1.1 Function and Numbered Principle of Secondary Equipment+ 1.2 Wiring and Working Mechanism of Microcomputer Protection Cabinet+ 1.3 Set Screen Principle of Protection Cabinet+ 1.4 Hardware Principle of Microcomputer Protection Device+ 2.1 Microcomputer Protection Software Principle+ 2.2 Operation Method of Protective Device+ 3.1 TA, TV disconnection Self-Check Principle+ 3.2 Current Transformers and Their Configure Wiring+