice9]

Hi PJ,

I used colored electrical tape where the wire color did not match the diagram.
The e-stop is not connected in between the SSR and anything. It is setup exactly as line 2 is shown in the diagram.
They are all connected to the same terminal block.



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[P-J]

I do not have a clue. Something is wired wrong. Sorry..

 

[Brumateur]

Looks like your spade connectors was loosely crimped . Borrow rachet crimping tool somewhere and redo them.

 

[hunter306]

Agreed that it looks like a poor connection. Did you use the Emergency Stop switch on this brewing occasion?

That looks like an issue where there was enough resistance for the amount of current flowing to destroy the terminal. Is there any reason the output to the SSR is all the way at the bottom? I'd also move that up adjacent to your estop line... no reason to run through the bus bar unnecessarily. Keep it simple.

 

[raouliii]

.... Is there any reason the output to the SSR is all the way at the bottom? I'd also move that up adjacent to your estop line... no reason to run through the bus bar unnecessarily. Keep it simple.

I agree. The connections to incoming power and the SSR should be directly across from one another on the terminal strip. There's no reason to have that current flowing through jumper clips.

I assume the wire is 10 or 12 guage?

 

[Docbruw]

Do you have that 1 amp fuse on the e-stop shown in the schematic? NM I just checked out your build thread and I do see the fuse. Did that fuse blow?

 

[smizak]

Looks like your spade connectors was loosely crimped . Borrow rachet crimping tool somewhere and redo them.

^^^^
This. Then troubleshoot the rest. Never under-estimate the damage a loose connection can cause, especially with any appreciable current. I've seen 1AWG wire burn a foot down from a loose crimp and the fuse was fine. Repetitive current spikes can cause tremendous heat in a conductor and a breaker or fuse may not trip.

 

[raouliii]

I don't believe a loose connection of the e-stop crimp would cause this problem, since it draws no current.

I suspect there was a loose connection of the jumpers/terminal screws. With that configuration, full element current must zig-zag across three jumpers to get to the SSR feed. The jumper under the e-stop connection appears to have gotten the hottest. If it were me, I wouldn't have element current running through any of those jumpers. Wire it such that the in-coming and SSR lines are on the same terminal, opposite sides. Jumper to the e-stop lead.

The other possibility is a high resistance short to the case under the terminal strip, but that should have tripped the GFCI.

 

[muhteeus]

That is some wicked oxidation on that terminal. Is there any way moisture could have made its way in there?

 

[52pickup]

Looking at that image, this is what I see;

-Bottom right terminal got hot enough to blacken the yellow terminal cover
-The first jumper from the burnt terminal looks to have a blue/purple tint from getting hot
-Terminal screw above the burnt terminal is golden in color indicating it also got warm
-Center two segments are obviously burnt crispy
-I'm guessing the white is not corrosion, but rather residue from letting the smoke out

Have you put a screwdriver on any of the screws since it failed? I'd guess you had a less than snug one in there some where, which caused an increased resistance. Increased resistance creates heat, which let the smoke out. Once you let the smoke out, you can't put it back in. At least the terminal block is a cheap piece to replace.

As someone else said, I'd not use jumpers between the main feed and the ssr feed. Put those two directly across from each other, and use a single jumper from the main feed to the e-stop feed, as it would only need to feed power for a fraction of a second at a time.

 

[bajaedition]

Lots of heat, somewhere there is a bad connection, the top left wire is a real sloppy connection, are you sure that it crimped on the wire and not the insulation?

 

[kal]

Heat is created when current flows through an area that is too small to handle the amount of current. This can happen with a loose connection where only a few strands connect, a too small of a wire is used, and even when a larger wire is used but only some strands make contact. Can also happen if a part is undersized (same idea – surface area is too small).

It could also be that you’re actually pulling too much current through things past their ratings.

At the end of the day it's because too much current is flowing through a small area.

99% of the time it's a poor connection somewhere causing to much current to flow through a small area which creates heat.

Kal

 

[Ice9]

Thanks for all of the input guys.
I found a screw that wasn't tightened down on a jumper of the terminal strip that is located on the front panel (for the element selector switch and main power button). And I also found one solder connection on the element switch that I was able to rock loose much to easily.
I reconfigured the wiring on the new terminal strip so that the power in and SSR connections are directly across from each other.
Everything powers up fine, I will put some water in the system and test the elements tomorrow.

The white powder was definitely from letting the magic smoke out. Fortunately it was only terminal strip.
Big lesson learned here, be sure to check, check again and recheck every connection, wire and srew in the system!! We're all dealing with a lot of electricity and this could have turned out much worse...

 

[P-J]

Thanks for all of the input guys.
I found a screw that wasn't tightened down on a jumper of the terminal strip that is located on the front panel (for the element selector switch and main power button). And I also found one solder connection on the element switch that I was able to rock loose much to easily.
I reconfigured the wiring on the new terminal strip so that the power in and SSR connections are directly across from each other.
Everything powers up fine, I will put some water in the system and test the elements tomorrow.

The white powder was definitely from letting the magic smoke out. Fortunately it was only terminal strip.
Big lesson learned here, be sure to check, check again and recheck every connection, wire and srew in the system!! We're all dealing with a lot of electricity and this could have turned out much worse...

Good job on the fixup. Wishing you great success.

Another thought for you. I hope your terminal strip and the connectors that you used are rated for at least 30 amps @ 240V. Something like this:

http://www.mcmaster.com/#7527k84/=ra2k34

P-J

 

[Ice9]

Thanks P-J. The terminal strips are indeed rated for 30 Amps, 300 VAC.


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[The10mmKid]

A couple things I can recommend Ice (and other builders),

1) Change over to Ring Terminals
2) I would place both power & SSR terminals under the same screw. (the bottom terminal is flipped upside down)

Those steel jumpers are horrible conductors

Leave the eStop wire where it is.

'da Kid

P.S. Nice Genie release!
Glad the damage was no worse.