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IEC 62477 clarification - Temporary overvoltages

Finn Beckitt-Marshall

Hello,

I am wondering whether someone would be able to help clarify the differences between IEC 62477-1:2022 and IEC 62477-2:2018 when it comes to temporary overvoltages at a system voltage of 1000Vac?

From Table 7 of IEC 62477-1:2022, for a system voltage of 1000Vac, the temporary overvoltage is determined at 2.2kVrms, whereas from Table 101 of IEC 62477-2:2018, for a system voltage > 1000Vac, the temporary overvoltage is determined at 3kVrms. I notice that Note 2 of Table 101 of IEC 62477-2:2018 states that a different reference standard has been used, but it would be good to understand why there is the difference. Is it simply a case that because IEC 62477-2 is for higher voltage converters, the insulation etc. should be designed with higher overvoltages in mind, or is it just an ambiguity in the standard?

I am relatively new to this so there may be something I've potentially missed.

Thank you in advance for your help.

Kind regards,

Finn

  • +1

    Hi Finn. I believe it is just for the reasons you stated. IEC 62477-1:2022 specifies a temporary overvoltage of 2.2 kVrms for systems up to 1000 V AC, while IEC 62477-2:2018 specifies 3 kVrms for systems above 1000 V AC. This difference is due to the higher voltage systems needing stronger insulation and protection.

    Andrew

  • 0 in reply to AMK

    Hello Andrew,

    Thanks a lot for your help. I'm currently on the team designing a converter which straddles the 1000Vac range, so I think I would take the worse case value from IEC 62477-2.

    Finn

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