Westinghouse 150-DHP-500 Breaker

[Borti]

What is interrupting rating of Westinghouse 150-DHP-500 Breaker?
According to a Westinghouse manual from 1965 the interrupting rating of this breaker is 21 kA @ 13.8 kV and 25 kA at 11.5 kV. The manual does not specify symmetrical or total current rating.
Conrad St. Pierre in his "A Practical Guide to Short Circuit Calculations" lists this breaker as both symmetrical and total rated, and none of these ratings matches the Westinghouse manual ratings. Some other sources match St. Pirre's ratings.

 

[DanDel]

The fault currents you have quoted are based on the 500MVA rating of the C/B(that's what the 500 in 150-DHP-500 is). Just divide the 500MVA by the applied voltage and the square root of 3 and you will arrive at your fault current ratings.
These types of C/Bs sometimes have a 'K' factor which is used for this calculation also.