Some observations on novel concepts in new IEC 61508 draft

2009 ◽  
Author(s):  
J. Braband ◽  
S. Griebel
Keyword(s):  
Iec 61508

Mathematical Approaches in Functional Safety Assessment for E/E/PE Safety-Related Software

2021 ◽  
pp. 2150043
Author(s):  
Shinji Inoue ◽  
Takaji Fujiwara ◽  
Shigeru Yamada
Keyword(s):  
Software Reliability ◽  
Safety Assessment ◽  
Assessment Method ◽  
Functional Safety ◽  
Reliability Modeling ◽  
Software Failure ◽  
Safety Integrity Level ◽  
Iec 61508 ◽  
Systematic Failure ◽  
Quantitative Safety Assessment

Safety integrity level (SIL)-based functional safety assessment is widely required in designing safety functions and checking their validity of electrical/electronic/programmable electronic (E/E/PE) safety-related systems after being issued IEC 61508 in 2010. For the hardware of E/E/PE safety-related systems, quantitative functional safety assessment based on target failure measures is needed for deciding or allocating the level of SIL. On the other hand, IEC 61508 does not provide any quantitative safety assessment method for allocating SIL for the software of E/E/PE safety-related systems because the software failure is treated as a systematic failure in IEC 61508. We discuss the needfulness of quantitative safety assessment for software of E/E/PE safety-related systems and propose mathematical fundamentals for conducting quantitative SIL-based safety assessment for the software of E/E/PE safety-related systems by applying the notion of software reliability modeling and assessment technologies. We show numerical examples for explaining how to use our approaches.

Achieving ISO 26262 & IEC 61508 objectives with a common development process

2019 ◽  
pp. 247-255
Author(s):  
Gadila Prashanth Reddy ◽  
Rangaiah Leburu ◽  
Kankanal Rajireddy ◽  
P Jayakrishnan ◽  
Justin Khoo
Keyword(s):  
Development Process ◽  
Iso 26262 ◽  
Iec 61508

scholarly journals Improvements in the performance of an SIS by bypass reduction on the safety functions

2020 ◽  
Vol 5 (4) ◽  
pp. 224-231
Author(s):  
Ramdane Sklab ◽  
Youcef ZENNIR ◽  
Riad BENDIB
Keyword(s):  
Significant Period ◽  
Sustainable Exploitation ◽  
Iec 61508 ◽  
Oil Company

In order to maintain the integrity of its installation, the BIR EL MSANA (BMS) oil company has equipped itself with a safety instrumented system (SIS), complying with IEC 61508 and IEC 61511 standards. Whereas some constitutive functions of this system are disabled and not available, this means that the installations remains unprotected for a significant period of time, hence the obligation to look for adequate and permanent solutions. Through this work, we clarify the causes that led to this deactivation, proposing effective solutions for each case, this will allow reactivating them and ensuring a safe and sustainable exploitation.

scholarly journals SIL Implementation on Safety Functions in Mass Transit System

2018 ◽  
Vol 3 (3) ◽  
pp. 258-270
Author(s):  
James Li
Keyword(s):  
Mass Transit ◽  
Control Technology ◽  
Transit System ◽  
Safety Integrity Level ◽  
Iec 61508 ◽  
Safety Function ◽  
Defense Technology ◽  
The World ◽  
World Demand ◽  
En 50129

The concept of Safety Integrity Level (SIL) has been developed within different systems of standards (IEC 61508, EN50129 and DEF-STAN 00-56). These standards are applied in different areas: control technology (IEC 61508), railway technology (EN50128 and EN 50129), and defense technology (DEF-STAN-00-56). Nowadays, a lot of the mass transit turnkey projects around the world demand the contractors to follow CENELEC standards and SIL concept for the safety function implementation. Although the concept of SIL is mentioned in these standards, the interpretation of the concept of SIL in these standards is not consistent and unequivocal. This paper is written to elaborate the anomalies of SIL interpretation among these various standards in order for safety engineers to obtain a more detailed view on the concept of SIL over these standards.

scholarly journals Genetic Algorithm Optimization Model for Determining the Probability of Failure on Demand of the Safety Instrumented System

2019 ◽  
Vol 1 (2) ◽  
Author(s):  
Ahmed H. Aburawwash ◽  
Moustafa Mohammed Eissa ◽  
Azza F. Barakat ◽  
Hossam M. Hafez
Keyword(s):  
Genetic Algorithm ◽  
Accurate Determination ◽  
Probability Of Failure ◽  
System Structure ◽  
Control Element ◽  
Algorithm Optimization ◽  
On Demand ◽  
Uncertainty Sources ◽  
Iec 61508 ◽  
Proposed Model

A more accurate determination for the Probability of Failure on Demand (PFD) of the Safety Instrumented System (SIS) contributes to more SIS realiability, thereby ensuring more safety and lower cost. IEC 61508 and ISA TR.84.02 provide the PFD detemination formulas. However, these formulas suffer from an uncertaity issue due to the inclusion of uncertainty sources, which, including high redundant systems architectures, cannot be assessed, have perfect proof test assumption, and are neglegted in partial stroke testing (PST) of impact on the system PFD. On the other hand, determining the values of PFD variables to achieve the target risk reduction involves daunting efforts and consumes time. This paper proposes a new approach for system PFD determination and PFD variables optimization that contributes to reduce the uncertainty problem. A higher redundant system can be assessed by generalizing the PFD formula into KooN architecture without neglecting the diagnostic coverage factor (DC) and common cause failures (CCF). In order to simulate the proof test effectiveness, the Proof Test Coverage (PTC) factor has been incorporated into the formula. Additionally, the system PFD value has been improved by incorporating PST for the final control element into the formula. The new developed formula is modelled using the Genetic Algorithm (GA) artificial technique. The GA model saves time and effort to examine system PFD and estimate near optimal values for PFD variables. The proposed model has been applicated on SIS design for crude oil test separator using MATLAB. The comparison between the proposed model and PFD formulas provided by IEC 61508 and ISA TR.84.02 showed that the proposed GA model can assess any system structure and simulate industrial reality. Furthermore, the cost and associated implementation testing activities are reduced.

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