Operational MTBF.

XBTF

There are two main approaches for MTBF calculation :
- The provisional approach consists in evaluating the MTBF on the basis of the failure rate of all components used in the product.
Regarding XBTF PRODUCTS, it seems we have problems to get accurate figures from screen and backlight suppliers.
Moreover, these figures are always very pessimistic (see 22,000 h for XBTF)

- The operational approach is based on the actual product failures, based on the number of returned PRODUCTS.
This approach is accurate only if the PRODUCTS are used by a reasonable amount of customers and for a reasonable period of time.
This is now the case for XBTF PRODUCTS.
This approach is used by Schneider Automation France for Premium PLCs .
Here are the results, based on the period from June 2000 to June 2001 with 385 working hours per month
Part Number operational MTBF
XBTF01 230,000 h
XBTF023 190,000 h
XBTF024 225,000 h
XBTF032 150,000 h
XBTF034 240,000 h
XBTF average 210,000 h