MC PCB fails in H.V test

[Anil Vaidya]

Hi friends

our MC PCB is failing in H.V test of 1.5 KV / 10 ma for a one minute. we modify clip-page and clearance distance
and found PCB works up to 1.2 KV/10 ma for one minute. Why it fails at 1.5 KV input .
Please suggest.

 

[Genovator]

Maybe the PCB board's fiber plate is acting like a dielectric substance. In RF designs, these fiber boards has significant effect on stray capacitance & antenna matching. One real life example I can share is a tubelight's ballast circuit I had. It often gets short in its 300v(rectified) & 0v trace lines. They are not touching, but are placed much close. But I bought a new ballast of same company, having same circuit design, but still working well. So I concluded its the quality of PCB which could matter. PCBs are mostly made for L.V applications. So maybe not all PCBs can handle such H.V.

 

[bhushan233k]

for 1.5 KV ,10mA how much clearence and creepage u have used?

 

[FvM]

Safety standards require both, sufficient clearance/creepage by design and HV test. Failure in test suggests inappropriate PCB design.

 

[Anil Vaidya]

Yes we check and made the clip page and clearance distance clear. but when we conduct H.V test , MC PCB acts a capacitor i.e. the between earth
and the track dielectric media is there and form the capacitance and when the H.V test is conducted , it gives arcing on the broads and LED dimmed glow

 

[FvM]

What's the actual clearance at the place where arcing occured?