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IEC 60255: Electrical Relays - Performance Requirements

IEC 60255: Electrical Relays - Performance Requirements




The International Electrotechnical Commission (IEC) standard 60255, titled "Electrical Relays - Performance Requirements," establishes the performance criteria and specifications for electrical relays used in various applications to control, protect, and monitor electrical systems. Relays play a critical role in the operation of power systems, automation, and industrial control applications by providing essential functions such as fault protection, circuit isolation, and signal switching. Compliance with IEC 60255 ensures that electrical relays meet international standards for performance, reliability, and safety in diverse electrical and industrial applications.


Scope of IEC 60255


IEC 60255 covers a wide range of electrical relay types, including electromagnetic, solid-state, thermal, and hybrid relays, used in power systems, protection schemes, control circuits, and automation applications. The standard addresses the performance requirements, characteristics, testing procedures, and reliability criteria for electrical relays to ensure proper operation, response time, accuracy, and coordination in various operating conditions. It encompasses relay design, functionality, ratings, settings, and behavior under normal, fault, and transient conditions.


Key Requirements of IEC 60255


The key requirements of IEC 60255 focus on the following aspects to ensure the performance and reliability of electrical relays:


1. Functional Performance: IEC 60255 specifies the functional requirements for electrical relays, including pickup, dropout, timing, sensitivity, static and dynamic characteristics, and response times. Relays must demonstrate accurate, reliable, and consistent performance in detecting faults, initiating trips, and switching circuits to ensure proper protection, control, and operation of electrical systems.


2. Stability and Sensitivity: The standard addresses the stability, sensitivity, and operational behavior of relays under varying conditions, such as transient disturbances, ambient temperature changes, supply voltage fluctuations, and electromagnetic interference. Relays should maintain stable performance, sensitivity, and immunity to external factors that could affect their operation and response time.


3. Accuracy and Coordination: IEC 60255 defines the accuracy requirements, tolerances, and coordination settings for relays used in protection, control, and monitoring applications. Relays must operate within specified tolerances, settings, and time bands to ensure reliable coordination with other protection devices, circuit breakers, and system components in a coordinated and selective manner.


4. Testing and Verification: The standard outlines testing procedures, performance verification methods, and qualification criteria for evaluating the compliance of relays with the requirements of IEC 60255. Relays undergo various tests, including function tests, stability tests, accuracy tests, and performance assessments, to validate their operation, response characteristics, and reliability under normal and fault conditions.


Benefits of Compliance with IEC 60255


Compliance with IEC 60255 offers several benefits to manufacturers, utilities, system operators, and end-users utilizing electrical relays:


1. Reliability and Protection: Electrical relays that meet the performance requirements of IEC 60255 provide reliable protection, accurate fault detection, and fast response times in electrical systems, enhancing the safety, reliability, and performance of power distribution, control circuits, and automation applications.


2. Coordination and Selectivity: By adhering to the coordination and accuracy criteria of IEC 60255, relays ensure proper coordination, selective tripping, and coordinated protection schemes within complex electrical networks, preventing cascading failures, minimizing system downtime, and enhancing overall operational resilience.


3. Compliance with Standards: Conformance to the requirements of IEC 60255 ensures that electrical relays comply with international standards, industry best practices, and regulatory expectations for performance, reliability, and safety in electrical protection, control, and automation applications.


4. Efficiency and Optimization: Reliable and accurate electrical relays compliant with IEC 60255 help improve the efficiency, performance, and operational effectiveness of electrical systems, reducing downtime, enhancing system stability, and optimizing energy management in industrial, commercial, and utility environments.




IEC 60255 plays a crucial role in defining the performance requirements for electrical relays used in protection, control, and automation applications to ensure reliable, accurate, and coordinated operation in diverse electrical systems. Compliance with the standard enables manufacturers, utilities, system operators, and end-users to deploy electrical relays that meet international standards for performance, reliability, and safety. By following the guidelines of IEC 60255, stakeholders in the electrical industry can leverage high-quality, compliant relays to enhance electrical system protection, control functionalities, and operational reliability in critical applications.



Contact: Eason Wang

Phone: +86-13751010017


Add: 1F Junfeng Building, Gongle, Xixiang, Baoan District, Shenzhen, Guangdong, China

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