Overview
IEC TR 62066:2002 is an IEC Technical Report that gives general, practical information on surge overvoltages and surge protection in low-voltage a.c. power systems. Published in 2002, it surveys the different types of overvoltages (lightning, switching, temporary and system-interaction overvoltages), describes typical magnitudes, durations and frequencies of occurrence, and provides high-level guidance on selecting and applying surge protection measures based on availability and risk considerations.
Key Topics
- Types of overvoltages
- Lightning-induced surges: coupling mechanisms, transfer from higher-voltage networks, induction and direct flash effects.
- Switching overvoltages: transient resonance, circuit-breaker and fuse operations, high-frequency components.
- Temporary overvoltages: faults and earth-return conditions that produce sustained elevated voltages.
- System interaction overvoltages: interactions between power and communications systems and other services.
- Characterization of surges
- Typical surge magnitude, duration and statistical frequency distributions (qualitative and survey-based).
- Surge protection principles
- Role and placement of surge protective devices (SPDs) in power distribution systems, coordination among SPDs, and consideration of SPD disconnectors.
- Selection criteria that account for system configuration, availability requirements and acceptable risk.
- Practical installation considerations
- Earthing and cabling good practices, lead lengths and connection layout that affect SPD performance (see informative Annexes, including earthing/cabling guidance).
- Interactions between SPDs and equipment to be protected; energy coordination and limiting voltages.
Applications and Who Uses This Standard
IEC TR 62066 is a practical reference for professionals involved with low-voltage power distribution and protection, including:
- Electrical design engineers and consultants specifying surge protection for buildings and industrial installations
- Utility and distribution engineers assessing transferred lightning risk from MV networks
- Specifiers and manufacturers of SPDs looking for application guidance
- Facilities managers, installers and maintenance personnel implementing earthing and SPD installation best practice
- Risk-assessment teams and safety/compliance officers determining protection levels to meet availability requirements
Use cases include defining SPD placement at service entrances and distribution boards, coordinating multi-stage SPDs, assessing the need for protection against lightning vs. switching transients, and reducing interactions between power and communication lines.
Related Standards
For product specifications and test methods, consult relevant IEC standards and the IEC Publications Catalogue (www.iec.ch). IEC TR 62066 complements standards addressing SPD performance, installation rules and earthing practices and should be used alongside applicable product and wiring standards when designing surge protection systems.
Keywords: IEC TR 62066, surge overvoltages, surge protection, low-voltage power systems, surge protective device, SPD coordination, lightning surges, switching transients, earthing, power-communications interaction.