Type 300 series autorecloser has ratings of up to 29.3 kV,
800 A and 16 kA. It houses a vacuum interrupter in each phase which has an aluminium
outer body filled with a patented solid foam insulation. The unit uses an otherwise
conventional vertical porcelain insulator and a removable polymer horizontal insulator. This latter insulator facilitates access for the removal of the phase current
transformer.