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ISO7741-Q1: Reinforced Insulation Maximum Working Voltage vs Certifications/Norms

Ivan Liu Zhu
Prodigy 140 points
Part Number: ISO7741-Q1
Other Parts Discussed in Thread: ISO7741

Hi, 

I would like to understand better the criteria for selecting an isolating component for reinforced insulation:

If we take the ISO7741-Q1 component, there is a big discrepancy on how much the component can withstand in terms of Maximum Working Voltage (If I understood it is VIOWM parameter):

The overall insulation specifications are specifed for the DIN VDE V 0884-11 standard, which would rate the VIOWM as 1500Vrms:

  • For the automotive market, how can we determine if the component would be valid for e.g. 1000Vrms continous working voltage if there are certifications (e.g. CQC and TUV) that show ratings below that?
  • What are the differences in requirements regarding the different normatives?
  • Does these norms/requirements apply to Transformers as well? 

Thanks

  • 0
    TI__Genius 12965 points

    Hello Ivan,

    Thank you for your question.

    In order for a device to be considered reinforced, the device is required to pass 10kV surge isolation voltage according to the VDE standard. 

    • For the automotive market, how can we determine if the component would be valid for e.g. 1000Vrms continuous working voltage if there are certifications (e.g. CQC and TUV) that show ratings below that?
      • This is dependent on your end equipment standard requirements. Your end equipment standard may have a different definition of reinforced isolation you will have to check your standard to find if the ISO7741 meets your standard's requirements. 
    • What are the differences in requirements regarding the different normative?
      • I believe is already addressed above
    • Do these norms/requirements apply to Transformers as well? 
      • Yes, and the transformer would have to meet your end equipment standard accordingly

    Best,

    Andrew

  • 0 in reply to Andrew Jackiw
    Prodigy 140 points

    Thanks for the quick response, 

    • When I was mentioning the difference between normatives, I was referring to the certifications CQC and VDE e.g. One rates the reinforced insulation as permanent 700Vrms and the other one as 1500Vrms. How can be there so much difference? Is the CQC certification much more sever than the VDE one?
    • By end standard requirements, do you refer to which automotive standards will apply to our product? We are developing Battery Management Systems for High Voltage Batteries. It is unclear to me, since this component e.g. is rated automotive, and VDE seems to be a standard for certification of isolators, but customers normally point to IEC 60664 norm only and there is no test that I can relate between VDE e.g. to IEC 60664 to proof reinforced insulation
  • 0 in reply to Ivan Liu Zhu
    TI__Genius 10005 points

    Hi Ivan,

    • CQC standard is GB 4943.1 which is a equipment-level standard whereas VDE standard is a component-level standard. In the component standard, there are no system or equipment level restrictions. For example, equipment standard such as GB4943.1 rates devices based on altitude up to 5000m, pollution degree, CTI of mold compound, etc. These limitations are either not applicable or the values are different for the component standard. That's why the working voltage can be drastically different. 
    • In order to properly pick the correct device for your application, you need to know which standard you need to comply with and what ratings are required for your system. For example, if you need to comply with IEC 60664-1 and need 1000 Vrms reinforced working voltage, then you can either use DWW package with Creepage of 14.5mm or you can use DW package with 8mm Creepage package but you'll need to do potting of your board to make pollution degree 1. 

    I hope this is clear.

    Thanks,
    Saleem Marwat