BLAVIER TEST PDF

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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Thus, we need to apply less current to this circuit to carry out the experiment. Balance of the bridge is achieved by adjusting the variable resistors. As per the Fig. In this process, mobile shock discharge generators are among the devices used. The figure 4 shows that the circuit connection for finding the fault location when the ground fault occurs and the figure 5 shows that the circuit connections for finding the fault location bllavier the short circuit fault occurs.

An insulation test measures the insulation resistance between conductor and screen; from the periodic measurement of resistance you can derive the absorption properties of the insulating material. Now, the total resistance of the x and g loop is nothing blxvier R 1 — the conductor resistance between sending end and earth by keeping far end open.

But practically, this is not possible. By solving the above three equation and eliminating g and y. If allowed to persist, this can lead to a voltage breakdown. The similar Varley loop uses fixed resistors for RB1 and RB2, and inserts a variable resistor in the faulted leg.

Two balancing are necessary as per the two different circuits. Articles needing additional references from July All articles needing additional references Articles lacking reliable references from November All articles lacking reliable references Articles with multiple maintenance issues.

Cable testing is therefore usually performed first in cable fault location. A Burn Down Instrument has a Voltage Generator connected via Transformer and allows individual control of output voltage and current, a vital balvier for burning down High Impedance Faults. In addition to pulse reflection method and transient method, there are two popular loop tests for finding the location of faults in underground cables. The total resistance of the entire loop of the above circuit is nothing but R 2 — the conductor resistance between sending end and earth by keeping far end earthed.

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One end of the faulted cable is connected through a pair of resistors to the blavifr source. The circuit is shown in the figure at right.

If the switch S is in position 2, then again we need to adjust the variable resistance R to balance the bridge circuit. July Learn how and when to remove this template message.

There would be fractional changes in the bridge arms. November Learn how and when to remove this template message.

In the fault location, the conductor is shorted to ground, because of fault. Thus, the determination of the fault position is not accurate. Impedance changes at the fault location make measuring more difficult. Please help improve this article by adding citations to reliable sources. Then the current circulation through the cable would cause temperature rises due to high voltage or high current.

The conventionally used aid in cable fault testing and location is the cable test van. During the cable test, flash-overs are generated at the weak points in the cable, which can then be localised.

Energy technology Electronic test equipment. Also it is difficult to set the bridge as balance. The necessary boavier of the Murray loop test is shown in figure 2 and 3. So, if L X represents the length between test end blaviet 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.

This expression gives the resistance from the sending end to the fault location. At this position, balvier expressions are as follows; By solving the equation 1 and 2Therefore, the unknown resistance R X is, Varley Loop Test is valid only when the cable sections are uniform throughout the loop.

Cable fault location

Due to this temperature effect, the resistance of the cable would change. If the switch S is in position 1, then we need to adjust the variable resistance R to balance the circuit. So, the total resistance L is equals to the addition of x and y resistances. In cable identification, the faulty cables are identified from the fault-free cables at the already determined site.

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

G is the galvanometer to indicate the balance. The corresponding distance is calculated by known resistance per unit length of the cable. This effects a low-resistance short circuit for a few milliseconds. Tezt is used to determine the fault distance. Let us assume that the new R value as R S2.

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

In 20 years that followed, over fault location vehicles were manufactured, more than half of which were intended for the former USSR. Water penetrates into the cable sheath and contacts the conductors. 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 to the ground.

The current flowing through the cable would cause the temperature effect. This article may rely excessively on sources too closely associated with the subjectpotentially preventing the article from being verifiable and neutral. These methods of cable fault location quickly became established in Western Europe as well. Sheath faults are damage of the cable sheath that allows the surroundings contact with the cable screen. There are predominantly two methods for this. In Murray Loop Testthe fault resistance is fixed and it may not be varied.

The figure 2 shows that the circuit connection for finding the fault location when the ground fault occurs and the figure 3 shows that the circuit connections for finding the fault location when the short circuit blabier occurs. In the transient method, a breakdown is triggered at the cable fault. From Wikipedia, the free encyclopedia.