Creepage

Indoor Application

How much minimum creepage require the 12Kv Epoxy Insulation and how the creepage measure.

The following is a good link. also try a google search of "creepage distance measurement" or similar

http://www.harkis.harting.com/WebHelp/EGds/WebHelp/GBgdsCreepage_and_clearance_distances.htm

http://www.cadfamily.com/Download.asp?ID=290466

If, i know the creepage distance on insulator (ex:200mm). How much dry power frequency voltage withstand in the insulator.

It depends on the type of insulator, its construction and if the voltage is continuous or a short pulse. Exactly what type of insulator or product are you using? Have you looked at the insulator datasheet or on the supplier website as there should be a maximum ac voltage rating listed.

Also see previous threads on CR4 on the subject. Here is just one example thread.

http://cr4.globalspec.com/thread/27362/What-is-Creepage-Distance