WHAT IS MTBF?
MTBF is used in calculating
reliability. It is an acronym for mean time between failures (MTBF).
Most manufacturers calculate the
reliability of their systems in the same manner that is prescribed
for military products. The process involves determining the basic
reliability of each component that goes into the system.
The reliability estimate is based on
field experience and accelerated life testing. The stress that is
placed on the device in the application needs to be taken into
consideration.
Once the reliability of each component
is estimated and the total number of each is known, the total system
reliability can be estimated. The overall reliability of a system is
usually expressed as MTBF.
The MTBF is usually expressed in hours,
and specifies the average number of hours that can be expected
between failures in the system. The calculated MTBF is only an
estimate and may not really define the actual reliability of the
product.
The inaccuracies come about due to the
many variables that are hard to determine. Such items as the stress
(peak and average current and voltages, and junction temperatures) on
the devices are often hard to determine accurately.
Other factors associated with the
design are almost impossible to estimate accurately, such as noise
susceptibility, effects of accumulated dust combined with humidity,
and the thoroughness and correctness of the design.
Improper reactions of the system to
faults or disturbances can cause the system to fail, but are not
included in component reliability. Proper maintenance and
installation are also often assumed in MTBF calculations.
In general, calculated MTBFs should be
used as guides when actual field data are not available.
Many factors are involved in making a
product as reliable as possible. These factors include design,
component selection, workmanship, and conservative rating of the
units.
It is very difficult to look at a
product and determine its potential for reliable operation.
Estimating the
relative performance of various
products usually requires sorting through reliability information
from manufacturers.
MTBF is an item that can be considered
in determining the reliability of a power system installation.
No comments:
Post a Comment