It happens. The power company was very unhappy with my boss for destroying one of their transformers. The thing is while circuit breakers react very quickly to extreme overcurrent situations (shorts) they're much slower to react to loads which are only a bit over the limit, and if short enough won't react at all. Very common with heavy motors.
And that's exactly what the problem was--we had a whole bunch of really heavy motors. Getting ready to start for the day you flip on the switches and the big machines start to spin. The transformer on the pole was rated higher than the main breaker for the plant--but the transformer apparently was more sensitive to the temporary loads. Once the problem was identified it was resolved by staging it, instead of flipping them all on they were flipped on over 5 minutes.
And that's exactly what the problem was--we had a whole bunch of really heavy motors. Getting ready to start for the day you flip on the switches and the big machines start to spin. The transformer on the pole was rated higher than the main breaker for the plant--but the transformer apparently was more sensitive to the temporary loads. Once the problem was identified it was resolved by staging it, instead of flipping them all on they were flipped on over 5 minutes.