Wieland samos - Glossary: Characteristic Safety Values; Safety Value Calculation Conditions and Variants

Glossary
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© 2010 Wieland Electric GmbH | BA000256 | 12/2012 (Rev. I)
Characteristic safety values
In the following, you will find the results of calculations of the MTTFd, PFD and PFH values
of different system configurations. They apply under following conditions:
 Units are permanently in operation: 24 h per day, 365 days per year
 Service life (PFH – applications): 20 years
 Proof test interval (PFD – applications): 1 year
 Average ambient temperature: 40°C
Calculation variants
Base moduleE A
Variant 1:
1. single-channel input - single-channel output
2. single-channel input - dual-channel output
3. dual-channel input - single-channel output
4. dual-channel input - dual-channel output
Base moduleE A
Input
expansion
Base moduleE A
Base module
E
A
Relay output
Relay output
expansion
expansion
Input
expansion
Variant 2:
1. single-channel input - single-channel output
2. single-channel input - dual-channel output
3. dual-channel input - single-channel output
4. dual-channel input - dual-channel output
Variant 3:
1. single-channel input - single-channel output
2. single-channel input - dual-channel output
3. dual-channel input - single-channel output
4. dual-channel input - dual-channel output
Variant 4:
1. single-channel input - single-channel output
2. single-channel input - dual-channel output
3. dual-channel input - single-channel output
4. dual-channel input - dual-channel output