Lambda V4FFS 12V12A, Руководство по применению

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Vega Customer Applications Manual
Section 7 - MTBF to MIL217F
Rev. A3: October 2003 Page 27 of 48
Section 7 - MTBF to MIL217F
MTBF's have been calculated using MIL-HDBK-217F Ground benign.
The modular nature of the product makes it difficult to determine the MTBF for every combination of output voltages
and load, the numbers given are therefore typical.
The table below gives the failure rate per million hours (FPMH) for each of the assembly types at different ambient
temperatures.
Description 0C 25C 40C 50C
Vega 650W Converter 5.17 7.1 8.72 10
Vega 450W Converter 5.17 7.1 8.72 10
Any module starting with B (Std single) 1.19 1.51 1.82 2.13
Any module starting with C (HC single) 1.23 1.57 1.91 2.25
Any module starting with D (one and a half slot) 1.36 1.75 2.14 2.52
Any module starting with E (dual slot) 1.36 1.75 2.14 2.52
Any module starting with H (twin) 1.88 2.34 2.8 3.23
Any module starting with L (Single) 1.19 1.51 1.82 2.13
To Calculate the MTBF for a given configuration, sum the FPMH figures for each individual assembly/module to
produce a total FPMH. The MTBF is then simply given by 1/FPMH and is expressed in hours.
Example.
Vega 650 B1L E5H H2/1H MTBF at 40°C.
FPMH 650W converter 8.72
FPMH B module 1.82
FPMH E module 2.14
FPMH H module 2.80
15.48
MTBF = 1/FPMH = 1/15.48 = 0.0646 million hours or 64,600 Hours
NB, the above calculation does not include the cooling fan. MIL217F models the fan as a motor and as such, if
included, the figure generated would dominate the overall MTBF figure.
To include the fan then add the FPMH of the fan to the total FPMH :
At 25C Failure rate = 4.09
At 50C failure rate = 7.51