Fabrication and operation testing of a dual resonance pulse transformer for PFL pulse charging

A high-voltage oil-submerged helical strip/wire type pulse transformer has been fabricated for charging of a Blumlein pulse-forming line (PFL). As a primary coil, a copper strip of 25 mm width was wound helically around a mono cast (MC) nylon cylinder. For a secondary coil, a copper enameled wire of 1 mm in diameter was wound around a half-conical cylinder in order to provide insulation between the two windings. The device has a coupling coefficient of 0.76, and a tuning inductor of 2.5 μH was inserted in the primary circuit to operate in the dual resonance condition. The maximum energy transfer efficiency and gain were measured to be 50% and 18.3, respectively. The transformer could charge a Blumlein PFL to 370 kV.