In this document, the reliability evaluation of line circuits and the development of restoration strategies for ten transmission substations from the most important Colombian power transmission utility (ISA) are presented. There are two types of strategies to restore transmission substations: Fault procedures and contingency plans. The Fault procedures are used to attend non-destructive faults of the switching, control and protection systems on the transmission substation, while contingency plans help to attend destructive faults on power transformers and breakers.By applying the fault procedures and contingency plans, it causes the reduction of the economical consequences of the transmission equipment malfunctioning. The proposed restoration strategies help to accomplish the availability goals imposed by the market regulator and also to maintain the service continuity to the end user.