SENSseries LB 480 Level measurement
BERTHOLD TECHNOLOGIES GmbH & Co. KG
1 – 99
Volume 1 7 Functional Safety
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7.5.3.1 Determination of the Failure Rates
The failure rates of the device were determined by an FMEDA
according to IEC61508. The calculations are based on component
failure rates according to SN29500. All numerical values refer to an
average ambient temperature during the operating time of 40° C
(104°F). For higher temperatures, the values should be corrected:
• Continuous operating temperature 50 … 60° C (122...140°F)
by a factor of 1.3
• Continuous operating temperature 60 … 70° C (140...158°F)
by a factor of 2.5
• Continuous operating temperature 70 … 80° C (158...176°F)
by a factor of 4.5
Similar factors apply when frequent temperature fluctuations are
expected.
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