Case history: electronically controlled fault current limiters allow inplant switchgear to be interconnected

The growth of industrial plant power systems, through either system interconnection or paralleling of generation, results in the increase of available short-circuit fault current, which can exceed the interrupting capacity of existing plant switchgear. Complete replacement of the switchgear may not be economical. As an alternative, a short-circuit current-limiting device can reduce the magnitude of fault current to an acceptable level. This paper reviews an actual installation of three three-phase electronically controlled fault current limiters (FCLs) in a pulp and paper mill. The FCLs allow three 12.5 kV 500 MVA switchboards to be interconnected with two 12.5 kV 750 MVA switchboards.