[en] The DIII-D fusion experiment utilizes two large motor-generator sets for supplying energy to the toroidal and poloidal field coils of the tokamak. One generator has an energy capability of 2250 MJ and the other has 794 MJ. This paper documents the development of a computer program which models the energy requirements of a fusion tokamak and compares them to the limitations of a large motor-generator set. The program models the energy requirements of the magnetic confinement coils and also determines the current (Amperes) requirements (as a function of time) reflected to the generator depending on the physics parameters under study for the plasma. This program is used on a daily basis and by optimizing for minimum energy usage, a significant annual cost savings is realized. 3 refs., 2 figs., 1 tab