Abstract
In this paper the operating times of high voltage SF6
live tank circuit breakers are tested using standard timing tests.
The time measurements obtained have proven to be adequate to
the normal distribution. The hypothesis testing methodology is
applied in order to determine the mean difference value between
the tested phase operating times. The results obtained showed
that the time difference between the operating times of the tested
circuit breakers is located between - 0.661 and 0.536 ms, which
indicates that the operating mechanism of the breakers is still
reliable and in good condition.