SR332 - Telcordia Reliability Prediction Procedure for Electronic Equipment

Introduction 

Reliability prediction is an important element in the process of selecting equipment. This prediction provides necessary input to system-level reliability modes for predicting expected downtime per year and system availability.

SR-332 provides all the tools needed for predicting device and unit hardware reliability. The Telcordia Reliability Prediction Procedure has a long and distinguished history of use within and outside the telecommunications industry. SR-332 provides the only hardware reliability prediction procedure developed from the input and participation of a cross-section of major industrial companies. This lends the procedure and the predictions derived from it a high level of credibility free from the bias of any individual supplier or service provider. 

Definitions 

• FIT (λ): Failure in Time is the rate of random failures, usually expressed in components per giga-hour 
• CL: Confidence level (60% or 90%  is commonly used for the calculation)
• MTTF: Mean Time To Failure 
• MTBF: Mean Time Between Failure 
• MDT: Mean Down Time 
• MUT: Mean Up Time 

Assumptions for calculation 

• The field failures are random failures and can be modeled with the exponential distribution 
• The failure rate (λ) is constant and is expressed in FIT [10-9 h-1]