Maintenance and Reliability (EEEP3203)
Electrical and Electronic Engineering - EEE
Semester: Second Semester
Level: 300
Year: 2019
THE UNIVERSITY OF B AMENDA
COLLEGE OF TECHNOLOGY (COLTECH)
DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING MAINTENANCE AND
RELIABILITY FINAL EXAMINATION (2018/2019)
INSTRUCTIONS:
Time allowed: 1.5hours.
Full marks can be obtained by answering correctly, ALL questions. The mark allocation per question is
indicated for your guidance. You are advised to show all working and to be precise in your
presentation.
1 (a) Define Maintenance and outline the various types of maintenance. (5mks)
(b) Use a sketch graph to illustrate the impact of adopting reliability engineering on the maintenance cost of
company asset. (5mks)
(c) Describe 5 major impacts of poor equipment reliability on company assets. (5mks)
2. (a) Define the following: (i) Reliability (ii) Failure (iii) Availability (iv) Maintainability (v) MTBF
(l0mks)
(b) (i) Suppose a system must operate for a one year mission and the system has a MTTF = 8760 hours. What is
the system reliability? (5mks)
(ii) Five Pump seals were tested and they were found to fail after an average 2257 hours.
Time studies have shown it takes 5.5 hours to diagnose, remove, replace and check out a unit. Assuming
continuous use and an exponential failure rate, what is the
MTBF, the failure rate, the reliability for a mission of
50 hours in length, and the availability? (5mks)
3. (a) Write an expression for Weibull distribution in: (I) 2-parameters (iii) 3-parameters (4mks)
(b) What makes Weibull distribution better than the exponential function? (5mks)
(c) A computer system has an exponential failure time density function given as;
f(t) =
,
,
≥ 0
What is the probability that the system will fail after the warranty (six months or 4380 hours) and before the end
of the first year (one year or 8760 hours)? (5mks)
(d) The failure time of a certain component has a Weibull distribution with = 4, = 2000, and - 1000.
(3-parameter Weibull). Find the reliability of the component and the hazard rate for an operating time of 1500
hours. (5mks)
4. (a) Name the components of Fault Tree Analysis (FTA). (3mks)
(b) Represent the following, systems on a fault tree and write their corresponding probability expressions.
(7mks)
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