Electrical energy is already a staple for residents in Indonesia. Every year Indonesia experienced an increase in population and the number of the economy so that the amount of energy consumption of electricity or electrical load needs will continue to increase. The increased needs of the burden will affect the capacity of transformer capability in serving the load. This research was conducted to find out the capabilities of the transformer Substation at 150 kV Mains Ungaran until 2032. The methods used in the estimate the capabilities of the transformer that is linear regression method double, while data used the data i.e. peak load year 2013 to 2017 on Stem 150 kV Substation Ungaran. Other data required in performing data processing namely population growth and GDP data in the BPS Kabupaten Semarang. Forecasting the growth of the load on the transformer 2 GI 150 kV ungaran is still in a State of mild load for 15 years, whereas in transformer 3 is already in a State of heavy loads of up to 15 years.