EEVsmoke #2

[bktemp]

Anyone have some good examples of a MOV failure?

Here you go:

What is this device that needs so many MOVs? And what is the black thing with the toriodal core on top of it?

Whenever metal vaporises, it leaves a horrible mess.
That's why you need HRC fuses for multimeters, because cheap glass fuses can explode while trying to interrupt a full mains short.

[Brumby]

Ah!  Found the pics I took of my MOV drama:

The direct view....


From above (with enhancement)


The PCB after cleaning...


The casualties:  (Yes, everything in the yellow frame is was the MOV):

[Brumby]

Dave - I'll send the Hi-Res to you ... in case you are interested.

[amirm]

What is this device that needs so many MOVs? And what is the black thing with the toriodal core on top of it?

It is a service entrance/whole house SPD (surge protection device).  I assumed they paralleled the MOVs to get higher energy absorption capacity.

That's why you need HRC fuses for multimeters, because cheap glass fuses can explode while trying to interrupt a full mains short.

That's right.  Many of these SPDs unfortunately have no fuse so when the MOV goes, it goes really bad.

[Fungus]

Ah!  Found the pics I took of my MOV drama:

Now you know why some people wrap them with heatshrink.... 

[Mike Warren]

From quite a few years ago. The magic smoke had escaped, but it wasn't particularly dramatic. Looks like the mouse could smell fried lizard.

[guido]

There's also magic liquid. One cap turned ballistic and tried to lift off.



Got it working again, it's an off the shelf powersupply in a Kode time interval analyser.

[strawberry]

From some old TV 80's

[iwasz]

Mains went through USB port. Pictured below is an ESD protection IC.

[Nobody2]

From quite a few years ago. The magic smoke had escaped, but it wasn't particularly dramatic. Looks like the mouse could smell fried lizard.

And what's the mouse doing there? Or where both the mouse and the lizard fried? How did they get in there in the first place?!?

[EPTech]

Hi there,

I was repairing a VFD and got another power IGBT module with a blown up brake chopper, massive gate failure. The TVS over the gate and emitter took the over voltage like a boss, shorted out and the mostfet driver seems to have survived thanks to the series resistor to the gate. Although not as impressive as OP picture, The magic smoke got caught in the act. Additionally you can see the bonding wires melted off the emitter, just below the black spot. The intense heat also boiled the gel around the area.

[Mike Warren]

From quite a few years ago. The magic smoke had escaped, but it wasn't particularly dramatic. Looks like the mouse could smell fried lizard.

And what's the mouse doing there? Or where both the mouse and the lizard fried? How did they get in there in the first place?!?

Sorry, I missed this. Both animals had been killed by touching the 240V terminals. My guess is that the mouse smelled fried lizard and went to get some to eat.

[madsbarnkob]

80k views, 5k thumbs, and a normal 5% thumbs down ratio.
So the segment seems very popular.
Although it could still be anomaly because of the awesome captured smoke photo.

I am happy that you like my photo and contribute it some success, it was however sent in by someone that has seen it on my website and did not include proper credits for it.

Please link back to my original article where the photo is from: http://kaizerpowerelectronics.dk/technology/teardown-schneider-electric-frequency-inverter-altivar71/

On your question on how the layers of smoke settled in the gel has happened, it is my thesis that the long and flat flower like black paths in the goo is actually the gasses from the  exploded IGBT die, the gas expands out into the goo that blows a bubble and collapses as soon as the pressure is gone. Leaving a black trail of burned silicon, metal and goo.

[EPTech]

Hi all,

This one reminded me of this topic. Almost a piece of art. Magic smoke flowers. 😁

Greetings and happy tinkering.