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Mercury superconductor samples doped with rhenium, Hg0.82Re0.18Ba2Ca2Cu3O8+d, were produced in a very narrow range of oxygen content (d = 0.05, 0.10 and 0.15). The lattice parameters indicated a slight change of the unitary cell as a function of the oxygen content. Furthermore, the reduction of the volume cell was associated with the slight increment of TC. The measurements of χac versus temperature, under external hydrostatic pressure, have shown sensitive results as a function of distinct oxygen content. In our opinion, this kind of measurement may be used as a tool to determine the oxygen content (underdoped, optimal or overdoped) of samples. For dTC/dP > 1.9 K GPa−1 the sample presents an underdoped oxygen content. One can understand that dTC/dP = (1.9 ± 0.2) K GPa−1 is associated with an intrinsic term value for the optimal oxygen doped sample, Hg0.82Re0.18Ba2Ca2Cu3O8.10.

This paper have studied the dynamic of a 2.0 MW Doubly Fed Induction Generator (DFIG) during a severe voltage sag. Using the dynamic model of a DFIG, it was possible to determine the current, Electromagnetic Force and flux behavior during three-phase symmetrical voltage dip. Among the technologies of wind turbines the DFIG is widely employed; however, this machine is extremely susceptible to disturbances from the grid. In order to improve DFIG Low Voltage Ride-Through (LVRT), it is proposed a novel solution, using Superconducting Current Limiter (SCL) in two arrangements: one, the SCL is placed between the machine rotor and the rotor side converter (RSC), and another placed in the RSC DC-link. The proposal is validated through simulation using PSCAD TM /EMTDC TM and according to requirements of specific regulations. The analysis ensure that both SCL arrangements behave likewise, and are effective in decrement the rotor currents during the disturbance.

Hg 0 82 Re 0 18 Ba 2 Ca 2 Cu 3 O 8+ polycrystalline samples were successfully obtained by using different oxygen partial pressure in the annealing treatment of the precursor ceramic. The doping state was confirmed by X-ray powder diffraction pattern analysis and by observing distinct thermopower values at room temperature. Also, the intergrain regions have shown an improvement in the critical current density when using the precursor preparation with 10% O 2 and 90% Ar (optimal doped). The optimal doped sample has presented the highest exponent of the [1 () 2 ] dependence. For the case of (Hg,Re)-1223 polycrystalline superconductor applications, the exponent can be used as a junction quality parameter.Index Terms-Critical current density, high-, (Hg,Re)-1223 samples, thermoelectric power.

A preliminary study of a small superconducting current limiter device based on Hg0.8Re0.2Ba2Ca2Cu3O8+δ, (Hg,Re)-1223 ceramic is described. A fault current test at 60Hz confirmed a reduction in the density of current value, from 1.55×102to0.82×102Apeak∕cm2. The prospective/limited density of current ratio observed was ∼1.9 for a 0.24cm thick sample, without any damage to the (Hg,Re)-1223 superconductor. A recovery test indicated that the polycrystalline sample kept its superconducting properties and had not shown modifications in its stoichiometry. In conclusion, (Hg,Re)-1223 can be used to build superconducting fault current limiter devices.