ISA Certified Automation Professional (CAP) program

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Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.

CAP question

Consider the following automation system data:

  • Preventive maintenance for 1 hour every month
  • Quarterly preventive maintenance for 2 hours each quarter
  • One failure that results in 6 hours of downtime
  • One failure that results in 4 hours of downtime

What is the uptime for this automation system if it runs 24 hours a day, 365 days a year?

A. 99.66%
B. 99.77%
C. 99.86%
D. 99.89%

CAP Answer

The most important measure for production equipment support is operational availability, or “uptime.”

Automation equipment that operates for 365 days x 24 hours per day = 8,760 total possible “up” hours. This equipment gets preventive maintenance for 1 hour every month (12 hours per year), plus additional quarterly preventive maintenance of another 2 hours each quarter (8 more hours per year).

There was one failure that resulted in 6 hours of downtime and a second failure that resulted in 4 hours of downtime. Thus, total downtime for all maintenance was 12 + 8 + 6 + 4 = 30.

The correct answer is A, “99.66%.”

Reference: Trevathan, Vernon L., A Guide to the Automation Body of Knowledge, Second Edition, ISA, 2006.