How to measure Reliability?
Consider a single repairable component for which the failure rate and repair rate are constant. The state transition diagram for this component is shown below.
Single component system (a) State space diagram (b) Mean time/ state diagram Let, λ = failure rate of the component µ = repair rate of the component m = mean operation time of the component r = mean repair time of the component. The period T is the system cycle time and is equal to the sum of the mean time to failure (MTTF) and mean time to repair (MTTF). This cycle time is defined as the mean time between failures (MTBF). Sometimes, MTBF is used in place of MTTF.
The following relationships can therefore be defined
m = MTTF = 1 / λ
r = MTTR = 1 / µ
T = MTBF = m+r = 1 / f
Reliability in System Design
The reliability of a device is considered high if it has repeatedly performed its function with success and low if it has tended to fail in repeated trials. The reliability of a system is defined as the probability of performing the intended function over a given period under specified operating conditions.
Important Topics for the Reliability in System Design
- How to achieve high reliability?
- Difference between Reliability and Availability:
- How to measure Reliability?
- What is a Single Point of Failure(SPOF)?
- How to avoid Single point of Failures?