Damage to offline flyback by hipot test

[Flyback]

Hi,
What kind of damage will be done to an offline flyback during repeated testing at 4kvrms with hipot tester?
The test from L+N to output.

Last sentence of this says hipot testing can damage equipment...

https://tomdunnacademy.org/hipot-testing-101/

"Excessive voltage levels or extended test durations can increase the risk of insulation breakdown, equipment damage, or electrical accidents."

 

[Diver300]

Well any of the isolation components could fail. I would assume that the likely suspects are the transformer insulation, the opto-isolators and any capacitors that connect the HV side to the LV side.

 

[Flyback]

Thanks, do you know the full reason behind the 1mm gap "zigzag" pads which is seen across the isolation transformer?

 

[Diver300]

Thanks, do you know the full reason behind the 1mm gap "zigzag" pads which is seen across the isolation transformer?

That is the spark gap. If the voltage is too large, that is designed to breakdown in a known place, which is better than causing a breakdown in side the isolation transformer.

The problem is that the circuit board can be degraded by the spark. I think it is better to buy a spark gap as a component. Something like this but at a larger voltage:- https://uk.rs-online.com/web/p/switching-spark-gaps/7710026