Overview
IEC 60044-8:2002 - Instrument transformers - Part 8: Electronic current transformers (ECTs) - is the International Electrotechnical Commission standard that sets requirements for newly manufactured electronic current transformers with either an analogue voltage output or a digital output. The standard applies to devices intended for use with electrical measuring instruments and protective relays at nominal frequencies from 15 Hz to 100 Hz. It defines terminology, service conditions, ratings, design, testing, marking, safety and documentation expectations for both measuring and protective ECTs.
Key topics and technical requirements
- Scope & definitions: clear definitions for measuring and protective ECTs, digital and analogue outputs, and related abbreviations.
- Service conditions & ratings: normal and special environmental conditions, altitude corrections, and rated values for digital/analogue outputs.
- Design requirements: functional and construction rules for ECTs, including low-voltage components, EMC considerations and thermal/mechanical design.
- Digital interface specifics: interface architectures (optical and copper), coding methods (e.g., Manchester), frame formats, daisy‑chain topologies and timing/clock requirements for synchronized sampling.
- Accuracy & frequency response: accuracy classes for measuring and protective ECTs, limits for current and phase error, and requirements for harmonic performance (see Annex D).
- Testing framework: classification into type, routine and special tests. Key type tests include short‑time current, temperature‑rise, impulse, wet/outdoor, RIV, transmitted overvoltage, EMC and accuracy tests. Routine tests cover terminal marking verification, power‑frequency withstand, partial discharge and accuracy checks.
- Marking & documentation: terminal and rating plate marking rules, and information to supply with enquiries, tenders and orders.
- Safety, installation & maintenance: electrical, mechanical and thermal safety requirements; transport, storage and installation guidance.
- Annexes: informative and normative annexes cover transient performance, technical data for digital and analogue outputs, harmonic testing, and accuracy graphs.
Applications and who uses this standard
IEC 60044-8 is essential for:
- Manufacturers of electronic current transformers and subassembly suppliers.
- Power utilities and substation engineers specifying metering and protection equipment.
- Protection and metering device vendors designing interfaces to digital/analogue ECT outputs.
- Test laboratories and certification bodies performing type and routine testing.
- Procurement and standards teams preparing technical specifications, tenders and compliance documentation.
Use this standard to ensure interoperability, accurate measurement, reliable protection performance and to meet regulatory or procurement requirements for modern instrument transformers.
Related standards
- Other parts of IEC 60044 (instrument transformers) for magnetic CTs/VTs and additional guidance.
- EMC, safety and power system standards referenced within the document for complementary requirements.