Cable fault locators can quickly and accurately locate fault points, and their workflow typically follows a precise three-step logic: distance measurement, path tracing, and precise positioning.
Distance Measurement: Determining the approximate distance of the fault point
This is the starting point of positioning work, with the core being to measure the cable length from the test end to the fault point.
Time Domain Reflectometry (TDR): The instrument emits high-speed, low-voltage pulses to the cable. This method is fast and non-destructive, making it the first choice for low-resistance and open-circuit faults.
Bridge Method: Mainly used for high-resistance or flashover faults relative to the ground. This method offers high accuracy but usually requires at least one intact core as a reference.
Path Tracing: Outlining the buried trajectory of the cable
After determining the fault distance, it is necessary to identify the actual underground route of the cable to avoid directional errors during positioning.
Audio Path Method: The signal transmitter of the locator injects an audio current signal of a specific frequency at the starting or remote end of the cable. This signal transmits along the cable conductor and generates a regular alternating electromagnetic field in the surrounding space.
Receiver Tracking: The operator moves on the ground with a handheld electromagnetic field receiver. The receiver delineates the precise buried path of the cable by detecting and amplifying the magnetic field strength signal at specific points above the cable, as indicated by changes in sound volume or meter readings.
Precise Positioning: Locking the exact location of the fault point
On the basis of known distance and path, the fault point is finally locked.
Acoustic-Magnetic Synchronization Method: Suitable for most high-resistance and flashover faults. A high-voltage generator applies periodic high-voltage pulses to the faulty cable, generating a strong discharge arc at the moment of breakdown at the fault point. The discharge produces two key signals:
- Acoustic signal: The explosion sound of discharge, which propagates through the soil to the ground.
- Electromagnetic signal: The strong electromagnetic pulse accompanying the discharge, which propagates almost instantaneously.
Precise Positioning Instrument: The operator uses a positioning instrument equipped with high-sensitivity vibration sensors and electromagnetic field sensors. The instrument captures both acoustic signals and electromagnetic pulse signals simultaneously.
Step Voltage Method: Mainly used for low-resistance grounding faults where the metal sheath or armor of the cable is completely damaged relative to the ground.
Modern cable fault locators are not a single device but a system where three functional units-distance measurement, path tracing, and precise positioning-work in coordination. They integrate multiple physical principles such as time domain reflection, electromagnetic induction, acoustic detection, and step voltage measurement, making fault points buried deep underground or hidden in pipelines detectable. They provide vital technical support for rapid repair and ensure the smooth operation of energy and information arteries. For details about related equipment, please contact sales@celestep.com.
