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Creepage and clearance

vinhl

Hello,

Does anyone have any suggestions on a work-around about implementing creepage rule into a high voltage design?

I looked at the previous entry (over 14 years ago). It was not very explicit. I was hoping someone may have a better suggestion today.

We use allegro and OrCad.

There is a company in Germany that has a "plug-in" of some sort (NEXTRA). It states it is compatible with Cadence. We are looking at it as well. But was hoping we can do without it.

Thanks in advance.

Vinh.

  • We do very high voltage designs and still use a manual method.  I am not aware of a creepage calculator.   Perhaps try drawing a line on a board geometry layer that traces a creepage path and measure it.

    I would *love* to have a built-in method from Cadence!

  • I think the first problem is it has to directly correlate to an industry-recognized safety standard.  These companies want money for their calculations per user. 

    My go-to is CSA 61010-1-12.  For the money, you get about 225 pages and covers safety for measurement/control laboratory equipment.  More detailed and restrictive than UL lab standards.

    Calculations change if conductors are Mains connected or floating/isolated from mains by a transformer.   Ultimately, I can see Cadence not wanting to be liable for it.

    If you know what CSA 60079-11 is about, look me up at CDNLive.  We should get blackout drunk together.

  • Thanks for the reply.

    I don't know of CSA 61010-1-12, but I'm sure someone in my company would know.

  • in reply to RFinley

    Also look at the EN60950 standard.

  • I’ve struggled with this topic. Aren’t Spacing Rules in Allegro effectively creepage rules? They define object spacing on the PCB surfaces. I recognize there are some limitations: i.e. - it's not able to recognize slots or barriers in the calculation (as far as I know), but these would only increase the actual creepage distance, so you should be able to perform a robust verification leaving very little, if any, for manual verification, right?  Keeping in mind that the actual creepage value will always be equal or greater than the defined rule, you should be able to meet your creepage requirements using class-to-class Spacing rules.  What I’m I missing?

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