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The transformer type superconducting fault current limiter consists of a series transformer and a superconducting current limiting device. The primary winding of the transformer is connected in series with the power transmission line, and the secondary winding is short-circuited by the superconducting current limiting device. However, as the magnetic saturation of the transformer iron core affects the current limiting function, its detailed investigation is necessary. In this paper, a detailed experimental investigation of the magnetic saturation of the transformer type superconducting fault current limiter is carried out. It is shown that the primary current shows a high peak due to magnetic saturation just after the S-N transition of the device, and that the value and polarity of this current peak vary with the value of fault phase angle. It is also shown that the current peak due to magnetic saturation is influenced by the resistance included in the short circuit at fault occurrence. These results can be used as a basis for the design of the transformer type fault current limiter. [ABSTRACT FROM AUTHOR]

The superconducting fault current limiters' have been expected as a possible type of power apparatus to reduce the fault current in the power system. The transformer type superconducting fault current limiter, which consists of a series transformer and a superconducting current limiting device, is one type of the superconducting fault current limiter. In this paper, the influences of the load power factor on the current limiting characteristics are analyzed. The analyses are carried out based on per unit system, and the differences of the current limiting characteristics caused by different shunt impedances (inductive and resistive shunt) are also discussed. The transient performance considering the magnetic saturation is also analyzed, and it is turned out that the inductive shunt is more effective to reduce the peak of the transmission line fault current. The experimental results obtained by using a 5 kVA-class experimental fault current limiter are shown to justify the analyses. [ABSTRACT FROM AUTHOR]

The transformer type superconducting fault current limiter is one of the fault current limiters which have been proposed to reduce the fault currents in power transmission lines. In this paper, the use of shunt impedance is proposed in order to adjust the amplitude of the fault current and satisfy the required condition as a protective device. The current limiting performance of the transformer type superconducting fault current limiters with the shunt impedance is analysed theoretically. The current limiting performances with inductive shunt and with resistive shunt are compared. The experimental results obtained by using a 5 kVA-class experimental fault current limiter are shown to justify the theoretical analyses. [ABSTRACT FROM AUTHOR]

Various types of fault current limiters have been proposed to reduce the fault currents in power transmission lines. The transformer type superconducting fault current limiter is one of the fault current limiters, and has many advantages such as design flexibility. By using an experimental fault current limiter, the short-circuit fault test was carried out for different fault phase angles. From the results of the experiments, it is confirmed that the transmission line fault current is seriously affected by the magnetic saturation of the transformer core. This has to be considered in the design of the transformer. Thus, in this paper, the transient characteristics of the transformer type super-conducting fault current limiter are analyzed by the numerical simulation considering the magnetic saturation of the transformer iron core and the time-dependent resistance of the current limiting device. The analysis is carried out by using the parameters obtained from the experimental superconducting fault current limiter. From the results of the analyses, the influence of the transformer core is clarified. [ABSTRACT FROM AUTHOR]

This paper describes recent technical challenges and the progress toward the realization of the optical transport network (OTN) based on 43 Gb/s channel. We describe the new digital frame format "OTU3: Optical Channel Transport Unit 3," which is standardized in ITU-T for OTN, for the enhancement of the network management capability in the OTN based on 43-Gb/s channels. We first proposed 43-Gb/s/ch dense wavelength-division multiplexing (DWDM) dispersion-managed transmission system using carrier-suppressed return-to-zero (CS-RZ) format that has several attractive features; it advances the evolution of OTN into 100 GHz-spaced long-haul DWDM transport networks. The first wavelength-division multiplexing (WDM) field trials confirmed the superiority of CS-RZ format in the DWDM transmission performance for the first time. The first 1 Tb/s (25 × 43 Gb/s) WDM field trial confirmed the excellent network management capability of OTU3 in future data-centric OTN using the newly developed 43-Gb/s OTN line-terminal prototype. [ABSTRACT FROM PUBLISHER]

The optical transport network (OTN) based on 43-Gb/s channels is expected to be the carriers' next-generation core network. This paper discusses its system architecture, from the requirements of services, protection, and management, and shows a feasible scenario to ensure the rapid penetration of the 43-Gb/s-based OTN. It also describes the design concept and functions of the first 43-Gb/s OTN line terminal. The line terminal deploys time-division multiplexing to handle client signals and provides high-quality, multiple transparent services, such as synchronous optical network/synchronous digital hierarchy and gigabit Ethernet. The configuration and features of the actual fabricated system are described. [ABSTRACT FROM PUBLISHER]

We show the advantages of distributed erbium-doped fiber amplifiers (EDFAs) over lumped EDFAs. Using the distributed EDFA for 50%-100% of the transmission line lessens the signal degradation compared to the conventional transmission line. We also show the feasibility of the gain-flattened d-EDFA transmission line. An experiment shows that the gain peak is shifted and flattened at low pump powers [ABSTRACT FROM PUBLISHER]