In the field of electrical engineering, two important standards that govern the design and testing of low voltage switchgear and control gear assemblies are IS 8623 and IEC 61439. While both standards aim to ensure the safety and performance of these assemblies, they have some key differences in terms of scope, requirements, and testing methods. This article provides an in-depth comparison between the two standards, shedding light on their similarities and disparities.
Scope and Requirements
IS 8623, which stands for "Low-voltage switchgear and control gear assemblies - General rules," is an Indian standard that specifies the general requirements for the design, construction, testing, and documentation of low voltage switchgear and control gear assemblies. It covers a wide range of assemblies, including distribution boards, motor control centers, and power factor correction panels. On the other hand, IEC 61439 is an international standard that encompasses a broader scope, providing guidelines for low voltage switchgear and control gear assemblies as well as specific types such as type-tested assemblies (TTA), partially type-tested assemblies (PTTA), and free-standing enclosures (FSE). The scope of IEC 61439 also includes clauses relating to environmental aspects, such as temperature rise limits and resistance to ultraviolet (UV) radiation.
Design Verification
Both IS 8623 and IEC 61439 require design verification of the assemblies. However, the two standards employ different approaches for achieving this. IS 8623 adopts a prescriptive approach, where specific requirements and tests are provided for various components of the assembly, such as busbars, circuit breakers, and terminals. Compliance with IS 8623 is typically demonstrated by conducting individual tests on these components and ensuring that they meet the specified criteria. On the other hand, IEC 61439 adopts a performance-based approach, focusing on the overall assembly's capability to withstand normal operating conditions and fault conditions. Instead of testing individual components, IEC 61439 requires performing integrated tests that simulate realistic scenarios, such as short-circuit and temperature rise tests, to validate the assembly's reliability and safety.
Testing and Certification
Both IS 8623 and IEC 61439 emphasize the importance of testing and certification for ensuring the quality and safety of switchgear and control gear assemblies. However, there are differences in the testing methods and certification requirements. IS 8623 mandates type testing of critical parameters like insulation resistance, dielectric strength, and mechanical endurance. It also requires the manufacturer to provide a type test report for each tested assembly. In contrast, IEC 61439 offers more flexibility in terms of testing, allowing manufacturers to conduct both routine tests and sample type tests. The standard requires the manufacturer to provide design verification records, assembly instructions, and a declaration of conformity. Certification bodies can then evaluate these documents along with test reports to grant certification based on compliance with IEC 61439.
Nina She