Generation HTS Wire Research Articles

Development Status of AMSC Amperium® Wire

AMSC produces Second Generation (2G) HTS wire for utility power applications as well as coil, motor and generator solutions. In this paper, various types of AMSC's Amperium® wire suitable to power cables, fault current limiters and coils are reviewed. In addition, recently developed performance-improvements in amperage, reduced ac power loss and mechanical properties are summarized. The introduction of thicker HTS layers coupled with optimized heat treatments to enhance critical current density dramatically improve both cable and coil wire current-carrying capability. A non-magnetic RABiTSTM substrate has now been developed to the point where it is compatible with the manufacturing process and capable of sustaining large critical currents. Finally, the ability of Amperium® wires to withstand cable-winding stresses, and to exhibit the high transverse c-axis strength critical to the reliability of the wire in coils, are discussed.

Fabrication and Characterization of 3-T/102-mm RT Bore Magnet Using 2nd Generation (2G) HTS Wire With Conducting Cooling Method

A conduction-cooled high-temperature superconducting magnet using 2nd generation HTS wire, which has a room-temperature bore 102 mm in diameter, has been developed and tested up to 3 T with the operating temperature of 20 K. The magnet consists of 22 double pancake coils (DPCs) with an inner diameter of 140 mm and outer diameter of 182 mm. Twenty-two double pancake coils were tested separately at 77 K for checking the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IV</i> -curve. Selected DPCs were resistively connected by HTS tape (Splice joint), and an assembled magnet coil with the size of 182.5 mm diameter and 242 mm in height was conduction cooled by a two-stage Gifford-McMahon cryo-cooler to 20 K. Current, voltage, and field strength were measured as a function of time with various ramping up and down conditions. The resulting performance data of the assembled magnet agreed well with the expectation from FEM simulation. The aimed field homogeneity of 0.1% in 10 mm diameter sphere volume was proved when operating current was 141.6 A at 20 K with central magnetic field intensity of 2.9975 T by hall sensor. The magnetic flux density at center showed nonlinear dependence with ramping current within the range of 0.05 A/sec ~0.15 A/sec because of charging delay. However, saturated magnetic flux density showed the same value of 2.9975 T regardless of ramping rate.

Fault Current Limitation by a Transformer Type FCL Based on the Second Generation HTS Wires

A transformer type superconducting fault current limiter (FCL) for electric power grids was developed utilizing a nonlinear resistor made of the second generation HTS wire. Using of the second generation HTS wire instead of the first one was found to reduce by an order the required amount of superconducting materials. Fault current limiting action and transients in an electric circuit with the prototype FCL have been studied. The effective limitation of peak and steady state fault current was demonstrated using the FCL. The physical basis of the FCL operation was investigated by studying a superconducting-to-normal transition in the second generation HTS wires.

The Development of Second Generation HTS Wire at American Superconductor

Development of the second generation (2G) YBCO high temperature superconducting wire has progressed rapidly and its performance is approaching, and in some areas exceeding, that of first generation (1G) HTS wire. American Superconductor's approach to the low-cost manufacturing of 2G wire is based on a wide-strip (4 cm) process using a metal organic deposition (MOD) process for the YBCO layer and the RABiTS (rolling assisted biaxially textured substrate) process for the template. In addition, the wide-strip RABiTS/MOD-YBCO process provides the flexibility to engineer practical 2G HTS wires with architectures and properties tailored for specific applications and operating conditions through slitting to custom widths and laminating with custom metallic stabilizers. This paper will review the status of the 2G manufacturing scale up at AMSC and describe the properties and architecture of the 2G wire being developed and tested for various applications including in cables, coils and fault current limiters. Performance of 100 meter class, 4 mm wide wires at 77 K, self-field has reached 100 A (250 A/cm-width) with single-coat YBCO and 140 A (350 A/cm-width) with double-coat YBCO. A 5 cm inner diameter coil fabricated from the latter wire achieved 1.5 T at 64 K, confirming the capability of the wire for coil applications.

Use of Second Generation HTS Wire in Filter Inductor Coils

AMSC's process for manufacturing Second Generation (2G) YBCO High Temperature Superconductor wire provides the flexibility to engineer practical 2G conductors with various architectures. For applications with high frequency ac components, a stainless steel stabilizer is used to minimize eddy current losses. An example of such an application is the so-called Buck Inductor, a filter inductor carrying a DC current onto which a 5 KHz ac current is superimposed. Previously we reported on the development and initial testing of the first 2G HTS toroid for this application. We demonstrated a strong reduction of the ac losses with a DC bias current. In this work, we present results on a toroid using a different double pancake design with better cooling. This design allows operation of the double pancake in liquid nitrogen at high frequencies without heating effects.

AC application of second generation HTS wire

For the production of Second Generation (2G) YBCO High Temperature Superconductor wire American Superconductor uses a wide-strip MOD-YBCO/RABiTSTM process, a low-cost approach for commercial manufacturing. It can be engineered with a high degree of flexibility to manufacture practical 2G conductors with architectures and properties tailored for specific applications and operating conditions. For ac applications conductor and coil design can be geared towards low hysteretic losses. For applications which experience high frequency ac fields, the stabilizer needs to be adjusted for low eddy current losses. For these applications a stainless-steel laminate is used. An example is a Low Pass Filter Inductor which was developed and built in this work.

Study of Shunt Type SFCL Equipped with Electromagnetic Repulsion Switch for Large Capacity

Using a high temperature superconductor, we constructed and tested a model Superconducting Fault Current Limiter (SFCL). SFCL we proposed has a vacuum interrupter with electromagnetic repulsion mechanism. We set out to construct high voltage class SFCL. We produced the electromagnetic repulsion switch equipped with a 24kV vacuum interrupter (VI). There are problems that opening speed becomes late, because the larger vacuum interrupter needs the heavier weight of its contact. For this reason, the current which flows in a superconductor may be unable to be interrupted within a half cycles of current. In order to solve this problem, it is necessary to change the design of the coil connected in parallel and to strengthen the electromagnetic repulsion force at the time of opening the vacuum interrupter. Then, the design of the coil was changed, and in order to examine whether the problem is solvable, the current limiting test was conduced. We carried out a current limiting test using second generation (2G) HTS wire. The element which is used in this experiment has stainless steel stabilizer both side of the wire. As a result, we succeed in interrupting the current of a superconductor within a half cycle.

The Development of Second Generation HTS Wire at American Superconductor

The Development of Second Generation HTS Wire at American Superconductor

High Critical Current YBCO Films Prepared by an MOD Process on RABiTS Templates

The metal organic deposition (MOD) of YBCO high temperature superconducting films on RABiTS (rolling assisted biaxially textured substrates) templates has been developed at American Superconductor as a low-cost, scalable manufacturing process for the commercialization of the second generation (2G) HTS wire. The MOD process is based on the deposition of a triflu-oroacetate (TFA) based metal organic precursor film which is converted, in an ex-situ process, to the superconducting YBCO film. A major goal of the development has been achieving high critical currents. This paper reports the preparation and characterization of MOD-YBCO films with critical currents exceeding 500 A/cm-w (77 K, self-field) using a scaleable thick film approach on RABiTS templates. The high critical current films were obtained through optimization of the precursor composition, nucleation and growth conditions. The through-thickness dependence of the critical current density of MOD Alms as a function of film thickness and a correlation of the through-thickness transport properties and microstructure of the thick MOD/RABiTS samples is reported.

Progress in AMSC scale-up of second generation HTS wire

American Superconductor has successfully scaled up its low-cost, high volume second generation (2G) HTS wire process into pre-pilot scale production, with performance approaching first generation (1G) HTS wire. AMSC’s manufacturing approach is based on RABiTSTM/MOD wide strip technology, with metal organic deposition (MOD) process for the YBCO layer and the Rolling Assisted Biaxially Textured Substrate (RABiTS) process for the template. In this paper, we review the status of the 2G manufacturing scale up at AMSC and describe the properties and architecture of the 2G wire being manufactured and developed for various applications.

Second Generation HTS Wire Based on RABiTS Substrates and MOD YBCO

The performance of Second Generation (2G) high temperature superconducting wire manufactured by continuous reel-to-reel processes is nearing the 300 A/cm-width (77 K, self field) performance threshold for commercial power cable applications. The 2G manufacturing approach under development at American Superconductor is based on the combination of the RABiTS substrate-buffer technology with metal organic deposition (MOD) of the YBCO layer. The capability of this process has been demonstrated in multiple 10 meter lengths with critical currents exceeding 250 A/cm-width with high uniformity and reproducibility. Critical currents of 380 A/cm-width have been achieved in short length samples prepared by the same basic process. The incorporation of nanoparticles (nanodots) into the YBCO layer using the MOD process has resulted in a 2-fold improvement in the critical current at 65 K in a 3 T field. The research and development focus at ASMC is now directed toward the economical scale-up of the RABiTS/MOD process, optimization of the conductor properties for targeted applications and the use of 2G wire in initial demonstration applications.

Second generation YBCO coated conductors: A review

The advance in first generation Bi-2223 HTS wire has enabled the demonstration of superconducting power cables, magnetic energy-storage devices, transformers, fault current limiters and motors. However, the low irreversibility field (H*) prevents application of Bi-2223 at 77 K in any significant field. Worldwide activities are therefore, focused on developing a second-generation HTS technology based on YBCO, for whichH* (77 K) ∼ 7 T. In this paper, we discuss the status and commercial prospects of second generation HTS wire technologies. In addition, we review the recent results and discuss the prospects of future applications.