(b) The reliability of a metal sheet cutter is given by the expression 1-(t/6)3/2, 0stS6 R(t) = t > 6 where t is calendar time measured in years. Annual preventive maintenance restores the system to "as good as new" condition. Compare the mean time to failure of the cutter with and without preventive maintenance. 3) (c) A fleet of helicopters operate in the North Sea all year round. One helicopter system is normally on standby, with failure rate on standby of lo = 35 per million hours of calendar time. The system availability should be 0.99. Assuming that the active repair time of the system is negligible, how frequently should the helicopter be inspected? (d) A hydraulically operated gate valve is made up of the seven components, listed in the following table, along with the unavailability of each component. Estimate the availability of the valve, stating any assumptions made. Gate valve components Сар Piston Unavailability 0.0005 0.0002 Actuator body 0.0005 Stem 0.0016 Spring Seal 0.0020 0.0080 Gate 0.0060

(b) The reliability of a metal sheet cutter is given by the expression 1-(t/6)3/2, 0stS6 R(t) = t > 6 where t is calendar time measured in years. Annual preventive maintenance restores the system to "as good as new" condition. Compare the mean time to failure of the cutter with and without preventive maintenance. 3) (c) A fleet of helicopters operate in the North Sea all year round. One helicopter system is normally on standby, with failure rate on standby of lo = 35 per million hours of calendar time. The system availability should be 0.99. Assuming that the active repair time of the system is negligible, how frequently should the helicopter be inspected? (d) A hydraulically operated gate valve is made up of the seven components, listed in the following table, along with the unavailability of each component. Estimate the availability of the valve, stating any assumptions made. Gate valve components Сар Piston Unavailability 0.0005 0.0002 Actuator body 0.0005 Stem 0.0016 Spring Seal 0.0020 0.0080 Gate 0.0060

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter6: Power Flows

Section: Chapter Questions

Problem 6.27P

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