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Locating Cable Faults - The Murray Fisher method

FIGURE 1 shows a Wheatstone Bridge connection used to determine the location of a fault on a cable in which two cores are of different cross-sectional area (the Murray Fisher method). Ignoring test lead resistance, show that:

a) For the first reading position, the resistance to the fault, Rx, is given by
Rx = Rb1 / Ra1 + Rb1 (Rc1 + Rc2)

b) For the second reading position and substituting for Rc1, the distance to the fault, x, is given by:
x = (Rb1 / Ra1 + Rb1)(Ra2 + Rb2 / Rb2)(L)
x = Rb1 / Rb2 (Ra2 + Rb2 / Ra1 + Rb1) L

C) If the cable tested is 100m in length, Ra1 is 1,5 ohms, Rb1 is 1.0 ohm and Ra2 / Rb2 = 0.8, calculate the distance to the fault.

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IGURE 1 shows a Wheatstone Bridge connection used to determine the location of a fault on a cable in which two cores are of different cross-sectional area (the Murray Fisher method). Ignoring test lead resistance, show that:

a) For the first reading position, the resistance to the fault, Rx, is given by
Rx = Rb1 / Ra1 + Rb1 (Rc1 + Rc2)

Condition for the bridge to be in equilibrium (no ...

Solution Summary

The expert locates cable faults for the Murray Fisher Methods.

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