Component degradation post overvoltage 2

[bazzd]

Hi, Wondering if anybody could advise on the actual degradation of electronic components that would be experienced subsequent to an installation being damaged by transient overvoltage.

My specific situation is that of an external CCTV installation with pole mounted cameras. The cameras failed in a lightning storm, but not as a result of a direct hit. Most likely cause is Induced Transient overvoltage.

While security firm can (albeit reluctantly)repair, the cameras, they are advising on the degradation of the constituent electronics represents a real risk of future failure and as such want to replace them.

Anybody know of a quantitave method to estimate the effect of the overvoltage? I know there is a method for overtemperature derating, but dont imagine this translates to my situation.

Thanks in advance

Barry

 

[IRstuff]

There is no realistic way to assess the amount of damage, since it's not even clear whether you have any solid data on how much over-voltage there was.

Additionally, it's unlikely that anyone has done any testing w.r.t. over-voltage damage mechanisms. In this case and even in the case of thermal stress, you need to run dozens of parts through a series of tests to determine the degree of acceleration induced by the stress. Since most manufacturers are reluctant to test dozens of parts to destruction, it's unlikely that you even have thermal stress acceleration factors.

I would recommend replacing the camera.

TTFN

 

[jbartos]

Suggestion: The overvoltage stresses insulation. If repeated the insulation deteriorate to a point of the insulation puncture.
Visit

http://www.hut.fi/Yksikot/SJT/Vk-2002.pdf

etc. for more info