In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
Functional safety means the…
In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
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In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
SIF – Safety Instrumented Function…
In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
A SIS – Safety Instrumented…
A Safety Function is the action of a collection of equipment to implement automatic mitigation of a particular hazard. It is the job of the Safety Instrumented Function (SIF).
Some examples of common Safety Functions:
In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
IEC 61508: 2010 International Performance-Based Standard
The
The IEC 61508 standard recommends the use of a functional safety lifecycle. Any safety lifecycle can be used, but the standard does lay out a nominal 16-step process which can be divided into three main classifications as an example.
The Analysis phase of the lifecycle deals with gathering background…
IEC 61511: 2016 Process Industry Sector
IEC 61511 is a technical standard that sets out practices in the engineering of systems that ensure the safety of an industrial process through the use of instrumentation. It entails requirements for users of process control and instrumentation for component / element or sub-system safety.…
The IEC 61511 standard recommends the use of a functional safety lifecycle. Any safety lifecycle can be used, but the standard lays out a process which can be divided into three main classifications as an example.
The lifecycle is set up like this:
IEC 61508 functional safety standard indicates Safety Integrity Levels (SIL) needs to be evaluated by three design barriers:
Systematic Capability is achieved when the equipment…
IEC 61508 and IEC 61511 functional safety standards allow Safety Integrity Levels (SIL) to be used four ways by end users:
IEC 61508 Certification is a Third-Party Validation against the standard’s requirements, comprising of:
To achieve an…
Do you want to know more about IEC 61508 certification, but you’re not sure if you are ready to jump in? Don’t worry, we will make this process as painless as possible.
Here is what to expect:
Systematic Capability is achieved when the equipment used to implement any safety function achieves two goals: the design process has used procedures intended to prevent systematic design errors (fault avoidance) and the design has systematic design control mechanisms such as a diagnostic for incorrect software execution (fault control). The rigor…
Architectural constraints are limitations that are imposed on the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. Architectural constraints are specified (in) according to the required of the subsystem, type of components used, and of the subsystem’s components. (Type A components are simple devices…
PFDavg (the average Probability of Failure on Demand) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFDavg can be determined as an average probability or maximum probability over a time period. IEC 61508 and IEC…
PFH (Probability of dangerous Failure per Hour) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFH can be determined as a probability or maximum probability over a time period of an hour. IEC 61508 and
Route 1H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem.
Route 1H is…
Route 2H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem.
What exactly is Route 2H…
Safe Failure Fraction (SFF) is defined as the ratio of the average rate of safe failures plus dangerous detected failures of the subsystem to the total average failure rate of the subsystem. It is defined for a single channel (no redundancy, 1oo1).
It is a measurement of the likelihood of…
