Communication Cable Fault Tester
Recommended by Darui Electric
Product Features
● Combines pulse reflection test method and intelligent bridge test method, capable of testing various types of faults such as open circuits, mixed lines, and poor insulation. The bridge method is only applicable to communication cables.
● Has automatic test function; just press a button, and the fault point can be located.
● Retains manual test function.
● Adopts Chinese menu technology, easy to learn and use.
● Has megohmmeter and ohmmeter functions, capable of testing insulation resistance and loop resistance. This function is only used for communication cables.
● Can save 10 test waveforms, which are not lost after power off, partially replacing the printer function.
● Adopts automatic gain and automatic impedance balancing technology, replacing tedious potentiometer adjustments.
● LCD display has backlight function, allowing testing even at night.
● Uses rechargeable lithium battery with intelligent charging, no need for supervision.
● Small size, light weight, easy to carry.
Product Introduction
It is a high-tech comprehensive cable fault testing product developed with modern microelectronics technology. It has two test methods: pulse reflection and intelligent bridge, suitable for measuring the precise location of faults such as open circuits, mixed lines, ground faults, poor insulation, and poor contact in power cables, local telephone lead-sheathed cables, all-plastic cables, and user drop wires. It is a powerful tool to shorten fault finding time, improve work efficiency, and reduce the labor intensity of line maintenance personnel. Line maintenance personnel can also use it for line engineering acceptance and checking cable electrical characteristics.
Technical Specifications
1. Pulse Reflection Test Method:
● Range 8km, suitable range can be selected based on cable length.
● Test blind zone: 0m
● Test accuracy: 1m when range is less than 2km
8m when range is greater than 2km
● Pulse width: 80ns-10μs automatic adjustment
● Impedance balance automatic adjustment
● Gain adjustment: combination of automatic and manual
2. Intelligent Bridge Test Method (applicable to communication cables):
● Maximum insulation resistance for poor insulation test: 100МΩ
● Test accuracy: ±1%×total cable length
● Maximum cable length testable: 9999m
● Can input in three segments, with wire diameter 0.3mm-0.99mm
● Charging time about 3.5 hours
● Continuous working time after full charge: 5 hours
● Dimensions: 230×150×160
● Weight: 2Kg
Basic Steps:
1. Fault Nature Diagnosis:
Cable faults can be simply classified into the following types:
● Open circuit: One or more core wires of the cable are broken. This type of fault is tested using the pulse method.
● Mixed line: Divided into three types: ground, self-mix, and cross-mix, referring to damage to the insulation layer between the core wire and lead sheath, between the same pair of core wires, and between core wires of different pairs, causing insulation resistance to drop to a very low level (below several hundred to several thousand ohms), or even short circuit, seriously affecting communication quality. This type of fault can be tested first with the pulse method; when the waveform is difficult to identify, switch to the bridge method.
● Poor insulation: The insulation material of the cable core is invaded by water or moisture, causing a decrease in insulation resistance, resulting in poor communication quality or even interruption. This type of fault is similar to self-mix, cross-mix, and ground, but the fault resistance is higher (above several thousand ohms) and the fault is less severe. Usually, if the insulation resistance is less than 2 megohms, it will affect communication quality and needs to be eliminated. This type of fault generally cannot be detected by the pulse method and requires the bridge method.
After a line fault occurs, tools such as a measuring board, megohmmeter, and multimeter should first be used to determine the nature and severity of the line fault, and then an appropriate test method should be selected.
Test personnel understanding the line route and fault conditions helps to quickly determine the fault point. When a cable fault occurs, comprehensively consider the time of the fault, the scope of the fault, the environment of the cable line, the location of joints and manholes, the impact of weather, and possible existing problems.
2. Test Methods:
When the fault resistance is less than several hundred to several thousand ohms, it is called a low-resistance fault; otherwise, it is called poor insulation or high-resistance fault. There is no clear boundary between high and low resistance.
The pulse method is suitable for testing open circuits and low-resistance mixed line faults. Sometimes, more severe poor insulation faults can also be tested with the pulse method. The pulse method is intuitive and simple, does not require coordination at the opposite end, and should be used first during testing.
The bridge method can test high-resistance poor insulation faults, but it requires finding a good wire and coordination at the opposite end, and the test preparation is also cumbersome. It should be used only after confirming that the pulse test method cannot detect the fault.
3. Fault Distance Measurement:
During testing, first disconnect the equipment in the office connected to the faulty pair. Test in the office first to determine the smallest section of the fault point, then go to the site for re-testing to determine the precise location of the fault point.
4. Fault Location:
Based on the instrument test results, compare with drawings and data to mark the specific location of the fault point. If the drawings and data are incomplete or incorrect, estimate the approximate location of the fault point based on the known cable line conditions, then analyze the cause of the fault based on the fault situation and surrounding environment until the fault point is found. For example, if there is a joint within the estimated range, it can be roughly judged that the fault point is inside the joint. The farther the range, the greater the measurement error.
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