Functional safety components
The mission time of functional safety components is 20 years which equals the time during
which failure rates of electronic components remain constant. This applies to the components
of the standard Safe torque off circuit as well as any modules, relays and, typically, any
other components that are part of functional safety circuits.
The expiry of mission time terminates the certification and SIL/PL classification of the safety
function. The following options exist:
• Renewal of the whole drive and all optional functional safety module(s) and components.
• Renewal of the components in the safety function circuit. In practice, this is economical
only with larger drives that have replaceable circuit boards and other components such
as relays.
Note that some of the components may already have been renewed earlier, restarting their
mission time. The remaining mission time of the whole circuit is however determined by its
oldest component.
Contact your local ABB service representative for more information.
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