Development of kA Class Fault Current Limiting Unit with YBCO Thin Films

Abstract

A kA-class fault current limiting unit (FCL unit) with YBCO thin films has been developed. The size of the YBCO film on a sapphire substrate with a metal shunt layer is 3 cm in width and 10 cm in length. The kA class unit consists of eight films in parallel. A polygonal arrangement of the YBCO films selected to keep the current distribution uniform. Moreover, the return pass of the current is set at the center axis of the unit. The model, connected to two units in series, was tested for normal operation and current limitation. The model carried 1 kA for 1 hour and 1.2 kA for 5 min without quench at normal operation, and the current distribution between the films was uniform. The short circuit tests were performed against a power line that has a prospective fault current of 8.9 kA. A total of eight tests were successfully carried out at 200 V, 3.5 cycles, and the model limited the fault current to 1.2 kA.

Resistive-Type Superconducting Fault Current Limiters: Concepts, Materials, and Numerical Modeling

“…Iin the same period other no less important designs were also proposed by companies like Toshiba in Japan [16]. Then, in the next decade most of the research on SFCL based upon YBCO thin films was mainly dominated by Japan [17]- [20] and Korea [21] by pursuing some novel designs.…”

Characteristics of Resistive Fault Current Limiting Elements Using YBCO Superconducting Thin Film With Meander-Shaped Metal Layer

“…However, one of the most important challenges of this type of FCL is a design of large-capacity FCL. While series and parallel connection techniques of FCL elements are inevitably important [6], the increase in the power capacity of a single FCL element is also strongly requested. Therefore, we have designed a FCL element whose superconducting layer is deposited on almost whole area of the sapphire substrate but a gold layer is deposited in the shape of meander on the superconductor [7], [8].…”