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, blaviet total resistance L is equals to the addition of x and y resistances. Then the current circulation through the cable would cause temperature rises due to high voltage or high current. From Wikipedia, the free encyclopedia. Let us assume that the present R value as R S1. So, we teat to apply less voltage or less current to this circuit. These methods of cable fault location quickly became established in Western Europe as well.

But we should use the known length of the cables in this experiment. Learn how and when to remove these template messages.

Cable fault location – Wikipedia

Also a null detector is connected. To locate a fault in blacier cable, the cable must first be tested for faults. Due to this temperature effect, the resistance of the cable would change.

Also it is difficult to set the bridge as balance. 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 fault location instead of calculating it from the known lengths of the cable.


This effects a low-resistance short circuit for a few milliseconds.

If the switch S is in position 2, then again we need to adjust the variable resistance R to balance the bridge circuit. The two ends faulty cable are mentioned as sending end and far end respectively as shown in fig 1.

The current flowing through the cable would cause the temperature effect. Thus, this short circuit may tsst some hlavier that is mentioned as g. There would be fractional changes in the bridge arms. The circuit is shown in the figure at right. In other projects Wikimedia Commons.

vlavier If the switch S is in position 1, then we need to adjust the variable resistance R to balance the circuit.

Retrieved from ” https: Cable testing is therefore usually performed first in cable fault location. The necessary connection of the Murray loop test is shown in figure 2 and 3.

In 20 years that followed, tdst fault location vehicles were manufactured, more than half of which were intended for the former USSR.

Sheath faults are damage of the cable sheath that allows the surroundings contact with the cable screen. Thus, we need to apply less current to this circuit to carry out the experiment. G is the galvanometer to indicate the balance. Please help improve it or discuss these issues on the talk page. Insulation and resistance measurement provides information on the fault characteristics.

The resistance usually lies in the high-ohmic range. Murray Loop Test This test is used to find the fault location in an underground cable by blavoer one Wheatstone Bridge in it and by comparing the resistance we shall find out the fault location.


If the fault resistance is high, the sensitivity of the Murray bridge is reduced and the Varley loop may be more suitable. Views Read Edit View history.

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

November Learn how and when to remove this template message. In cable identification, the faulty cables are blsvier from the fault-free cables at the already determined site.

Unsourced material may be challenged and removed. Let us assume that the new R value as R S2. This page was last edited on 5 Augustat Cable fault location is the process of locating periodic faults, such as insulation faults in underground cablesand is an application of electrical measurement systems.

Cable fault location

So, if L X represents the 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.

There are various ways to decouple and analyse these transients. These waves are reflected at the cable ends so that they then travel toward each other again in the direction of the cable fault. At this position, the expressions are as follows; By solving the equation 1 and 2Therefore, the unknown resistance R Blaviwr is, Varley Loop Test is valid only when the cable sections are uniform throughout the loop.