Author: Noyafa–Cable Tester Manufacturer
What are the tips for using the cable fault tester in the field? Cable identification instrument price Many novices do not know how to use the cable fault tester, but as an electrician, they still need to learn to use the cable fault tester. So what are the skills when using the cable fault tester on-site? The price of cable identification instrument Many novices do not know how to use the cable fault tester, but as an electrician, they still need to learn to use the cable fault tester, so what are the tips for using it in the field? Let's take a look together next! 1, the bridge method. At the test end of the cable line, the conductors of the good phase and the faulty phase are connected to the test instrument as the two bridge arms of the bridge respectively, and the two-phase conductors at the other end are bridged to form a loop. Adjust the bridge, when the bridge is balanced, the product of the corresponding bridge arm resistances is equal, and the resistance value of the cable conductors as the two bridge arms of the bridge is proportional to its length, so the ratio of cable conductor resistance can be converted into the ratio of cable lengths , According to the adjustable resistance and standard resistance value on the bridge, the initial measurement distance of the cable fault point can be obtained.
Mainly used for resistance value in 100kΩThe following single-phase, two-phase, three-phase and phase-to-phase short-circuit (ground) faults. Cable fault testers are generally not suitable for testing high resistance and flashover faults. Because the bridge method mainly calculates the fault distance of the cable manually based on the on-site voltmeter and resistance ratio, its accuracy is not high, and it is not used in the port area.
What are the tips for using the cable fault tester in the field? 2. Pulse method. The pulse method is a method for cable fault location using pulse wave technology. Among them, it is divided into three types: low-voltage pulse reflection method, DC high-voltage flashover test method, and shock high-voltage flashover test method.
The working principle of the low-voltage pulse method is to inject a low-voltage pulse wave at the test end, and the pulse wave propagates along the cable to the fault point to generate reflection and then return to the test instrument, and record the time interval Δt between the transmitted pulse wave and the reflected pulse wave. The wave propagation speed V in the cable can calculate the distance to the fault point. The working principle of the direct-flash method is to apply a DC voltage to the faulty phase of the cable line at the test end of the cable fault tester. When the voltage rises to a certain value, a flashover discharge occurs at the fault point, and the pulse wave and its reflected wave generated by the flashover discharge are used. The time interval Δt of the records together is calculated to calculate the distance to the fault point. Generally speaking, cable faults are divided into high-resistance faults and low-resistance faults. The low-voltage pulse method and the flash-flash method in the pulse method have high accuracy in solving low-resistance and high-resistance cable faults and are not affected by artificial factors, so Become the main application method of cable fault tester.
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