ABB SF6 CB

Can't spot any reason in the manual - maybe it's just a type identifier. Or then again, maybe it means something very significant to Swedish speakers.

What is the IEC standard to which it conforms?.

HPA = Hansa Projekt Anlagentechnik GmbH acquired by ABB in 1996

OK, German speakers.

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This may indicate the wave form of a specific surge voltage, use for surge voltage test. 12 may indicate wave front and 1240 may indicate wave tale.

Are you sure that a CB will be rated in those terms or just guessing ?

Engineering is not a guess-work.

12 - KV rating

12(00) = rated current

40KA = Breaking capacity.

refer IEC 62271 for further.

Yes, I'm guessing. Imagination is the first step of engineering. I'm not guessing about the rating of the breaker. Hi-pot test of breaker can be conducted by two methods. One is applying high voltage at power frequency for 1 min and another is by applying a high voltage surge at surge frequency. This frequency is expressed as 12/500 or 50/1200 us atc. The first no indicates wave front and the 2nd indicated wave tale.