Fault recorder acquisition can ensure the integrity and real-time of fault information, and generally does not carry out filtering processing. There are two types of recorded data, alternating signal of instantaneous value of current and voltage and switching value signal reflecting positive and negative jump.

        By analyzing the recorded waveform, the cause of switch tripping can be determined. Therefore, corresponding measures shall be taken to restore the power transmission or outage maintenance of the line, so as to avoid greater losses caused by blind forced transmission, and provide basis for maintenance strategy.

        The recorded switching value action is used to judge whether the protection action is correct, and the cause of incorrect protection action can be found out. For more complex faults, the fault quantity can be calculated through the recorded current and voltage, so as to quantitatively assess the protection.

        Line faults often occur in the power system. The following describes the key points of graphic analysis of three-phase short-circuit fault recording:

       The three-phase current increases and the three-phase voltage decreases; There is no zero sequence current and zero sequence voltage.

       The fault phase voltage is about 80 degrees ahead of the fault phase current; The fault phase to phase voltage is also about 80 degrees ahead of the fault phase to phase current.