What I got out of this article about First-trip testing is that before you even open the breaker you should hook up your test set. If the breaker opens slower than 60 milliseconds is it considered a fail? You fail this breaker because it wouldn't follow the Arc Flash analysis? Or would you operate it and see if the timing corrects itself to 30-50 milliseconds and it be considered a pass?
http://www.circuitbreakeranalyzer.co...ip-testing.htm
An arc flash analysis assumes that the overcurrent protective device (eg a circuit breaker) will clear the fault within the manufacture's published time-current characteristics. A failed circuit breaker, or even a slowly operating one, will result in higher incident energies requiring larger boundary's than specified or a higher level of PPE than called for on placards.
Traditional maintenance testing of circuit breakers requires the breaker to be opened and removed from the enclosure prior to conducting trip testing, thus when a test is conducted it will not a true "first trip" operating time. First trip testing methods can provide a real-life operating time which can be compared to the assumed opening times used in an arc flash analysis.
It's not unusual for the first trip time of a breaker with 5-10 years of inactivity to be 200-300 milliseconds. After the first trip, it will typically be only 30-50 milliseconds. If the first trip time of your breaker isn't less than 60 milliseconds, you're not properly protected from faults.
Note that arc flash studies are based on the energy let through during an event. Time is proportional to energy; and therefore operating at rated speed is critical for calculations and protective schemes to be correct.
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