Substation equipment inspection is necessary for the power industry. With the dramatic increase in the number of substations, unmanned substations are required by the industry. This paper presents SmartGuard, a completely autonomous robotic system that can inspect substation equipment. SmartGuard consists of a robot and a data center. The robot can patrol in a substation and inspect equipment with a visible-light camera and an infrared thermograph. The acquired images and temperature information are analyzed by the data center. The data center can fuse infrared and visible-light images and find abnormal hot spots and abnormal appearance. There are 13 SmartGuards currently serving 12 substations, some of which have been working for more than 2 years. The feedback from the field shows that SmartGuard significantly improves the efficiency and reliability of substation inspection. © 2011 Wiley Periodicals, Inc.