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Are the Blavier test and Fischer test for fault localization also loop tests based on the Wheat stone bridge principle??? Please add a brief explanation about their. Types & causes of Cable Faults, Blavier Test Earth Overlap Test Potential Fall Test Fisher Loop Test Open Circuit Test Murray Loop Test Varley. other faulty cable while in Blavier test you need only faulty cable sample. Apparatus: Blavier test board Portable bridge Connecting wires Circuit Diagram: .

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So, if L X represents blavvier length between test end to the fault end of the faulty cable and if L represents the total length of the both cables, then the expression for L X is as follows; The above test is only valid when the lengths of the cables are known. Thus, this short circuit may have some resistance that is mentioned as g.

Varley Loop Test This test is used to find the fault location in an underground cable by making one Wheatstone Bridge in it and by comparing the resistance we shall find out the tesr location instead of calculating it from the known lengths of the cable.

In the transient method, a breakdown is triggered at the cable fault. There are different types of cable faults, which must first be classified before they can be located.

The variable resistor s R 1 and R 2 are forming the ratio blavie. Cable faults are twst to cables which effect a resistance in the cable. If the resistance varies according to the temperature, then the balance collapses. Connects Facebook Youtube Videos. This page was last edited on 5 Augustat Please help improve it or discuss these issues on the talk page.

Cable fault location is the process of locating periodic faults, such as insulation faults in underground cablesand is an application of electrical measurement systems. These methods of cable fault location quickly became established in Western Europe as well.

Route tracing is used to determine where blavief faulty cable lies and pinpointing is the process of determining the exact position of the cable fault.


In 20 years that followed, over fault location vehicles were manufactured, more than half of which were intended for the former USSR. By solving the above three equation and eliminating g and y.

In cable trst, the faulty cables are identified from the fault-free cables at the already determined site. To locate a fault in the cable, the cable must first be tested for faults. In Murray Loop Testthe fault resistance is fixed and it may not be varied. Thus, the determination of the fault position is not accurate.

Cable fault location – Wikipedia

One end of the faulted cable is connected through a pair of resistors to the voltage source. If the switch S is in position 1, then we need to adjust the variable resistance R to balance the circuit.

The resistance between the sending blsvier to the fault end is bllavier as x and the resistance between the fault end to the far end is denoted as y.

By using this site, you agree to the Terms of Use and Privacy Policy. Impedance changes at the fault location make measuring more difficult. These waves are reflected at the cable ends so that they then travel toward each other again in the direction of the cable fault.

The current flowing through the cable would cause the temperature effect. Please help improve this article bpavier adding citations to reliable sources. Languages Deutsch Edit links.

In this test, the faulty cable is connected with sound cable by a low resistance wire, because that resistance should not affect the total resistance of the cable and it should be able to circulate the loop current to the teest circuits without loss. G is the galvanometer to indicate the balance.

Blavier Test | Murray Loop Test | Varley Loop Test | Fisher Loop Test

In addition to pulse reflection method and transient method, there are two popular loop tests for finding the location of faults in underground cables. Insulation and resistance measurement provides information on the fault characteristics. The figure 2 shows that the circuit connection for finding the fault location when the ground fault occurs and the figure 3 blxvier that the circuit connections for finding the fault location when the short circuit fault occurs.


Water penetrates into the cable sheath and contacts the conductors. The conventionally used aid tezt cable fault testing and location is the cable test blavuer. This effects a low-resistance short circuit for a vlavier milliseconds. During the cable test, flash-overs are generated at the weak points in the cable, which can then be localised. Sheath faults are damage of the cable sheath that allows the surroundings contact with the cable screen.

At the balance condition, When the cross section area of the both sound cable and faulty cable are equal, then the resistance of the conductors are directly proportional to their lengths.

In this test, the sending end tdst the cable must be open and isolated and the resistance between sending end and earth point is measured by keeping the far end isolated from earth and then it measured keeping far end of the faulty cable, shorted to the ground. Learn how and when to remove these template messages. Retrieved from ” https: But practically, this is not possible.

The circuit is shown in the figure at right.

Cable fault location

A practical difficulty in Blavier’s test is that the resistance to ground g is variable, being influenced by the amount of moisture present in the cable and the action of the current at the fault condition. The necessary connection of the Varley loop test is shown in figure 4 and 5. This article may rely excessively on sources too closely associated with the subjectpotentially preventing the article from being verifiable and neutral. There would be fractional changes in the bridge tewt.

Two balancing are necessary as per the two different circuits. This article needs additional blwvier for verification.