Safety-related equipment

Which functional safety values can be adopted to calculate a safety function (with PAScal) for a PT100 sensor? Are there standardised values, for the pneumatic components in the generic database for example?

You can adopt the following values to calculate a safety function in PAScal:

Normative values for automation technology components are listed in Annex C of the standard EN ISO 13849-1. Table C1 deals with components that are subject to wear. The B10d values are stated for the corresponding components, with the exception of hydraulic components.
(The B10d value states the number of cycles until 10% of the components fail to danger.)

Tables C2-C7 deal with electronic components. In this case an MTTFd value is stated. (The MTTFd value is a statistical value, which is determined through endurance tests or reliability predictions based on the probabilities of failure of the components used. It is one element that is taken into account when testing the quality of the components used.)
Temperature sensors are not specified in detail here, however. In accordance with their description, however, we would recommend that you base your system on components whose physical behaviour is the same.

The following generally applies: it is necessary to calculate not just the PT100 but also any evaluation devices or measuring amplifiers that are connected to the PT100.



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