Abstract: The principle of fault component is widely applied in microcomputer protection. The fault components exist in fault component network. Therefore, it is necessary to establish the fault component network for short circuit fault, and to draw the phasor diagram of current and voltage fault component of fault point. Then according to the concept of symmetrical components, the zero sequence, positive sequence and negative sequence fault components of current and voltage can be obtained, and this is helpful for understanding the microcomputer protection based on the fault component principle.

Key words: fault component, current, voltage, phasor diagram