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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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Views Read Blavied View history. This effects a low-resistance short circuit for a few milliseconds. The corresponding distance is calculated by known resistance per unit length of the cable.

But we should use the known length of the cables in this experiment. There would be fractional changes in the bridge arms.

But practically, this is not possible.

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

The circuit is shown in the figure at right. 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 bridge circuits without loss. Blavir the distance to the fault location is calculated by solving the bridge equation.

The conventionally used aid blavief cable fault testing and location is the cable test van. Thus, we need to apply less current to this circuit to carry out the experiment.

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 tewt action ttest the current at the fault condition.

The waves are unable to pass the fault because of the arc produced by the short circuit, so they are therefore reflected back again as with the pulse reflection method, which due to the burning short circuit results in a reversal blavidr polarity.


These waves are reflected at the cable ends so that they then travel toward each other again in the direction of the cable fault. Pre-location is used to determine the fault distance. Please help improve this article by adding citations to reliable sources.

Cable fault location is the process of locating periodic faults, such as insulation faults in underground cablesand is an application of electrical measurement systems. Thus, this short circuit may have some resistance that is mentioned as g. G is the galvanometer to indicate the balance. The variable resistor s R 1 and R 2 are forming the ratio arms. To perform this test, blavief is necessary to have a sound cable running alongside the faulty cable.

The voltage is interrupted, i.

Languages Deutsch Edit links. Balance of the bridge is achieved by adjusting the variable resistors.

In this test, the sending end of the cable must be open and isolated and the resistance between sending end and earth blavisr 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. If the switch S is in position 2, then again we need to adjust the variable resistance R to balance the bridge circuit.

Cable fault location

The resistance between the sending end to the fault end is mentioned as x and the resistance between the fault end to the far end is denoted as y. One end of the faulted bavier is connected through a pair of resistors to the voltage source.

These methods of cable fault location quickly became established in Western Europe as well. So, the total resistance L is equals to the addition of x and y resistances. There are different types of cable faults, which must first be classified before they can be located. The necessary connection of the Murray loop test is shown in figure 2 and 3.


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Energy technology Electronic test equipment. 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.

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

The bridge is brought to balance by changing the values of R B1 and R B2. During the cable test, flash-overs are generated at the weak points in the cable, which can then be localised. Combination of series and parallel resistances, usually in the form of a wire break. 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 cable identification, the faulty cables are identified from the fault-free cables at the already determined site.

In this process, mobile shock discharge generators are among the devices used. Let us assume that the new R value as R S2.

Cable fault location – Wikipedia

This article has multiple issues. The resistance usually lies in the high-ohmic range. Route tracing is used to determine where the faulty cable lies and pinpointing is the process of determining the exact position of the cable fault.

By using this site, you agree to the Terms of Use and Privacy Policy. Test sets for cable testing can be connected for either bridge technique.