Summary
Phase-Shifting Transformers (PSTs) are critical assets for power flow control, congestion management, and grid stability in modern transmission systems, with growing relevance also in distribution networks due to renewable integration. Their operational importance requires a condition-assessment approach that goes beyond factory acceptance testing and focuses on design-aware, on-site electrical diagnostics throughout the service life. This paper presents a structured methodology for field testing of PSTs, linking transformer topology, core configuration, and load tap changer (LTC) arrangement to feasible measurement methods, test sequences, and data interpretation.
Read more Read lessKey PST design variants – single- versus dual-core, direct versus indirect phase-shift regulation, and symmetrical versus asymmetrical configurations - are shown to significantly influence test accessibility, short circuit impedance behaviour, excitation characteristics, and
LTC diagnostics. A rewiring-optimised test sequence is proposed to reduce outage time while ensuring comprehensive coverage, from basic insulation and ratio measurements to advanced diagnostics such as frequency-dependent dielectric response, SFRA, FRSL, zero-sequence impedance, and specialised LTC assessment using dynamic current measurement or vibroacoustic methods.
Beyond fault detection, the study highlights the role of field test data in establishing reliable baselines, supporting trend analysis, and validating electromagnetic models. These validated models are essential for protection studies, short circuit simulations, and verification of complex protection schemes, ultimately improving operational reliability and risk-based asset management of PSTs.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | A2_11980_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | Austria |
| Study committees | |
| File size | 940 KB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
ALBERT Dennis - OMICRON electronics GmbH; PIRKER Alexander - VUM Verfahren Umwelt Management GmbH; BEDNARCZYK Tomasz - OMICRON electronics GmbH; ENGSTLER Bernhard - OMICRON electronics GmbH
