Dr. Chee Wooi Ten of Michigan Technological University looks at the impact of a cyber attack on one or more substations affecting the electric grid from an electrical engineers perspective. Specifically he identifies the physical components in a substation and ranks them in terms of the cost and time to replace. It also is a good and simple primer on how a substation works.
Dr. Ten then shows possible methods for transformer damage by overloading, disrupt switching of breakers and isolators, and entire substation outage.