What is the difference between IEC 62443 and ISA 99 ?

IEC 62443 and ISA 99 are both recognized global standards for ensuring functional safety of systems. While both standards outline requirements for the design, implementation, operation, and maintenance of safety instrumented systems (SIS), there are key differences between the two.

Scope and Application

ISA (International Society of Automation) is a non-profit professional association that primarily focuses on standards, technical resources, and education in the field of automation. ISA develops and promulgates standards that encompass a wide range of areas within industrial automation, such as process control systems, safety instrumented systems, cybersecurity, and industrial communications. ISA's standards are more specific to automation technologies and target professionals working in this field.

On the other hand, IEC 62443 is an international standard that outlines requirements for the design, implementation, operation, and maintenance of safety instrumented systems. IEC 62443 is a product of the IEC 61511 standard, which is a widely accepted standard for ensuring functional safety of systems.

Differences Between IEC and ISA

The primary difference between IEC and ISA is their scope and coverage. While IEC addresses broader electrical and electronic technologies, ISA concentrates on automation-specific domains. This makes ISA's standards more specialized and tailored to the needs of automation professionals.

Another distinction is the organizational structure. IEC operates through national committees where each country has equal representation, while ISA functions mainly through geographical sections, divisions, and technical committees. This structural difference reflects varying approaches in consensus-building and decision-making processes.

Conclusion

In conclusion, while both IEC 62443 and ISA 99 are recognized global standards for ensuring functional safety of systems, they have distinct differences in their scope and coverage, as well as their organizational structure. The choice of which standard to follow will depend on the specific application and requirements of the system being designed. It is important to carefully evaluate the similarities and differences between the two standards to ensure that the system is compliant with both requirements.