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How to proove SMPS transformer wont pass EN isolation regulations?

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Advanced Member level 5
Jun 13, 2021
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We have been given a 150W offline SMPS to sample.
Its an "Asymetric Half Bridge with HV auxiliary capacitor instead of dual series capacitor stack" (Single stage PFC)
They want us to buy it.
But i am sure its transformer is just using Litz enamelled copepr wire in both pri and sec, with no margins.

I dont want to expose it to normal hipot test , ie 3500VAC for 1 sec, because that causes slight amount of insulation damage.
What equipment can we choose to proove it wont pass regulations?
Ie, something of a much lower voltage, that has a threshold current limit.
--- Updated ---

Forgot to add, sorry, we are not allowed to smash it apart.
Last edited:

Simply ask your " supplier " to name the safety standards the psu meets, then ( or at the same time ) ask if if meets, 2500 Vac for 1 min pri to sec. Ask if they safety test all units - if yes ask for this in a more formal letter. If they say yes to the 2500Vac - do the test - take it as high as necessary to break it - if it is above 3kV ac - that particular one may be OK.

If it fails below 2500Vac or they don't respond in a satisfactory way - go elsewhere.

Also a simple solution to your odd question is to simply purchase a unit and pull it to bits - after conducting your own tests ...
I don't know if you can -prove- that it -always- will or won't
on an affordable sample size. You can -demonstrate- one
way or the other. You can -demonstrate- small-sample
design margin by running whatever test, by the numbers,
at successive stresses and times.

But destructive phenomena often arise from physical flaws
and then bloom, and the distribution of such defects within
a population is unknown until you do population-level
testing and failure analysis (because besides it failing,
you want to assign the cause and be sure it pertains to
the test you meant to do, and not some mishap or t=0
"should've rejected" defect or inappropriate stress condition.
You can either perform HV tests or analyze clearance and creepage. For a full product qualification, I would do both.
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