Steep fronts at transient recovery voltages appearing with the interruption of inrush currents of transformers
✍ Scribed by Shigemitsu Okabe; Masanori Koto; Tadashi Koshizuka; Susumu Nishiwaki; Nobuyuki Takahashi; Toshiyuki Saida; Satoru Yanabu
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 312 KB
- Volume
- 135
- Category
- Article
- ISSN
- 0424-7760
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✦ Synopsis
High lightning overvoltages do not appear in underground substations connected to transmission cables. Consequently, it is very important to thoroughly investigate switching overvoltages and to achieve rational insulation coordination for apparatus installed in such underground substations. This paper discusses the occurrence of steep fronts at transient recovery voltages (TRV) appearing at circuit breakers when the inrush currents of transformers are interrupted. Caused by a steep front at the TRV, reignitions occur at circuit breakers, resulting in the generation of high overvoltages with high frequencies. The overvoltages are among the highest switching overvoltages appearing at the terminal of a transformer.
The authors clarified the mechanism of the generation of steep fronts at TRV by means of EMTP analysis, as well as by carrying out tests in a high-power laboratory.