NSTX upgrade power supply system

The National Spherical Torus Experiment (NSTX) is undergoing a significant upgrade. The upgrade increases the toroidal field and pulse length, adds three new diverter coils and a second neutral beam injection (NBI) system. The magnet coil power supply systems for the NSTX have been redesigned with many modifications to reflect NSTX upgrade needs. The NSTX power supply system includes three major parts. The first part is the DC power supplies for the magnet coils. The second is the power supply real time control system. The third is the coil and power supply protection system. In this paper, a brief overview of the power system upgrade is presented.