AC POWER SYSTEM The power systems for the Tokamak Physics Experiment The major experimental power loads consist of the PF (TPX) supply the Toroidal Field (TF), Poloidal Field (PF), system and the heating & current drive systems [2]. Field Error Correction (FEC_, and Fast Vertical Position Additional loads consist of the PPPL facility conventional Control (FVPC) coil systems, the Neutral Beam (NB), Ion loads, plus those associated with the TPX auxiliary systems Cyclotron (IC), Lower Hybrid (LH) and Electron Cyclotron (TF, cryogenic system, and all additional loads). For the (EC) heating & current drive systems, and all balance of plant upgrade options, it is assumed that no additional power is loads. Existing equipment from the Tokamak Fusion Test demanded by Option I, while option II requires an increase in Reactor CYFTR), including the motor-generator (MG) sets and heating & current drive power, and option III is assumed to the rectifiers, can be adapted for the supply of the TPX PF demand the same peak power as option II only for a longer systems. A new TF power supply is required. A new duration. The approximate peak power levels are summarized substation is required for the heating & current drive systems in the following table. (NB, IC, LH, and EC). The baseline TPX load can be taken directly from the grid without special provision, whereas if all Load _ _io.K.I]21_ upgrade options are undertaken, a modest amount of reactive (MW/MVAR) (MW/MVAR) compensation will be required. This paper describes the conceptual design of the power systems [1], with emphasis on PPPL Facilities 5/3.75 5/3.75 the AC, "IF, and PF Systems, and the quench protection of the TPX Aux Sys 20/15 20/15 superconducting coils. TPX PF (ramp) 75/* 75/* TPX PF Omrn) 10]* 10/*