Reliability And Availability - GE Mark VIe System Manual

1.7 Reliability and Availability

1.7.1 Mean Time Between Failure (MTBF)
MTBF is a basic measure of reliability for systems. It is the average failure free operating time, during a particular
measurement period under stated conditions. A failure may or may not result in a problem with the overall system depending
on any redundancy employed. MTBF is usually specified for each replaceable system component.
MTBF roll up of the system components gives the equipment owner the knowledge needed to determine how long the
equipment can be expected to operate without failure under given conditions. If it is essential that the equipment does not fail
during operation, the owner can use this data to schedule maintenance/replacement of the equipment prior to failure.
Alternately, redundant applications could be used preventing system problems when a failure occurs. MTBF data is also used
to determine the weak links in a system. The system engineer provides contingency options for those weak links to obtain
higher reliability.
Users can access the MTBF ratings for their Mark VIeS Safety control system from the Exida, exSilentia tool.
➢ ➢ To access Mark VIeS Safety Controls IEC 61508 certificates and assessment reports
1. Go to the Exida website at
bar.
Type vies in the Search field, and click Submit.
2.
Select the company name, General Electric.
3.
4. At the bottom of the page the user may select to view the following:
• IEC 61508 certificate
• Assessment Report
Note A customer can contact Exida to order a copy of the exSILentia Integrated Safety Lifecycle Tool – Standard version.
All versions of the Exida tool include the SILver module, Safety Integrity Level Verification, IEC 61508 compliant
calculation engine. The SIL verification phase tool, SILver, is an analysis tool that uses Markov model calculation technique
during all analyses. Purchasing the Exida tool gives the user access to the Exida Safety Equipment Reliability Handbook
database.
Control System Overview
and select Safety Automation Equipment List from the top tool
http://www.exida.com/
Public Information
GEH-6721_Vol_I_BP System Guide 49