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Manual 35086
ProTech-GII with Math Functions
Woodward
164
Table 10-3. ProTech-GII SIL3 Numbers:
PFH
7.8E-8 1/h
PFD
PFD
Proof Test Interval
3.7E-5 6
month
5.6E-5 9
month
7.5E-5 1
year
Safe Failure Fraction
SFF > 90%
Diagnostic Coverage
DC > 90%
Failure Rate Data
The Mean Time to Failure (MTTF) is a measure of time between failures that cause a complete process
shutdown. In determining this number, IEC61508 evaluation takes into account safe failure and
dangerous detected failures that cause a module trip.
Table 10-4. Failure Rate
MTTF
> 54 000 years
Because of the nature of the 2oo3 voting structure, a single module trip does not shut down the process.
Response Time Data
The response time for a safety system must be less than the process safety time. The system integrator
must determine the process safety time and the response time of all elements (sensors, ProTech-GII,
actuators, etc.) that make up the total process safety time. For this purpose, the ProTech-GII response
time is given in this manual. Refer to Chapter 3 of this manual and Figures 3-14 to 3-18 for
ProTech-GII-based response time information.
Limitations
When proper installation, maintenance, proof testing, and environmental limitations are observed, the
product life of the ProTech-GII is 20 years.
Management of Functional Safety
The ProTech-GII is intended for use according to the requirements of a safety lifecycle management
process such as IEC61508 or IEC61511. The safety performance numbers in this chapter can be used
for the evaluation of the overall safety lifecycle.
Released
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