Catalogs > Safety Products Catalog > Principles, Standards and Implementation > System Design According to IEC/EN 62061
System Design According to IEC/EN 62061
| System Design According to IEC/EN 62061 |  |
Subsystem Design: IEC/EN 62061 | |
Transition Methodology for Categories | |
IEC/EN 62061 Terminology Overview | |
Diagnostic Coverage (DC) | |
| Management of Functional Safety | |
Probability of Dangerous Failure (PFHD) | |
Proof Test Interval | |
Safe Failure Fraction (SFF) | |
Systematic Failure | |
Automatic diagnostic tests are employed to decrease the probability of dangerous hardware failures. Being able to detect 100% of the dangerous hardware failures would be ideal, but is often very difficult to accomplish.
Diagnostic coverage is the ratio of the detected dangerous failures to all the dangerous failures.
Rate of Detected Dangerous Failures, lDD
DC = -------------------------------------------------------
Rate of Total Dangerous Failures, lDtotal
The value of diagnostic coverage will lie between zero and one.
Hardware Fault Tolerance
Hardware fault tolerance represents the number of faults that can be sustained by a subsystem before it causes a dangerous failure. For example, a hardware fault tolerance of 1 means that 2 faults could cause a loss of the safety related control function but one fault would not.