For example, in 200 operations per day, the calculation for the contactor's yearly operation will be: 52 weeks x 5 days x 200 = 52,000 operations per year The B10d value published by NOARK for a contactor under load is 4075230. By dividing the yearly operation by the B10d value, the result is 78 years. This corresponds to a High level of MTTFd, according to ISO 13849-1:2015, which is compatible with the desired safety function. CANADIAN AUTOMATION VOLUME 4, ISSUE 2 14