Comparison Between the Fault Current Limiting Performance of Bi-2212 Bifilar Components and 2G YBCO Coils

Short-circuit tests with commercial Bi-2212 and with a YBCO 2G tape components were performed. The Bi-2212 bulk coil has been recently improved by the manufacturer, exhibiting higher homogeneity and better transport properties than previous ones. Such bulk components consist of a shunted bifilar coil (
$I_{c} = 400\ \hbox{A}$
at 77K). The YBCO 2G tape component consist of two antiparallel 2G shunted coils (
$I_{c} = 1200\ \hbox{A}$
at 77 K). Fault current limiting tests were performed under asymmetrical prospective currents varying from 1
$\hbox{kA}_{\rm rms}$
(2.7
$\hbox{kA}_{\rm peak}$
) to 30
$\hbox{kA}_{\rm rms}$

$\hbox{kA}_{\rm rms}$
(80
$ \hbox{kA}_{\rm peak}$
). The source voltage (Vo) was also varied in order to evaluate the influence of Vo on the limited current (138–400
$\hbox{V}_{\rm rms}$
). For the same Vo value (200
$\hbox{V}_{\rm rms}$
), the Bi-2212 components limited prospective currents as high as 80
$\hbox{kA}_{\rm peak}$
to about 6.5
$\hbox{kA}_{\rm peak}$
(first peak) and less than 1.5
$\hbox{kA}_{\rm rms}$
, whereas the YBCO 2G tape component limited the same prospective currents to less than 5
$\hbox{kA}_{\rm peak}$
(first peak) and less than 2.5
$\hbox{kA}_{\rm rms}$
. The YBCO 2G component presents a faster actuation than the Bi-2212 component.