• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Exposing a ceramic capacitor to repeated overvoltage spikes...causes damage?

Flyback

Well-Known Member
Hi,
I exposed a 630V rated ceramic capacitor (1812, X7R) to a spike voltage of 680Vpk. (the spike voltage as in the attached)
It did not blow up. In spite of the fact that I exposed it to this spike repeatedly, every 4 seconds, over a 5 minute period. Do you think I have damaged this capacitor in any way?
How long would it be before this capacitor did get damaged, when treated like this?
 

Attachments

crutschow

Well-Known Member
Most Helpful Member
How long would it be before this capacitor did get damaged, when treated like this?
There's no way to determine how long a component will last when it used outside its specified ratings.
It could be the next spike or it could operate forever.
 

Flyback

Well-Known Member
Thanks,
I must admit, I once worked in a huge multinational aerospace company. I was doing a board where I needed more capacitance but didn’t have room. We weren’t allowed electrolytics, had to be ceramics. I was publicly trashed in front of the whole office by the Chief Engineer who told me that I should have used ceramic capacitors which were only rated for about half the rail voltage (because they were smaller and I would fit more of them on) …because as he said, ceramic MLCC capacitors can easily withstand this, and he said it was a mark of my ignorance that I was not aware of this.
 

ronsimpson

Well-Known Member
Most Helpful Member
aerospace company
The aerospace company I worked for would remove your cap in post #1 and replace it just because the reliability was the most important thing. Just in case the cap was damaged.
In my experience, the cap is probably OK and is good for consumer products. I would not keep pounding it with over voltage spikes.
(you can measure for leakage, there is a chance a small hole has formed in the insulation)
 

crutschow

Well-Known Member
Most Helpful Member
he said it was a mark of my ignorance that I was not aware of this
No, he's the ignorant one (and apparently also somewhat of a rectum orifice)..
I also worked in Aerospace my whole career, and military reliability requirements are that all parts be significantly derated.
 

simonbramble

Active Member
If it is a ceramic capacitor, I would also be wary of its value changing. It is well documented that a ceramic capacitor's value goes down (drastically) the nearer you get to its working voltage. I would not be surprised if its value also fell through the floor if exposed to multiple voltage strikes above its working voltage. Not sure, but just an educated guess
 

kubeek

Well-Known Member
Most Helpful Member
If it is a ceramic capacitor, I would also be wary of its value changing. It is well documented that a ceramic capacitor's value goes down (drastically) the nearer you get to its working voltage.
But this is because of properties of the dielectric, and I don´t think it is related to electrical overstress. But still the capacity will go down premanently if abused.
 

MrAl

Well-Known Member
Most Helpful Member
Hi,

Something smells fishy here. Or is that a capacitor burning up from over voltage, high frequency AC, or steep rise times?

The fact is that it does not matter what the capacitor is made of. What maters is how the manufacturer rates their components. If they say the voltage is 100 volts and not to go over that, then that's what they mean. If you go over that then you risk product failure at best, possibly a lawsuit.
Ceramic caps are hardy devices but you cant go over the rating. For one thing, if a particular model was made that was found to withstand 150 percent over voltage repeatedly and then the company finds a cheaper way to make the same cap and starts doing that, future end products could start failing on a regular basis.
 

Latest threads

EE World Online Articles

Loading

 
Top