[RE-wrenches] MTBF

[Glenn Burt]

All, 

MTBF is and has been a valid measurement in the electric/electronics
manufacturing world for many years, used by all manufacturers. I have not
looked, but I suspect all inverter manufacturers could give an equivalent
number for their products.

It is not something new or whiz-bang.

However it remains a purely theoretical method of quantifying a failure rate
on a product that has few years of 'in-the-field' lifetime to back it up,
and should not be confused with MTTR (mean time to replace), which also is a
valid tool used for many years.

Coming from a manufacturing field, I can verify that it is a time-consuming
calculation with arms reaching into MIL-SPEC as well.

-Glenn Burt  

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Marv Dargatz
Sent: Thursday, March 26, 2009 1:38 PM
To: RE-wrenches
Subject: [RE-wrenches] MTBF

All,

Mean Time Between Failure (MTBF) is a statistical number that is based on
failure rates of components in a piece of equipment, under specific
operating conditions. Numerical analysis, with testing and historical data,
results in this calculated number.  MTBF can be applied to a number of real
world mechanisms.  For example, the MTBF of most solar modules is on the
order of 600 years.  The MTBF of an average American 30-something year old
male is 900 years.  Enphase will shortly be publishing a white paper that
explains how MTBF ratings are determined and gives more details about the
MTBF rating of our micro-inverter.

If you would like, I'll post a notification on this list when the paper is
available.

See Ya!

Marv
Enphase Energy
707 763-4784 x7016

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