SSR running hot

[dye4me]

Halfway through my second to last brew I blew a 5500watt element and lost a mechanical relay on the same circuit at the same time. I replaced both on the spot and went about my business and finished the day. Warming up the hot water for my last batch the SSR cooked a post right off. Replaced it and fired things up again and finished the day. Today I went into my controller to screw down the SSR something I just didn't get to on brew day. It was all melted and not looking very good. I did check amp and volt draw after both component replacement, it was normal both time. It was a cool day in the brew room and my large controller cabinate does have a fan and lots of ventilation.

My question is this, did the new SSR melt because it wasn't screwed down and pasted to my heat sink? Did I get two defective relays ( the finest cheapest Chinese type)?or am I casing another gremlin somewhere?

 

[Smellyglove]

What was the rating for the new SSR? Amperage-wise?
How long have you used the setup with the components?
Are your wire gauges as they should?
How are the wires connected to SSR?
Since you blew the 5k5, not dry-boiled?
I'm no electrical engineer, but don't know how you would blow a 5k5 if the resistance is at the SSR, if it IS at the SSR..
Did you measure for shorts? Maybe there's something intermittent. Do you have a GFCI in the panel?

 

[beermanpete]

My question is this, did the new SSR melt because it wasn't screwed down and pasted to my heat sink?

Yes. The SSRs require a heatsink. Use a suitable heatsink compound and bolt the SSRs to a big heatsink. Place the heatsink on the outside of the enclosure if you can with a cut-out in the enclosure for the SSRs so they are inside the cabinet. If you mount the heatsink inside make sure there is adequate air flow through the enclosure via two openings and a fan.

 

[Smellyglove]

Yes. The SSRs require a heatsink. Use a suitable heatsink compound and bolt the SSRs to a big heatsink. Place the heatsink on the outside of the enclosure if you can with a cut-out in the enclosure for the SSRs so they are inside the cabinet. If you mount the heatsink inside make sure there is adequate air flow through the enclosure via two openings and a fan.

It could also be wrong wire gauges, bad connections etc. He hasn't said how big of a SSR he runs either. He said that he cooked a post. Yes SSR's should have adequate means to let heat escape, but it's not 100% that it's due to missing heat sink. But it can be. He also cooked a 5k5 element, which could be due to a shorted SSR though.

 

[beermanpete]

Yes, it could be many things or a combination of things. The SSR should be on a heatsink regardless to improve reliability.

 

[doug293cz]

If a terminal post "melts" on an SSR, or any other component for that matter, it is often because of a loose connection. Bad crimps are included in the loose connection category. Loose connections can have excessive resistance which causes them to over heat with high current flow. If the melting on an SSR is more central, then it's likely the failure is internal to the SSR. As noted previously, not having a properly mounted heatsink for the SSR can cause the SSR to over heat and fail. A shorted SSR should not cause a heating element connected to its rated (or lower) voltage to fail. The element should be able to operate indefinitely at full power as long as it is immersed completely in water or wort.

Brew on

 

[Smellyglove]

That's why I asked all those questions in my first post. We don't know if the element was immersed fully for instance. There's a plethora of reasons it went south both the first and second time.

 

[dye4me]

40amp SSR , all wire gauges are right, checked twice. Crimp connectors put on right with stakon crimpers, I have a heat sink of appropriate size outside cabinate just a PITA to screw SSRs down without removing so I didn't do it. No shorts, GFI in panel, not dry boiled ever. Given the mild plastic Melt I'll grab a new one put it in right and see what happens. Thanks to the great input guys.

 

[Smellyglove]

40amp SSR , all wire gauges are right, checked twice. Crimp connectors put on right with stakon crimpers, I have a heat sink of appropriate size outside cabinate just a PITA to screw SSRs down without removing so I didn't do it. No shorts, GFI in panel, not dry boiled ever. Given the mild plastic Melt I'll grab a new one put it in right and see what happens. Thanks to the great input guys.

With stranded wires it's "easy" to snap a few off without intent. I've seen snapped strands and a good bend on the wire cause stuff to go warm.

 

[Sparkncode]

Yep screws not tightened enough or bad crimp can be a problem. I've seen a bolt and lug in a switchboard at a place I worked glowing red hot.
If you tightened the terminal bolts of the SSR while holding it you might not have got sufficient torque. Much easier to tighten when they are bolted down.

 

[augiedoggy]

not that it would the reason for a screw terminal failure but was the SSR one of those Crappy fake foteks by chance?? there are many of those being sold with internals that only support 10 amps despite different rating stickers being put on them. btw once the wire becomes discolored and oxidized it looses its ability to conduct electricity well and should be replaced.