The Wired error location is the process of finding periodic errors, such as insulation faults on underground cables, and is an application of electrical measurement systems. In this process, the mobile shock release generator is one of the devices used.
Video Cable fault location
Kesalahan kabel
Wiring error is damage to the cable that affects cable resistance. If allowed to continue, this can cause voltage damage. There are different types of cable errors, which must be classified first before they can be found. Cable insulation plays an important role in this. While impregnated paper cables are particularly susceptible to external chemical and thermal influences, in PE or XLPE cables high-voltage insulated polyethylene conductors are affected, which causes partial damage and cracks that "gnaw" insulation.
Scan errors
The contact between the conductor and the screen produces varying resistance.
Phase errors
Contact between multiple conductors produces varying resistance.
Damage to sheath
Sheath faults are damage to the cable sheath that allows the surrounding contact with the cable display.
Humidity errors
Water penetrates into the cable sheath and contacts the conductor. Impedance changes at the location of the disturbance make measurements more difficult. Resistance is usually located in the low ohmic range.
Disorders
Combination of series and parallel endurance, usually in the form of wire breaks. Voltage disturbed, i.e.? =?.
Maps Cable fault location
Cable Testing
To find the wiring error, the cable must be tested for errors first. Cable testing is therefore usually done first at the cable fault location. During the cable test, flash-overs are generated at weak points in the cable, which can then be localized.
Find cable errors
The steps needed to determine the location of the faults can be divided into several steps.
Error classification
Measurement of isolation and resistance provides information about the characteristics of the disturbance. Insulation tests measure the insulation resistance between the conductor and the screen; from periodic resistance measurements, you can obtain the absorption properties of the insulating material.
Pre-location
Pre-location is used to determine the error distance. There are two main methods for this.
Pulse reflection method
The induced pulse at the end of the cable reaches the cable fault with v/2 velocity and then is reflected back toward the cable's initial end. The elapsed time multiplied by the v/2 diffusion velocity gives the distance to the source of the error. See also: Time-domain reflection .
Temporary method
In the transient method, interference is triggered on the cable fault. It effects short-circuit low resistance for several milliseconds. This in turn produces two waves of travel spreading in the opposite direction. These waves are reflected at the ends of the wires so that they then move toward each other again toward the wiring faults. Waves can not miss errors due to arcs produced by short circuits, so they are reflected back as it does with the pulse reflection method, which is due to the short circuit result burned in reversal of the polarity. There are various ways to separate and analyze these transients.
Route route and show exactly
Route tracking is used to determine where the wrong cable is located and to pinpoint the exact position of the cable fault.
Cable identification
In cable identification, the wrong cable is identified from the error-free cable at a designated location.
Test the loop to find errors in underground cables
In addition to the pulse reflection method and the transient method, there are two popular loop tests for locating faults in underground cables.
Murray round test
Murray loop test uses the principle of wheatstone bridge to find fault. To perform this test, it is necessary to have a sound cable that runs next to the damaged cable. One end of the damaged cable is connected through a pair of resistors to a voltage source. Also the null detector is connected. The other end of the cable is shorted. Circuit shown in the picture on the right. This bridge is brought into equilibrium by changing the values ​​ R B1 and R B2 . Then the distance to the error location is calculated by solving the bridge equation. See also: Murray loop bridge
Varley circle test
Varley similar loop uses fixed resistors for RB1 and RB2, and inserts a variable resistor in the deliberate leg. The test set for cable testing can be connected to the bridge technique. If the fault resistance is high, the sensitivity of the Murray bridge is reduced and the Varley loop may be more suitable.
Conversion error
After a cable fault is identified and placed, it is possible to "burn" using a burning device, in other words to change it from high impedance error to low impedance error. For this, Burn Down Instruments, such as BGG ATG2 Burn Down Transformer or similar devices, can be used. A Burn Down Instrument has a Voltage Generator connected via a Transformer and allows individual control of voltage and output current, an important step to burn High Impedance Faults.
Test van cable
Assistance used conventionally in testing and location of cable interference is testing van cables. The vans are fitted with conventional cable measurement systems to quickly reach the location of any cable faults. In the next 20 years, more than 2,000 vehicles were made, more than half were for the former Soviet Union. This method of cable fault location is quickly becoming established in Western Europe as well.
External links
- Measure the method at the cable interruption location
References
Source of the article : Wikipedia
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