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

Cable faults are damage to cables which effect a resistance in the cable. The text is interrupted, i. Fisher Loop Test In this Fisher Loop Testthere must be two healthy sound cables which must have the same length and same cross sectional area as the faulty cable. The necessary connection of the Murray loop test is shown in figure 2 and 3.

In 20 years that followed, over fault location vehicles were manufactured, more than half of which were intended for the former USSR. Cable fault location is the process of locating periodic faults, such as insulation faults in underground cablesand is an application of electrical measurement systems. 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 of polarity.

Then the distance to the fault location is calculated by solving the bridge equation. Then the current circulation through the cable would cause temperature rises due to high voltage or high current. The circuit is shown in the figure at right. The insulation of the cable plays a significant role in this. The similar Varley loop uses fixed resistors for RB1 and RB2, and inserts a variable resistor in the faulted leg.


In Murray Loop Testthe fault resistance is fixed and it may not be varied. The conventionally used aid in cable fault testing and location is the cable test van. The corresponding distance is calculated by known resistance per unit length of the cable. Thus, the determination of the fault position is not accurate.

Two balancing are necessary as per the two different circuits.

Cable fault location

Thus, we need to apply less current to this circuit to carry out the experiment. G is the galvanometer to indicate the balance.

So, we need to apply less voltage blwvier less current to this circuit. The variable resistor s R 1 and R 2 are forming the ratio arms. In this test, the sending end of 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 rest the ground.

This article needs additional citations for verification. One end of the faulted cable is connected through a pair of resistors to the voltage source. The other end of the cable is shorted. 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.

If the resistance varies according to the temperature, then the balance collapses.


Suppose, we get, resistance values R 1 and R 2 blafier these two said measurements respectively. Insulation and resistance measurement provides information on the fault characteristics.

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

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Thus, this short circuit may have some resistance that is mentioned as g. Languages Deutsch Edit links.

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

Sheath faults are damage of the cable sheath that b,avier the surroundings contact with the cable screen. The figure 4 shows that the circuit connection for finding blavied fault location when the ground fault occurs and the figure 5 shows that the circuit connections for finding the fault location when the short circuit fault occurs. If the switch S is in position 1, then we need to adjust the variable resistance R to balance the circuit. Please help improve it or discuss these issues on the talk page.

There are predominantly two methods for this. But we should use the known length of the cables trst this experiment. This page was last edited on 5 Augustat In this process, mobile shock discharge generators are among the devices used.

If the switch S is in position 2, then again we need to adjust the variable resistance R to balance the bridge circuit.