Low/High Frequency Switching Architecture
The information in this section can be used to determine whether you are operating in a low or high frequency architecture.
The electromechanical part of the SIL * starter is characterized with a B10d.
To calculate the MTTFd (according ISO 13849-1) or λd (according to IEC 62061), the following formula applies:
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MTTFd=B10d/(0,1*Nop) with λd=1/MTTFd Nop: Mean number of annual operations |
According to ISO 13849, the operation time of an electromechanical component is limited to T10d (the mean time until 10% of the components fail dangerously*).
Therefore, the operation time of a SIL starter is limited to:
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T10d=B10d/Nop |
The B10d of the SIL starter is B10d = 1,369,863 and assuming a T10d of 10 years, the number of cycles for a TeSys island SIL starter is limited to Nop = B10d/T10 = 131,400/year (or a yearly average of 15 cycles/h).
If the application requires a Nop lower than that value, it falls under the low switching frequency category (where SIL avatars can be used as is). Otherwise, it falls under the high switching frequency category (where the safety function must be implemented with a devoted SIL avatar as described below).