Specification of product reliability

Q. How is the reliability of a product specified?
- Published on 24 Sep 15

a. Always less than 1

b. Always greater than 1

c. Always equal to 1

d. None of the above

ANSWER: Always less than 1

Satyawati Patil -Posted on 07 Oct 15
Reliability is defined as the ability of unit to maintain its quality under the specified conditions for a specified interval of time. It comprises the four major elements such as probability, intended function, time and the operating conditions.

Since the reliability resembles the probability, its numerical value is always specified between 1 & 0. The relationship between the reliability and failure rate of system is expressed by,

R = e^-lt

where, t = operating time & l = failure rate of system

This implies that if the value of operating time is infinity, then the corresponding reliability would be zero.

However, if the value of operating time is zero, then the corresponding reliability would be absolutely '1'. Therefore, the reliability of a system at time t = 0 is 100 %. But, with the practical considerations of failure rate, it is always less than '1'.

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