Notes on the Declaration of Conformity MTTF

The information stated in the MTTFD declaration of conformity is given without any guarantee.

Our MTTFD calculation is based on a probabilistic estimate assuming constant component failure rates and does not take environmental factors into account. It only applies if the useage time of the components used is not exceeded. Since we do not know the safety function in the customer application, only general dangerous aspects based on Siemens standard SN 29500 and Parts Count Method


according to EN ISO 13849-1 Section D.1 are taken into account.

The MTTFD calculation includes producer data for special components (e.g. ASICs) and SN 29500 (T=40°C, nominal load) for standard components. Components whose data could only be taken from SN 29500 are treated in accordance with EN ISO 13849-1 Section C.5.1. It is assumed that 50% of failures of electrical components take a dangerous course and 50% take a safe course.

Updates to the SN 29500 outside of the change cycles for our product are not checked. This means that newer and possibly worse component data could be available.

For 2-channel versions, the given value is valid for each single channel separately.