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Qualifying a the insulation level of a transformer


Member level 3
Oct 19, 2009
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we're designing a battery management system that uses TI-BQ796xx family of AFE/transceiver.
The different boards or modules/ICs communicates between them by using a differential bus in daisy-chain mode. The interface is based on a transformer with a cetral tap as follow:

I found two transformers (Bourns SM91509, Wurth 74942300) but no-one could guarantee a basic level of insulation but just a functional one. On PCB side we're designing following the IEC 62368-1 and the creepage on pcb footprint of the transformer seems enought to achieve a basic insulation.
Also the HI-POT test decleared (4300Vdc) seems enought to guarantee an insulation (basic?) of 1000Vdc.
I called the manufacturers of the transformers that confirms the level of insulation is only functional.

What are the requirements to decleare a basic (or reinforced) insulation on transformer?
Are there some test to be performed on transformer or on the system (PCBA) to guarantee some level of insulation? If yes, which are the standard that describes it?

Thank you!
You are right, the test voltages would be sufficient for 1000V basic insulation. Depeding on the implemented safety standard, e.g. IEC 61010 there are requirements for clearance, creepage and solid insulation thickness which have to be fulfilled. Without knowing the internal construction details, it's not possible to recognize the part as safe.

It's even possible that the parts complies with all requirements but haven't been oficially qualified. You should ask the manufacturers about feasibility and coasts for getting the existing parts qualified respectively modified to your requirements.
Thanks FvM,
Without knowing the internal construction details, it's not possible to recognize the part as safe.
so I cannot do anything other than chose an already-qualified transformer in order to qualify my also my board?

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