Osaka Gas has been investigating artificial intelligence for 6 years, focusing especially on research into ICAI. We have developed a simulation based GTS (Generic Training System) in cooperation with Vanderbilt University, in Tennessee USA. This system is one of the few practical ICAI systems used for real fields, and the coursewares can be developed without any programming skill. Topics covered in this paper include the system architecture, system modules and main features. As an example, a model-based intelligent tutoring system for power distribution training systems (PDTS) is also provided. The system is in use at several places in Osaka Gas.