Development and test in grid of 630 kVA three-phase high temperature superconducting transformer Frontiers of Electrical and Electronic Engineering in China    2009, 4 (1): 104-113.   DOI: 10.1007/s11460-009-0010-5
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Fig.7 Optimized cross-section of current lead

Extracts from the Article

ddz[Ak(T)dTdz]-m˙Icp(T)dTdz+ρ(T)It2A=0,

(1)

where A is cross-section, k( T) denotes thermal conductivity, c _p( T) is specific heat, ρ(T) is resistivity, T is the temperature along the lead, I _t is transport current, and m˙I is the mass flow rate of the boiled cryogen gas. The optimized cross-section of the current lead is about 60 mm2 by means of simulation. Figure 7 illustrates the test results of heat-leakage with different input losses, which simulates load loss of the transformer, while the abscissa and vertical-coordinate represent simulated load loss and evaporation of liquid nitrogen per hour respectively. The results indicate that the optimum cross-section of the current lead is 64 mm2 close to the simulation. As a result, the cross-section of the LV windings is chosen to be 65 mm2 in the proposed HTS transformer.