IEC 62063: Electronic Technologies in High-Voltage Switchgear Auxiliary Equipment

Introduction and Scope

IEC TR 62063:1999, titled “High-voltage switchgear and controlgear – The use of electronic and associated technologies in auxiliary equipment of switchgear and controlgear,” is a forward-looking technical report that laid the conceptual groundwork for the modernization of high-voltage substations. Published at the turn of the millennium, it recognized that the traditional electromechanical approach to switchgear auxiliary equipment was being rapidly supplanted by electronic, microprocessor-based, and digital communication technologies. The report provides basic guidance for introducing these improvements into relevant IEC standards, enabling utilities to benefit from the full potential of electronic equipment while maintaining reliability and safety.

The standard distinguishes between two fundamental parts of any switchgear: primary equipment (the high-voltage components dedicated to power transmission and interruption) and auxiliary equipment (all the monitoring, control, protection, and communication systems that enable the primary equipment to function correctly). While primary equipment technology had evolved relatively slowly, auxiliary equipment was undergoing a revolution driven by advances in microelectronics, sensors, and digital communications.

New Concepts: Intelligent and Idealized Switchgear

One of the report’s most valuable contributions is its introduction of structured definitions that clarify the evolving landscape of switchgear technology. Two concepts are particularly important:

Intelligent switchgear is defined as switchgear with enhanced features, equipped with electronic equipment, transducers, and actuators performing not only basic functions but also offering additional capabilities especially in monitoring and diagnostics. This goes beyond simple remote control – it includes self-diagnosis, predictive maintenance indicators, and communication capabilities that enable integration into broader substation automation systems.

Idealized switchgear is defined as switchgear not subjected to any internal failure like aging, gas or oil leakage, or electrical and mechanical wear, reacting only to external events. This theoretical construct helps clarify the boundary between what a switchgear should do under perfect conditions and the additional monitoring and protection functions needed in the real world.

The report defines a three-level hierarchy of switchgear functions:

• Basic functions – Required for normal operation of idealized switchgear (e.g., opening and closing commands, interlocking).
• Non-basic (auxiliary) functions – Ensure correct operation when the idealized assumptions fail (e.g., SF6 density monitoring, operation counters, travel curve acquisition).
• Monitoring functions – Measure influence quantities affecting switchgear ability to fulfill its function (e.g., temperature, gas pressure, electrical wear tracking).

Dependability Framework: RAMS in Switchgear

IEC 62063 adopts a comprehensive dependability framework covering Reliability, Availability, Maintainability, and Safety (RAMS). This structured approach reflects the understanding that electronic auxiliary equipment introduces new failure modes that must be systematically addressed.

The report notes that deregulation of electricity markets was placing new pressures on utilities. Customers demanded higher quality and continuity of service, reduced restoration times, and lower electricity costs – all while aging infrastructure and reduced technical staff compounded the challenge. This context drove the shift from traditional time-based maintenance toward condition-based and reliability-centered maintenance (RCM) strategies enabled by electronic monitoring.

System Architecture and Communication

A significant portion of IEC 62063 addresses the evolution of system architecture in substations. The traditional approach used hardwired electromechanical relays with point-to-point connections – reliable but inflexible and difficult to diagnose. The report describes a progression toward distributed architectures where intelligent electronic devices communicate over digital networks.

Key architectural considerations include:

Functional architecture: The report decomposes substation functions into hierarchical levels – station level, bay level, and process level – a concept that later became foundational in IEC 61850. Each level has specific time requirements, with process-level functions (protection, fault detection) requiring response times in milliseconds, while station-level functions (monitoring, reporting) can operate in seconds.

Interoperability: The report emphasizes the urgent need to standardize communication protocols to avoid “confusing situations” arising from multiple non-standard approaches. It explicitly calls for working groups within SC 17A and TC 57 to address this – work that directly contributed to the development of IEC 61850.

Transducers and actuators: Electronic transducers (voltage, current, pressure, density sensors) are replacing conventional electromechanical transformers and relays. These provide higher accuracy, wider dynamic range, and digital outputs that can be directly integrated with monitoring systems.

Temporary connections: Diagnostic ports and temporary communication connections are recommended for commissioning and maintenance, separate from the permanent control wiring. This allows testing and data retrieval without compromising operational security.

Monitoring, Condition-Based Maintenance, and RCM

IEC 62063 provides a detailed treatment of monitoring strategies and their relationship to maintenance philosophies. It defines three maintenance approaches: corrective (fix after failure), preventive (service at fixed intervals), and condition-based (maintenance triggered by monitored parameters). The report advocates for reliability-centered maintenance (RCM), a structured methodology that defines maintenance requirements based on the criticality of equipment failure, its probability, and its effect on overall system reliability.

Specific monitoring functions recommended for modern switchgear include:

• SF6 gas density monitoring (for gas-insulated switchgear)
• Operation counter with contact wear estimation
• Closing and opening time measurements
• Travel curve acquisition and analysis
• Accumulated breaking current tracking
• Motor and spring charging mechanism status
• Partial discharge detection for insulation monitoring

Engineering Design Insights

Several practical lessons emerge from IEC 62063 for engineers designing or specifying switchgear auxiliary systems. First, the electromagnetic compatibility (EMC) environment in substations is extremely harsh, and electronic auxiliary equipment must be designed with adequate immunity. The report references IEC 61000-5 series for installation and mitigation guidelines, particularly for earthing and cabling.

Second, the transition to electronic systems requires careful attention to power supply reliability. Electronic auxiliary equipment is more sensitive to voltage sags, interruptions, and transients than electromechanical alternatives. Adequate auxiliary power design, including UPS backup and DC supply redundancy, is essential.

Third, the report’s emphasis on clear interface definitions and manufacturer responsibility boundaries remains highly relevant. In a modern digital substation, a single communication network carries protection, control, monitoring, and metering data. Clear specification of performance requirements for each data class – including latency, availability, and security – is essential for system integrity.

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