High-voltage transmission line transformer based on modern cable technology

Abstract

A high-voltage transmission line pulse transformer has been constructed based on modern cable technology. The transformer has been successfully tested for secondary voltages up to 85 kV. The high-voltage cable is equipped with a resistive layer (semicon) on the inner conductor and on the inside of the outer conductor. Semicon cables are commonly used in high-voltage transmission of electrical power. This article describes a transformer design that uses the screen in the coaxial cable as primary winding and the inner conductor as secondary. The coupling factor for the single layer transformer is 0.8. This high coupling factor is achieved due to the coaxial structure. The single layer transformer was tested in an existing power-conditioning system, in which an output voltage of 85 kV was achieved. The pulse had 1-/spl mu/s duration over a 15-/spl Omega/ load. The high voltage cable with PEX insulation proved to withstand very high stress (85 kV/mm). This type of transformer is useful in applications where weight is an important factor. The simple design ensures low cost manufacturing.