The power system analysis studies serve as the basis for ensuring reliability, improving system performance and power quality, reducing operating costs, and providing a reliable supply power during system operation. Thus, this paper presents a case study for designing power supply system for an offshore platform which will include load flow study, short circuit study and transient stability study. The studies mentioned will be conducted through simulation by using Electrical Design Software Analysis, EDSA. This paper also outlines the system design requirements for designing power supply system, power system configuration and also power operating philosophy for an offshore platform. The results obtained are acceptable and confirms with the standards used by the electrical consultants. ©2010 IEEE.