Topic 2-Reliability and Availability

Question 1

Define what is the capacity factor of a wind turbine.

Answer 1

It is defined as the percentage of the actual annual energy production over the rated annual energy production from a wind turbine or a wind farm.

Question 2

What do MTBF, MTTF and MTTR stand for? How do they relate to the Failure rate and Repair rate?

Answer 2

: MTBF = Mean Time Between Failures; MTTF = Mean Time To Failure; MTTR = Mean Time to
Repair.

Question 3

What is failure rate?

Answer 3

1/MTBF

Question 4

What is repair rate

Answer 4

1/MTTR

Question 5

What is the availability of a wind turbine? How it relates to the failure rate and repair rate?

Answer 5

Availability is the probability of finding a system in the operating state at some time into the
future.

Manufacturers availability = 1-(failure rate/repair rate)
Operators Technical availability < 1-(failure rate/repair rate)

Question 6

What are the means to improve the WT availability?

Answer 6

Increase Availability by reducing the failure rate and time to repair (down time).

Question 7

Sketch the bathtub curve and identify the useful life region.

Answer 7

In lecture slides