Electronics > Beginners
Ceramic capacitor will get damaged if repeatedly overvoltaged by spike?
ocset:
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?
Gyro:
--- Quote from: treez on November 14, 2019, 08:55:23 pm ---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?
--- End quote ---
Yes treez, that's why it has a Maximum 630V voltage rating.
Ever heard of de-rating? ::)
P.S.
--- Quote from: treez on November 14, 2019, 08:55:23 pm ---How long would it be before this capacitor did get damaged, when treated like this?
--- End quote ---
You seriously expect an answer to that one?
ejeffrey:
Maybe? It's only about 10% overvoltage, but it is above the rating.
vk6zgo:
--- Quote from: treez on November 14, 2019, 08:55:23 pm ---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?
--- End quote ---
Probably not.
The "630v" rating is a standard value, so there is a fair chance that the cap is really capable of operating at higher voltages.
In addition, the duty cycle is very low, so again, unlikely to cause damage.
All that said, it is very poor practice, &, no, you can't extrapolate from damage being unlikely in this scenario, to one where the cap is subject to over-voltage either continuously, or intermittently, over much longer time periods (days, weeks, years).
ocset:
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.
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