Integrated Cable Fault Positioning & Burn-Through Device

The MOEORW-WLQ61 intelligent bridge integrates cable burn-through function and intelligent bridge fault location function into one portable unit. It adopts a high-voltage constant current source based on switching power supply, delivering stable high voltage and constant current output. The equipment is mainly designed for pre-location of insulation faults on high-voltage, large-cross-section and long-distance complex power cables. It can convert high-resistance cable faults into low-resistance faults via the burn-through module, and accurately pinpoint fault positions with the intelligent bridge module. Except for partial wire breakage faults, this device is applicable to most main insulation faults of high-voltage cables. Different from wave reflection methods, the bridge-based testing has no blind zones, which enables reliable detection for short cables and breakdown points near cable terminals.

The device features a split potential design: the bridge detection module and LCD display operate at high potential, while all control buttons on the front panel work at ground potential and are operated via insulating rods to ensure operational safety. Equipped with customized four-core shielded high-voltage measuring cables and four-terminal resistance measurement technology, it eliminates measurement errors caused by lead resistance. The integrated structure is lightweight and easy to transport for field tests.

This instrument adopts the voltage drop method for fault location. The constant current source injects stable current into the cable core, and the internal circuit measures the voltage drop of the cable conductor between the test terminal and the fault point. Since the conductor resistance is proportional to its length under fixed material and cross-sectional area, the equipment calculates the distance from the test end to the fault point by comparing the measured resistance values and the total resistance of the cable.

Bridge Method & Cross-Section Method

After short-circuiting the faulty core and auxiliary core at the far end of the cable, the device measures the voltage drop of two bridge arms respectively, and calculates the fault distance based on the resistance ratio corresponding to cable length.
 

Intelligent Voltage Method

Conduct two groups of tests with different grounding states at the far end. The first test measures the voltage drop of the full-length cable core, and the second test measures the voltage drop from the test end to the fault point. The fault location is derived from the two sets of measurement data.
 

Burn-through Function

The high-voltage constant current output applies continuous voltage to high-resistance fault points, reducing the fault resistance to form stable low-resistance faults for subsequent accurate location.

1.Ply forms a high-voltage constant current source, realizing steady voltage and current output during long-time operation. The high-voltage output and bridge testing circuits are integrated into a portable trolley plastic cabinet, which balances high voltage performance and portability for field mobile tests.

2.Potential isolation design separates high-potential detection components and ground-potential operating components. All manual operations are implemented through insulating rods, effectively preventing electric shock risks during testing.

3.Matched with customized four-core shielded high-voltage measuring cables. The copper mesh shielding layer is reliably grounded, which suppresses external electromagnetic interference and improves testing stability. The standard measuring cable is 5 m, and optional 15 m or customized 50 m cables are available for different field layouts.

4.A rotating selector switch is configured to switch between burn-through socket and bridge socket. The high-voltage output will be automatically cut off once the switch is lifted, adding a passive safety protection mechanism.

1.Four-terminal resistance measurement technology eliminates the interference of lead wire resistance on test results and guarantees high measurement accuracy throughout the full testing range.
2.No testing blind zones exist, making it suitable for fault detection of short cables and faults near cable terminals where wave reflection methods fail to work effectively.
3.The maximum output current of both burn-through and bridge modules reaches 600 mA. The large current output can quickly burn through high-resistance faults and maintain stable current for high-precision measurement, adapting to complex high-voltage cable systems including GIS terminals and cross-bonding structures.
4.Three optional testing methods (Bridge Method, Cross-Section Method, Intelligent Voltage Method) are provided to match different known cable parameters and field wiring conditions.

1.It supports fault location for complex high-voltage cables without dismantling GIS switches or reconfiguring cross-bonding connections, simplifying on-site operation and improving testing efficiency.
2.Multiple testing methods expand application scenarios: the Intelligent Voltage Method allows thin connecting wires at the far end and supports auxiliary cables with different cross-sections; the Cross-Section Method is applicable when cable material and cross-section data are available.
3.The device is equipped with a complete set of safety interlock functions. The high-voltage circuit cannot be closed if the high-voltage adjustment knob is not at zero position or the selector switch is not pressed down, which avoids misoperation.

1.Pre-location of main insulation faults for various high-voltage power cables, including medium-voltage and high-voltage long-distance cables, large-cross-section cables.
2.Fault detection for complex cable systems with GIS terminals, cross-bonding segments and other special structures.
3.Conversion of high-resistance cable faults to low-resistance faults via burn-through function for subsequent precise fault finding.
4.DC withstand voltage test for power cables to evaluate cable insulation performance.
Note: This device is not recommended for locating outer sheath faults of high-voltage cables. Excessive current may burn the cable sheath, and the measurement accuracy for micro voltage drop below 100 μV is limited, resulting in large positioning errors. If it has to be used, strictly control the output current below 100 mA.

On-site Safety Rules
1.The maximum output voltage of the equipment is 60 kV. At least two operators are required during operation: one is responsible for wiring, and the other conducts inspection. Set up safety guardrails and warning signs around the cable terminals, and arrange a dedicated person for monitoring at the far end of the cable.
2.The main unit must be reliably grounded. Remove rust and paint on the grounding contact surface to ensure low-resistance connection.
3.Before touching high-voltage components after the test, use a discharge rod to fully discharge the test sample, and then connect the grounding wire. For capacitive samples such as cables, do not directly short the high-voltage clips and ground for rapid discharge to prevent damage to the internal circuit.
4.When using bridge-related testing methods, do not adjust the high-voltage adjustment knob arbitrarily during the measurement process.
 

Daily Maintenance
1.After use, rotate the output selector switch to the protective position to prevent dust from entering the high-voltage socket.
2.Store the equipment in a dry and clean environment within the storage temperature range. Avoid severe vibration and extrusion during transportation.
3.For long-time continuous operation, turn the high-voltage adjustment knob back to zero periodically to cool down internal components.
4.Use the supporting test box to calibrate the bridge function regularly. If the deviation exceeds the standard range, stop using the equipment for inspection.