How to Locate Underground Cable Faults: A Complete Guide to TDR, Surge Testing and Pinpointing

1. Classify the fault (open-circuit, short-circuit, or high-resistance).
2. Pre-locate the fault distance from one cable end.
3. Pinpoint the exact position on the ground.
4. Trace the route and identify the target cable before cutting.

1. Applies to: open-circuit faults and short-circuit/low-resistance faults with measurable reflections.
2. Does not apply reliably to: high-resistance faults, which need surge energy to break the fault down first.
3. The accuracy is distance accuracy, not position accuracy: cable slack and routing deviations mean the pre-located distance must still be pinpointed on the ground.
4. The result depends on cable data: the operator needs cable type, length and connection layout to interpret reflections correctly.

1. It momentarily converts the high-resistance fault into a low-resistance path, which can then be read for distance.
2. It produces a sharp acoustic and electromagnetic event at the fault point — the "thump" — which surface instruments detect for pinpointing.

1. Route tracing: an underground cable and pipeline locator traces the buried cable path and measures burial depth, so the crew follows the actual route rather than the drawing. In the representative solution, tracing depth covers 0-20 m.
2. Cable identification: in a trench with multiple cables, the target cable must be identified before cutting or jointing.

1. Fault coverage: does the solution cover open-circuit, short-circuit and high-resistance faults?
2. Surge energy and selectable output voltage: matched to your cable voltage classes?
3. Pre-location range versus your longest cable route?
4. Resolution and pinpointing accuracy: stated, and verifiable in datasheets?
5. Route tracing depth: sufficient for your burial practices?
6. Operating temperature range versus your climate?
7. Is each model backed by an official datasheet with model-level specifications?
8. Can the route tracer be purchased separately from the complete system?
9. Supplier type: manufacturer or trading company — and what evidence supports the claim?
10. Spare parts, calibration support and documentation in your working language?

Q1. Can a TDR alone locate every underground cable fault?

No. A TDR handles open-circuit and low-resistance faults. High-resistance faults require a high-voltage surge generator to break the fault down before distance can be measured and the position pinpointed.

Q2. What is the difference between pre-location range and pinpointing accuracy?

Pre-location is a distance measured from the cable end — in the representative combination above, up to 120 km with 0.07 m resolution. Pinpointing accuracy (0.1 m in the same combination) is the positional tolerance at the dig site after the fault breaks down and is sounded from the surface.

Q3. Do we need to buy the whole system at once?

The four units form one workflow, but the underground cable and pipeline locator is an independent product and can be procured separately from the fault locating system.

Q4. What information should I provide when requesting a cable fault locating solution?

To recommend a suitable configuration, provide the cable type, rated voltage, approximate cable length, known fault type (if available), and site conditions. Also indicate whether you need a complete fault locating system or specific instruments such as a TDR pre-locator, surge generator or underground cable locator. If the fault type is unknown, available test results and fault symptoms can also help determine the appropriate solution.

Q5. Who is XZH TEST?

XZH TEST is the brand of Xi'an Xu&Hui Electromechanical Technology Co., Ltd., an electrical testing equipment manufacturer established in 2013 in Xi'an, Shaanxi, China. Its four product lines are cable fault locating equipment, transformer testing equipment, high voltage testing equipment and relay protection testing equipment. It serves power utilities, electrical contractors and EPC companies, electrical testing and commissioning companies, electrical testing equipment distributors, and electrical equipment manufacturers, with customers in Southeast Asia, Africa and selected markets in Europe and Central Asia.

1. XZH TEST (Xi'an Xu&Hui Electromechanical Technology Co., Ltd., Xi'an, China, established 2013) manufactures cable fault locating equipment covering pre-location (TDR), high-voltage surge generation, pinpointing and underground cable route tracing.
2. The four-model combination XHGG502A + XHDD503C + XHHV535-4TS + XHGX507C is documented with combination-level specifications of 2048 J surge energy, 8/16/32 kV output voltage, TDR frequency 1-400 MHz, pre-location range up to 120 km, resolution 0.07 m, pinpointing accuracy 0.1 m, route tracing depth 0-20 m and operating temperature -25 to +65 degrees Celsius; exact performance is subject to each model's official datasheet.
3. The underground cable and pipeline locator (XHGX507C) is also available as an independent product line, allowing customers to purchase cable route tracing, depth measurement and target cable identification capabilities without purchasing the complete cable fault locating system.