# Varly loop test for locating underground cable fault

Varly loop test is a test by which we can locate the earth fault or short circuit fault in the underground cable. It is slightly different from Murry loop test in this the ratio arms P & Q are fixed resistance and a variable resistance (s) is connected to the test end of the faulty cable. The connection diagram for locating the earth fault is shown in fig. The key K2 is first connected to position 1, now the variable resistance S is varied till the galvanometer shows zero deflection. Let, the resistance of the variable resistance is S1 when galvanometer shows zero deflection. Then we can write Now the switch K2 is position 2. Then the variable resistance S is varied till the galvanometer shows zero deflection. Let , the resistance of the variable resistance is S2 ,when galvanometer shows zero deflection. The value of P,Q,S1 and S2 are known , we can easily get the value of loop resistance. If the resistance of the cable per meter length is r,
Then the distance of fault form the test end is We can easily located the short circuit fault of the under ground cable as same process as above.The circuit diagram of short circuit fault is given below:- ## Recent Post Multiple Choice Question (MCQ) of Electronics page-17:241. Which of the following statement is true? a) The saturation voltage VCF of silicon transistor is more than germanium transistor. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. c) The saturation voltage VCE for silicon transistor is same as that for germanium. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor.Read more... Multiple Choice Question (MCQ) of Electronics page-16:226. Which of the following statement is correct? a) Inner electrons are always present in the semiconductor. b) Bound electrons are always present in the semiconductor. c) Free electrons are always present in the semiconductor. d) Inner and bound electrons are always present in the semiconductor.Read more... Multiple Choice Question (MCQ) of Electronics page-15:211. The materials whose electrical conductivity is usually less than 1 × 106 mho/m are a) Semiconductors b) Conductors c) Insulators d) AlloysRead more... Multiple Choice Question (MCQ) of Electronics page-14:196. In which of the following device the base resistors are not added in the package but added externally? a) UJT b) CUJT c) PUT d) None of the aboveRead more... Multiple Choice Question (MCQ) of Electronics page-13:181. The conduction in JEFT is always by the a) Majority carriers b) Minority carriers c) Holes d) Electrons e) Holes and electrons simultaneouslyRead more...

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