Overview
IEC TR 61869-102:2014 - Instrument transformers, Part 102 - is a Technical Report from the IEC that explains the phenomenon of ferroresonance oscillations in substations containing inductive voltage transformers. The report focuses on medium‑ and high‑voltage networks where ferroresonance can be excited by non‑linear magnetisation characteristics and capacitive coupling, potentially causing severe damage to voltage transformers and related equipment. IEC TR 61869-102 provides guidance on identification, measurement, computer simulation, and methods for avoidance and suppression of ferroresonance.
Key topics and technical coverage
The report covers practical and theoretical material relevant to engineers and technicians:
- Definition and mechanisms of ferroresonance, including steady‑state, transient, subharmonic and chaotic oscillations.
- Single‑phase and three‑phase configurations, with simplified circuit models for analysis and typical oscillogram examples.
- Inductive voltage transformer details - core magnetisation characteristics, hysteresis, circuit losses and their role in ferroresonance.
- Excitation sources such as switching operations, de‑energised feeders, and capacitive coupling between parallel lines.
- Measurement and experimental methods, including recommended test arrangements and how to capture current/voltage signals during oscillations.
- Computer simulation guidance, circuit element modelling and example simulation cases illustrating different ferroresonance modes.
- Avoidance, damping and mitigation strategies, plus a practical flow‑chart for investigation and remedy selection for existing and new substations.
Practical applications
IEC TR 61869-102 is a practical reference for addressing ferroresonance risk in real networks:
- Design and commissioning of substation bays and feeder circuits to reduce ferroresonance susceptibility.
- Selection and specification of instrument transformers (inductive VT/ PT) with attention to magnetisation behaviour and losses.
- Developing testing and diagnostic procedures for field measurement and laboratory reproduction of ferroresonance.
- Implementing mitigation measures such as secondary damping devices, connection changes, or circuit modifications to prevent equipment damage.
Who should use this standard
- Substation designers and protection engineers
- Utility planners and operations personnel
- Manufacturers of inductive voltage transformers and damping equipment
- Test laboratories and researchers conducting simulations and experimental investigations
Related standards
- IEC TR 61869-102 is part of the IEC 61869 instrument transformers series. Users should consult other parts of IEC 61869 for detailed performance and testing requirements of instrument transformers.
Keywords: ferroresonance oscillations, IEC TR 61869-102, inductive voltage transformers, substations, medium voltage, high voltage, damping, computer simulation, measurement methods.