Overview - IEC TR 62681:2014 (Electromagnetic performance of HVDC overhead transmission lines)
IEC TR 62681:2014 is a Technical Report that provides guidance on the electromagnetic environment of high-voltage direct current (HVDC) overhead transmission lines. The report describes the major parameters used to characterize HVDC electromagnetic performance - including electric fields, ion current (space charge), magnetic fields, radio interference (RI) and audible noise (AN) - and summarizes calculation methods, measurement techniques and experimental data. Its purpose is to help engineers and planners ensure safe operation, limit environmental impact within acceptable ranges and optimize engineering costs for HVDC projects.
Key topics and technical highlights
- Electric field & ion current (space charge)
- Physical phenomena and environmental implications (static fields, space charge regions).
- Calculation approaches: semi-analytic, finite element, BPA methods and empirical EPRI/other formulas.
- Instrumentation, measurement methods and experimental results from multiple HVDC projects.
- Magnetic field
- Description of magnetic field distribution around HVDC lines and lateral ground profiles.
- Radio interference (RI)
- Corona-related RI mechanisms, RI characteristics and factors influencing emissions.
- Prediction methods: EPRI empirical formula, IREQ, CISPR bipolar line prediction and comparative analysis.
- Measurement practices and experimental RI data.
- Audible noise (AN)
- Basic principles, lateral profiles, statistical distribution and propagation.
- Calculation and empirical/semi-empirical formulas; measurement techniques and country-specific design practice.
- Guidance on complaint thresholds and recommended noise limits.
- Experimental annexes
- Case studies and measurement datasets from international projects (e.g., Bonneville, FURNAS, Manitoba Hydro, Hydro-Québec and test lines), supporting model validation and design decisions.
Practical applications - who uses this standard
- Transmission line designers and HVDC system engineers (line configuration, conductor bundling, pole spacing).
- Utilities and asset owners evaluating environmental compliance and mitigation measures.
- Regulatory authorities and planners assessing electromagnetic and acoustic impacts for permitting.
- Consultants performing EMI/EMC studies, audible-noise assessments and environmental impact analyses.
- Researchers validating models against measured HVDC field, RI and AN data.
Related standards and references
- CISPR recommendations and measurement procedures for radio interference (referenced in TR).
- EPRI empirical methods and utilities’ technical practices (summarized and compared).
- National design codes and environmental noise/EM exposure limits (TR provides international design practice examples).
IEC TR 62681:2014 is a practical reference for understanding, predicting and measuring the electromagnetic effects of HVDC overhead lines, helping stakeholders balance operational safety, community impact and project cost-efficiency.