Circuit Breakers

Power electronic switches have been considered for load switching ever since their invention. This is because semiconductor switches enable fast, arc-less, reliable and maintenancefree switching. The main disadvantages in relation to conventional switches (i.e. circuit breakers), however, are their sensitivity to transients, high on-state losses and the presence of leakage current. The advantages of both types of switches can be exploited by combining the semiconductor and the mechanical switch and thereby their disadvantages, arc formation and regular maintenance, can also be eliminated. For hybrid switches (HSs), both zero voltage switching (ZVS) and zero current switching (ZCS) are frequently used. A new hybrid switching topology has been developed where both ZVS and ZCS techniques are applied to the mechanical switch. The 'symbiosis' between these solid-state switching techniques and a mechanical switch eliminates several of the disadvantages, resulting in a more reliable direct current (DC) HS that requires less maintenance. The first turn-off measurement (up to 5 kA) from a prototype that has been developed for a 3-kV DC grid is presented. A. Taffone, E. Gilardi, and S.M. Tenconi are with the Ansaldo Ricerche, Corso F.M., Perrone 118, Genoa 16161, Italy B.H. Evenblij and M.A.M. Kaanders are with the TNO Defence and Safety,

The average surface ablation of poly-tetra-fluro-ethylene (PTFE) nozzles in high voltage circuit-breakers was investigated experimentally by means of the specific ablation. Experiments were done with a test device in the current and arcing time range of 2-40 kA rms and 5-17 ms, respectively. This allowed determining the dependences of the specific PTFE ablation on current and arcing time. Additionally, the specific PTFE nozzle ablation in commercial high voltage circuit-breakers was analysed in a broad range of current amplitudes and arcing times. For understanding the results more in detail, experiments with a small scale test device were performed. The different experiments yielded consistent values for the PTFE ablation. The ablation depends mainly on the total arc energy. The total ablation is given by the ablation of walls surrounding the arc and by the ablation in regions where plasma from the arc cools down. Different specific ablation values can be observed for the axial blown arc mode and the ablation controlled arc mode.

Cybersecurity of the substations in a power system is a major issue as the substations become increasingly dependent on computer and communication networks. This paper is concerned with anomaly detection in the computer network environment of a substation. An anomaly inference algorithm is proposed for early detection of cyber-intrusions at the substations. The potential scenario of simultaneous intrusions launched over multiple substations is considered. The proposed detection method considers temporal anomalies. Potential intrusion events are ranked based on the credibility impact on the power system. Snapshots of anomaly entities at substations are described. Simulation results using the modified IEEE 118-bus system have shown the effectiveness of the proposed method for systematic identification. The result of this research is a tool to detect cyber-intrusions that are likely to cause significant damages to the power grid.

Worldwide many transformer insulation failures have been reported caused by switching operations, while those transformers had previously passed all the standard tests and complied to all quality requirements . These phenomena can occur in both distribution and transmission networks. For distribution transformers, an investigation is usually only started in case of repetitive faults.

— Auto recloser Relay (AR) atau relai penutup balik otomatis dipasang pada bay penghantar Saluran Udara Tegangan Tinggi (SUTT) maupun Saluran Udara Tegangan Ekstra Tinggi (SUTET). Hal ini didasarkan pada pertimbangan bahwa saluran udara merupakan salah satu bagian sistem penyaluran yang paling sering mengalami gangguan, sebagian besar dari penyebab gangguan tersebut bersifat temporer yang akan segera hilang setelah circuit breaker trip. Agar kesinambungan pasokan tenaga listrik tetap terjaga serta batas stabilitas tetap terpelihara maka pengoperasian auto recloser sangat dibutuhkan. Pada paper ini, telah dilakukan pengujian waktu reclose (dead time) dan pengujian reclaim time sesuai dengan pedoman dari SPLN 0520 menggunakan alat uji DOBLE F6150 untuk mengkaji kesesuaian setting waktu reclose (dead time) dan waktu reclaim time pada auto recloser GEC ALSTHOM type MVTR01 dengan pertimbangan karakteristik trip close operation time circuit breaker dan setting pole discrepancy. Hasil analisis menunjukkan bahwa terjadi kegagalan auto recloser bay 150kV Cilegon Lama di Gardu Induk Mitsui diketahui saat pemeliharaan 2 tahunan. Penyebab kegagalan adalah dari status circuit breaker untuk input auto recloser tidak sesuai sehingga dilakukan penyesuaian status circuit breaker sebagai input auto recloser tersebut. Setelah dilakukan penyesuaian status circuit breaker dilanjutkan pengujian auto recloser waktu yang sesuai target setting yaitu MVTR01 SPAR (Single Phase Auto Recloser) dengan reclose (dead time) 0,49 menjadi 0,5 detik dan reclaim time 41,5 menjadi 40 detik, MVTR01 TPAR (Three Phase Auto Recloser) dengan reclose (dead time) 4,98 menjadi 5,0 detik dan reclaim time 41,5 menjadi 40 detik sehingga fungsi auto recloser dapat bekerja sesuai dengan settingnya. Keywords— auto recloser, status circuit breaker, dead time, reclaim time, bay150kV

The new IEC 62271-100 requires an extensive proof of the capability of capacitive switching for a breaker under test. For vacuum circuit breakers, dielectric properties are mainly determined by the condition and topology of the contact surfaces, which are modified by in-rush currents as well as load-breaking currents and other effects. A synthetic single-phase test device has been erected in order to simulate three-phase network conditions and to collect more data on the statistical properties of the relevant processes. The distribution of pre-ignition field strengths is evaluated for different contact strokes and surface conditions, when discharging a capacitor through the closing interrupter. On the other side, the probability of restrikes for a given switching condition defined by full contact gap d 0 and peak recovery voltage Û re is measured and compared with the cumulative probability of pre-ignition just at the field strength E= Û re /d 0 . A correlation between pre-ignition and restrike probabilities suggests a breakdown mechanism being field-emission dominated. In addition a rather strong conditioning effect has been observed at smaller contact gaps smoothening the contact surfaces.

On the roof of a wool processing company a 385 kWp PV installation is installed. When production of the installation is more than 60% of the rated power the circuit breaker trips. Measurements show high THD(U) of phase voltages and variable waveform of both voltage and current. Analysis of the installation showed that a Yy 0 transformer is installed introducing a high zero sequence field impedance. Unbalance in the injected current combined with a zero sequence impedance leads to high voltage drops and distorted phase voltages. Measurements also show high RMS values of the current in the neutral conductor. Analyses show that the tripping of the circuit breaker is caused by the measurement method of the device itself. Higher current values are calculated due to multiple zero crossings of both voltage and current. This paper gives the practical measurement results, causes of errors and the solution to the stated problems.

This paper reports a ferroresonant experience involving inductive Voltage Transformers (VT's) in a 400kV substation equipped with circuit breaker grading capacitors. Field measurements are presented and compared with ATP/EMTP simulation results, showing very good agreement. A parametric analysis has been performed to investigate the effect of the substation capacitance on the occurrence of ferroresonance. Fundamental frequency and sub-harmonic ferroresonant modes have been identified and compiled in a bifurcation diagram. The methodology presented can be used to create risk maps of avoidable switching operations or substation configurations.