Cable fault detection method and portable cable fault detector

The invention discloses a cable fault detection method and a portable cable fault detector, and the method comprises the following steps: S1, enabling metal sheaths at the two ends of a cable line to be grounded, dismounting an interconnection part of an interconnection intermediate box, and enabling the metal sheaths at the two ends of each phase of cable head to be short-circuited; s2, sending a low-voltage pulse once, and recording a reflection waveform; s3, releasing the high-voltage pulse, and enabling the cable fault point to be instantaneously broken down to form a high-voltage fault; s4, sending another low-voltage pulse within the duration of the high-voltage fault of the fault point, and recording the reflection waveform of the fault point; and S5, comparing the two reflection waveforms to obtain the position of the fault point. According to the invention, the fault point is measured through the improved secondary pulse method, the distance measurement error is small, and the positioning precision m