Sharing of fault location methods for buried deep cables

 

Sharing of fault location methods for buried deep cables

What constitutes a large burial depth?

    Cables with a burial depth exceeding 1.5 meters can be referred to as large burial depth. When laying cables normally, it is rare to bury them too deep. Generally, cables may be backfilled and raised later on, resulting in an increase in burial depth.

Will a large burial depth affect testing?

When testing cables with large burial depths, the depth of cable laying is too high, which affects ground signal reception. When testing, a high-voltage generator with high discharge energy should be selected, and the sensitivity of the instrument for precise positioning must also be high.

How to test for this type of malfunction?

When encountering a large buried cable fault. After testing the distance, it is recommended to observe the burial depth of the cable while measuring the cable path (note: a cable path meter with depth measurement function needs to be selected at this time). If there is a significant change in burial depth, record it at any time. For accurate positioning, it is recommended to use a positioning instrument with time difference. If the grounding is severe, it is recommended to use the step voltage method for precise positioning.

Test site for faults in buried deep cables (Part 1)

Location: Shaanxi Steel Structure Factory, Lintong District;

Cable type 10kV cross-linked cable fault location;

Cable burial method: direct burial on land for 6 meters;

Fault type: metal short circuit and grounding;

Instruments used: QLD-301 intelligent cable fault rangefinder, QLD8000 cable routing instrument, QLD-M30 integrated high-voltage generator for cable fault testing, QLD-D30 multifunctional cable fault precise locator.

Testing process sharing:

（1） Understand the on-site situation

Qilida's on-site technical engineer Mi Gong arrived at the cable fault testing site with testing equipment. The cable in the factory is a 10kV cross-linked cable that has been buried for more than ten years. During this period, road construction and other constructions have undergone secondary backfilling. The specific location and burial depth of the cable are not clear.

（2） Determine the nature of the fault

The QLD-M30 cable fault test integrated high-voltage generator was used for voltage withstand testing, and leakage current was found. The insulation meter was used to test the resistance value, which was almost 0M ohms, indicating that the cable was a ground fault.

 （3） Test cable fault distance

    The low voltage pulse method of QLD-301 intelligent cable fault rangefinder is used to measure the total distance of 1200 meters. The QLD-301 intelligent cable fault rangefinder is combined with QLD-M30 cable fault testing integrated high voltage generator to measure the distance of the cable using high voltage flashing method, which is 900 meters.

 

（4） Cable path search and precise positioning of fault location

Use a ruler and QLD8000 cable routing tool to locate the cable path from the opposite end, mark the path and burial depth near 300 meters, click one button depth measurement, and the cable burial depth will be displayed as 6 meters. The QLD-D30 cable fault locator is used to accurately locate near the fault point, resulting in a deep burial depth and low sound during impact discharge. By combining sound with waveform, the location of the fault point can be clearly determined. Coordinate the excavator on site for excavation, and the fault point is located directly below the location after excavating the cable.

Test Summary

The on-site cable burial was relatively deep and difficult to locate. After more than 2 hours, the plumber successfully found the fault point. When conducting on-site testing for cable faults with large burial depths, it is required that the high-voltage generator has high impact discharge energy, the locator has high sensitivity, strong signal receiving ability, and the path analyzer must have direct reading testing function (convenient for real-time detection of cable burial depth).

 

Shaanxi Qilida Electronic Technology Co., Ltd. has always adhered to the concept of manufacturing high-quality pipeline (cable) fault testers, making cable fault testing simpler, more efficient, and more accurate! To provide better service for customers at home and abroad, when buying pipeline (cable) detection equipment, look for Qilida.

 

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