For relays, what are the values of B10D (number of operations before dangerous failure) and MTTFD (mean time to dangerous failure)?

ID: FAQE10027E



Relays do not have default values for B10D and MTTFD.
For details, see Explanation below.


  • B10D
    Safety components are subject to the number of operations (B10D) before 10% of components reach dangerous failure as specified in International Standard ISO 13849-1.
    Because mechanical relays are used in a variety of applications, we do not evaluate B10D for specific applications.
    Although we do not have the number of operations required to reach dangerous failure (B10D), you can use electrical durability as a reference for B10D.

    B10D = Electrical durability, B10D = 100,000 times (load rating of relay)
    Electrical durability depends on the type of relay and the load rating.
    Refer to the product catalog for details.
  • MTTF
    MTTF (mean time to failure) cannot be set because the time between failure or life differs depending on the load, switching frequency, and operating environment used in the mechanical relay.

Quick tips

In case of dangerous failure specified by ISO 13849-1, the safety component is the target. For relays, refer to “Reliability P level (reference value)” and “Electrical durability.” The same applies to MTBF and FIT.

Product category Relays Signal Relays Power Relays
Classification Selection, Characteristics
Related keywords
  • Signal Relays
  • Power Relays
  • B10D

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