SIL 2 Power Contactors - Gt-Engineering

Last edit: 03/07/2023

Some manufacturers have power contactors in their range that contain a bit of electronics. That allows the component to be defined as type B. Moreover, an SFF > 90 % is attributer to the contactor, both in High and in Low demand mode of operation.

That means they can be used without redundancy (HFT = 0) and the output subsystem can reach SIL 2.

We recommend that, in case of HFT = 0, the maximum SIL be limited to 1.

The reason is also because, the same component is declared PL c according ISO 13849-1.

That difference (SIl 2 according to IE 62061 and PL c), was made possible with the first edition of IEC 62061; with the second edition that “approach” is not recommended.

The value of Diagnostic

Index

P3: Considerations on the Safe Failure Fraction in High and Low Demand Route 2H Limits od the SFF parameter Failure Rate for Electromechanical Components SIL 2 Power Contactors The value of Diagnostic Conclusions

Core Competencies

Machinery Directive Machinery Safety Process Safety Functional Safety UL and CSA Conformity Electrical Safety and Arc Flash Mitigation ATEX Risk Gas Furnaces - CE Marking

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