What is the difference between IEC 61508 and 13849?

In the field of industrial automation, safety plays a crucial role in ensuring that machines operate reliably and do not pose any harm to humans or the environment. To achieve this, various safety standards have been developed for different industries. Two of the most commonly used safety standards are IEC 61508 and IEC 13849. Although both standards deal with functional safety, they differ in scope, approach, and application. In this article, we will explore the differences between IEC 61508 and 13849.

Scope and Application

IEC 61508 is a generic standard that provides guidelines for achieving functional safety in electrical, electronic, and programmable electronic safety-related systems. It applies to a wide range of industries such as manufacturing, chemical, oil and gas, and nuclear power. This standard focuses on the entire safety lifecycle, starting from concept development to design, implementation, operation, and maintenance of safety systems.

On the other hand, IEC 13849 specifically targets safety-related control systems used in machinery applications. It is an industry-specific standard that complements IEC 61508 by providing more detailed requirements for the design and validation of safety functions. It is widely adopted in sectors like automotive, robotics, packaging, and machine tools.

Approach and Methodology

IEC 61508 follows a risk-based approach to functional safety, where the level of risk determines the required safety integrity level (SIL). SIL is a measure of the effectiveness of a safety function in reducing the risk to an acceptable level. The standard provides techniques and methods for hazard analysis, risk assessment, and determination of SIL, which helps in designing safety systems accordingly.

In contrast, IEC 13849 uses a performance level (PL) concept to evaluate the safety performance of control systems. PL is determined based on the probability of dangerous failures and their severity. The standard provides a methodology for calculating PL, considering aspects such as diagnostic coverage, system architecture, and component reliability.

Validation and Certification

Both standards emphasize the importance of validation and certification processes to ensure the integrity and credibility of safety systems. However, the procedures for validation and certification differ between IEC 61508 and IEC 13849.

In the case of IEC 61508, compliance with the standard can be demonstrated through various means such as design reviews, testing, and analysis. Additionally, third-party assessment and certification bodies play a crucial role in providing independent verification of compliance.

For IEC 13849, the standard itself provides a framework for evaluating the performance level achieved by safety-related control systems. The evaluation may involve documentation review, testing, and assessment of the safety functions. The responsibility of verifying compliance lies mainly with the manufacturer or authorized organizations.

In conclusion, while both IEC 61508 and IEC 13849 aim to enhance functional safety, they differ in terms of scope, approach, and application. IEC 61508 provides generic guidance applicable to a wide range of industries, whereas IEC 13849 focuses on safety-related control systems used in machinery applications. Understanding these differences is vital for selecting the appropriate safety standard based on the specific industry and application requirements.