The design criteria of the 115/22 kV substation construction are shown in Table XI. The project periods is estimated at 15 years. The income tax rate and the minimum loan rate are set with 30% and 6.5%, respectively. The preventive maintenance cost of AIS type and GIS type are provided by standard supplier handbook. The operating cost of substation is estimated at 204,000 Baht/year. To study the economic value of construction 115/22 kV substation, the electronic industries with peak demand 6 MW are demonstrated to assess the investment benefits for both AIS and GIS. In addition, the investment analysis is considered both cases of considering and without considering the outage cost. The study results of
115/22 kV substation construction with peak demand 6 MW
are shown in Table XII.