Cable Fault Locator | Multiple Pulse Power Cable Fault Testing Instrument for

The XHGG501E Cable Fault Tester is a dedicated instrument for measuring and analysing the condition and fault distance of power cables. It adopts an industrial-grade 10.1-inch touch all-in-one computer with a simple operation software interface for human-machine interaction testing, and uses industrial-grade integrated circuits and components together with a built-in large-capacity lithium-ion battery for stable, reliable and convenient use.

Combining modern electronic technology with computer technology, the instrument performs signal filtering, acquisition, data processing, graphic display and graphic analysis to complete cable velocity measurement, cable length testing and cable fault distance testing. It is suitable for low-resistance, short-circuit, open-circuit (broken-wire) faults, as well as high-resistance leakage and high-resistance flashover faults, on power cables of different cross-sections, dielectrics and materials, high-frequency coaxial cables, streetlight cables and buried wires.

• 10.1-inch full-color TFT touch display
• Embedded system with a safe, stable and concise display and operation method
• Functions for testing cable velocity, cable length and fault distance
• Fully automatic continuous sampling and real-time waveform capture, fast and accurate
• Automatic test range setting and automatic waveform analysis that displays the test distance
• Full Chinese menu with both touch and encoder key operation, simple, fast and reliable
• Low-voltage pulse method, high-voltage flashover method and multiple-pulse method (8 pulses); smooth waveforms that are very easy to interpret
• In the multiple-pulse method, a pulse coupler is used to display 8 groups of high/low voltage waveform comparison for automatic distance testing, manual analysis and distance measurement
• Powerful data processing for convenient waveform file management and archiving
• Massive waveform storage: stores field waveforms with Chinese naming in sequence; stores more than 8000 low-voltage pulse and high-voltage flashover waveform records and more than 250 multiple-pulse waveform records; waveform files can be transferred to PC software via USB for management and analysis
• Ultra-high-brightness LED backlight up to 280 nit with 1024 × 600 resolution, convenient for operation under direct sunlight
• Built-in large-capacity lithium battery pack with fast charging support, so testing is possible in environments without mains power
• Protective enclosure rated not lower than IP54

• Open-circuit fault: the insulation is normal but, due to conductor problems, voltage cannot be transmitted normally — for example a conductor or ground wire that is nearly but not fully broken, a large line resistance at one point of the core, or a broken core.
• Low-resistance fault: an insulation medium is damaged and a phase-to-phase or phase-to-ground fault can be measured directly with the low-voltage pulse method; the resistance is usually below several hundred ohms. If the resistance is zero, it is called a short-circuit fault.
• Leakage high-resistance fault: the insulation medium is damaged and a fixed resistance channel has formed, but the fault cannot be measured directly with the low-voltage pulse method; the resistance is usually above several hundred ohms.
• Flashover high-resistance fault: within the pre-test voltage range, when the pre-test voltage reaches a certain value the leakage current suddenly increases greatly; the cable insulation is damaged but no fixed resistance channel has formed.

1. Analyse the nature of the cable fault and understand the voltage level and insulation medium of the faulty cable.
2. Use the low-voltage pulse method to test the length of all phase conductors of the faulty cable and calibrate the electric-wave transmission velocity of the cable.
3. Select a suitable test method and carry out rough measurement of the cable fault with the instrument.
4. Carry out precise measurement of the fault point, including finding the route and depth of buried cables and precisely locating the fault point.
5. Carry out error analysis of the cable fault test results (measurement error, transmission velocity error, interpretation error and instrument error).

When an electric wave travels in a transmission line and the line is not uniform, the characteristic impedance at a point changes; after the wave reaches that point it not only continues forward but also produces a wave travelling in the opposite direction back to the test end. This reverse-travelling wave is called the reflected wave, and the phenomenon is called reflection. The incident wave and the reflected wave together are called travelling waves. At a short-circuit point the polarity of the echo is opposite to that of the transmitted pulse, whereas at an open-circuit point (including the cable terminal) the echo has the same polarity as the transmitted pulse. Low-resistance and open-circuit faults can therefore be located very easily with the low-voltage pulse method according to the echo polarity. For high-resistance faults, the high-voltage flashover method is used: a high-voltage pulse signal source (for leakage high-resistance faults) or a DC high-voltage source (for flashover high-resistance faults) causes the fault point to flash over and discharge, producing a reflected signal that is detected at the test end. The signal then passes through a high-speed A/D converter and the computer control system, where the analogue signal is converted to a digital signal, stored, digitally processed, displayed as a test waveform and analysed — completing the rough measurement of the fault distance.

A low-voltage pulse signal is applied to the cable under test; the pulse is reflected at the fault point, the reflected signal is processed and presented as a waveform, and the rough fault distance is judged by analysing the reflected waveform.

• Direct flashover method: mainly used to test flashover high-resistance faults of power cables. A DC high-voltage source applies DC voltage to the faulty cable; when the DC voltage reaches a certain value the fault point suddenly flashes over and discharges, and the DC high voltage produces a reflected signal at the fault point which is received by a dedicated sampler and transmitted to the instrument for processing and analysis.
• Impulse flashover method (universal method): mainly used to test leakage high-resistance faults of power cables. A high-voltage pulse signal source applies a high-voltage pulse signal to the faulty cable; the pulse passes through the fault point, the fault point flashes over and discharges and produces a reflected signal, which is received by the dedicated sampler and transmitted to the instrument for processing and analysis.

As a cable fault test system using the multiple-pulse method, the instrument set includes an integrated high-voltage generator that produces a single impulse high voltage, a multiple-pulse generator, a multiple-pulse automatic trigger device and test waveform analysis software. The multiple-pulse generator guides the instantaneous impulse high-voltage pulse produced by the high-voltage unit onto the faulty phase of the cable, ensuring the fault point is fully broken down and extending the arc duration after breakdown. The automatic trigger device then immediately sends several low-voltage test pulses to the faulty cable. The first eight test pulses make use of the short-circuit characteristic at the instant the cable arc breaks down to form eight fault reflection pulses; after the fault point arc is extinguished, a further eight test pulses are sent to measure the open-circuit reflection waveform, forming eight groups of secondary pulse waveforms. The multiple-pulse method lets the low-voltage test pulses effectively avoid the large cosine oscillation interference that occurs at the instant of impulse high voltage, so that clear standard waveforms similar to a short-circuit fault echo can be obtained during the relatively stable period of the fault-point short-circuit arc — greatly simplifying the test procedure.

The instrument set consists of the cable fault tester (which uses the low-voltage pulse method, high-voltage flashover method and multiple-pulse method to test and analyse cables), a coupler (used in the multiple-pulse method, optional), a 1.5 m single-Q output line (connects the tester to the cable under test in the low-voltage pulse method), a 2 m double-Q input line (connects the tester to the sampler in the high-voltage flashover method), a sampler (receives the high-voltage signal reflected at the sampling ground in the high-voltage flashover method), a 1.8 m power line (charging cable), coupler high-voltage line A (connects the coupler to the cable under test in the multiple-pulse method; insert / pull only, do not twist), coupler high-voltage line B (connects the coupler to the high-voltage pulse signal source in the multiple-pulse method; insert / pull only, do not twist), a 2.5 m ground line (coupler grounding line) and a USB line (for importing waveform files to a PC).

1. In the main interface function setting area, select the medium velocity, set the mode to low-voltage pulse and select a suitable test range; if automatic range judgement is needed, click "Automatic Measurement".
2. After setting the parameters, click "Sample"; the screen enters the test and waveform processing interface and the instrument automatically performs low-voltage pulse sampling. Adjust "Displacement" and "Amplitude" as needed and observe the echo, so that the waveform is not clipped at the upper or lower limit, until the echo amplitude is suitable for analysis.
3. Press "Hold" to stop sampling. Use the overall waveform control area to move the waveform left and right and to compress it until the waveform is in the best state for analysis, then use the cursor to set the distance and interpret the waveform.
4. Click "File Processing" to save the current waveform for later viewing and comparison.

1. Select the medium velocity, set the mode to high-voltage flashover and select a suitable test range; click "Automatic Measurement" if automatic range judgement is needed.
2. After setting the parameters, click "Sample". After the reflected signal is received by the dedicated sampler, adjust "Displacement" and "Amplitude" as needed and observe the echo, so that the waveform is not clipped at the upper or lower limit, until the echo amplitude is suitable for analysis.
3. Press "Hold" to stop sampling; move and compress the waveform until it is in the best state for analysis, then use the cursor to set the distance and interpret the waveform.
4. Click "File Processing" to save the current waveform.

1. Select the medium velocity, set the mode to multiple-pulse and select a suitable test range; click "Automatic Measurement" if automatic range judgement is needed.
2. After setting the parameters, click "Sample". After the reflected signal is received by the dedicated coupler, adjust "Displacement" and "Amplitude" as needed until the echo amplitude is suitable for analysis.
3. The waveform display area shows waveform group 4 by default; if that group is not satisfactory or cannot be analysed, click the "1–8" analog keys on the left of the screen to display the corresponding multiple-pulse group for analysis.
4. During waveform analysis, the automatic measurement key can be pressed in either the sampling or hold state to set the distance; or, in the hold state, press the cursor key for manual analysis, and use "Waveform Expansion / Compression" to expand or compress the waveform.
5. Move the cursor to interpret the fault distance, aligning the cursor accurately with the leading edge of the transmitted pulse and of the fault echo pulse for precise reading.
6. Click "File Processing" to save the current waveform.

After testing, previously saved records can be viewed by clicking "File Processing" in the upper-right of the screen, selecting the file name and clicking "Open". To archive or print waveform files on a PC, use the "Export" function: install the waveform file management software on the PC, connect the instrument to the PC with a USB line, install the provided driver, restart the instrument, open the cable fault browsing software, click "Scan" under "Test Type", select the serial port assigned by the PC and click "Open" to complete the communication setup. Then select the waveform file to be exported in the instrument's "File Processing" interface and click "Export"; the corresponding waveform will be displayed on the PC, and the "Save" button can be used to save it, while "Waveform Print" saves the waveform file as an image for printing.

• Read this manual in detail and follow the relevant precautions. Do not subject the instrument to severe impact, and do not shut it down illegally.
• Connect the test lines correctly, especially the ground line and the high-voltage line.
• When wiring for the high-voltage flashover method or the multiple-pulse method, it is strictly forbidden to select the low-voltage pulse method in the instrument software.
• It is strictly forbidden to carry out high-voltage flashover or multiple-pulse sampling while the instrument is charging.
• Charge the instrument when the battery is low. The instrument is dual-purpose AC / DC with a built-in large-capacity lithium battery; if it is not used for a long time, charge it about once every 2 months to prevent the battery from self-discharging and being damaged.
• Before use, check whether the battery is sufficient to prevent illegal shutdown or repeated restart of the industrial computer due to low battery, which could damage system files (charging for 1 hour gives about 2.5 hours of standby; charging for 2 hours fills the battery from zero).
• When only the low-voltage pulse method is used, the instrument can be powered by AC 220 V; it is strictly forbidden to connect AC 220 V for high-voltage flashover or multiple-pulse sampling tests.
• The instrument is highly precise electronic equipment and must not be disassembled by non-professionals. Handle it gently during transport and never operate it roughly or subject it to impact.
• If the instrument behaves abnormally, contact the dealer or the company promptly. Damage caused by human factors will void the instrument warranty.
• When testing with the low-voltage pulse method, always confirm that the cable itself is not carrying stored charge.
• Note: never carry out high-voltage flashover sampling while the instrument is powered by AC 220 V, and never connect the sampler while the software is in low-voltage pulse mode for high-voltage sampling.

The instrument comes with a one-year free warranty for quality problems from the date of purchase, and lifetime repair and technical service are provided. If you find that the instrument is not operating normally or a fault occurs, please contact us so that we can arrange the most convenient and effective solution for you.