Switchgear MVA and current rating question

[Surefire01]

We have an old Reyrolle S36A circuit breaker which the specs say is rated at 11KV 800A 500MVA. Just doing the math with these numbers they don't seem to add up. From memory VA = Vline x I x root 3. If you put the numbers in it seems like the breaker is rated at: 11000 x 800 x 1.732 = 15.24 MVA and not 500MVA as stated in the specs. Am I missing something?

Cheers

 

[prc]

800A continuous current carrying rating.500 MVA current breaking capacity.

 

[Surefire01]

Of course that would explain it.
Thanks

 

[Zogzog]

It should be pointed out that the constant MVA rating, which was used up until 1999 (Where the switch was made to the current "constant kA ratings were introduced)were intended only as convenient labels, not as an arithmetically accurate calculation of the interrupting MVA for a given rating.

For example, the calculated MVA interrupting capacity for the 350 "MVA class" is typically 338 MVA rather than 350 MVA.