Development of a double stranded cable superconductor for 70 MW class superconducting generator with quick response type

Abstract

Abstruc+We have been developing a 70 M W class model generator aiming at a 200 MW class pilot machine. The superconductor developed for field winding of generator has a configuration of double stranded cable, composed of NbTi, Cu and CuNi. The strand is insulated by formvar and seven strands make a 1st stage cable. Eleven 1st stage cables make a 2nd stage cable, and are compacted to rectangular cross section. The inter -strand resistance and A.C.loss of superconductors are measured under the conditions of compressive mechanical force up to 19.6 MPa to simulate the centrifugal force of the generator rotor winding. From those results, we consider the relation between inter -strand resistance and inter -strand coupling loss. Based on those results, ,we are designing the superconductors for the 70 MW class model generator with quick response, taking the insulation of the strand into account.

AC losses in a superconductor for the quick response type 70 MW class superconducting generator

“…Assuming that the eddy current loss in the strand without the sheath is neglected, we consider the eddy current loss P,, due to the eddy current I,, in the sheath. ( see Fig.6 ) 6. Eddy current loss in the sheath As with the coupling losses, we assume that the eddy current path is as shown Fig.7.…”

“…P, along the current path in Fig.6 is given by w,12 w, w,12 w, 12 additional fins in the Cu sheath to the strand without fin, we subtracted the inter-strand coupling loss from the measurement losses [6]. The values of A.C. losses at 2.5Hz normalized by the Type A A.C. losses are shown in Table 111.…”