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First, the first end of the cable to measure the capacitance current of each core line (should keep the voltage to maintain the same) Ia, Ib, Ic value.

（2）在電纜的末端再測量每相芯線的電容電流Ia’、Ib’、Ic’的數(shù)值，以核對完好芯線與斷線芯線的比容之比，初步可判斷出斷線距離近似點。JBYH電機引接線

(2) at the end of the cable to measure each phase conductor capacitance current of Ia ', Ib' and Ic 'value, to check the volume of intact core wire and core wire breakage ratio, initial can determine the approximate point line distance.JBYH電機引接線

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(3) according to the capacitance formula C = 1/2 PI fU shows that the voltage at the frequencies of U, C and I f constant is proportional to the frequency of the voltage; because f (frequency) constant measurement as long as the applied voltage constant, capacitive current ratio for capacitance ratio. The length of the cable is L, the distance between the core and the line break point is Ia/Ic, then L/x = x, x = (Ic/Ia) L. In the process of measurement, as long as the voltage is guaranteed, the current meter readings are accurate, the total length of the cable is accurate, and the measurement error is relatively small.

4, zero potential method. The zero potential method, which is applied to the cable core line with short length, is suitable for the fault of the cable with short length. The method is simple and accurate, and does not require precise instrument and complicated calculation. The measuring principle is as follows: the cable fault core wire is parallel to the length of the equal length, and is equal to the power supply at both ends of the two parallel resistors when the E is pressed at both ends. At this point, the electric potential difference between any point on the resistance wire and the corresponding point on the other resistance wire is bound to be zero. On the other hand, the potential difference between the zero points must corresponding points, because the negative microvoltmeter grounding, and so the cable fault point microvoltmeter, equipotential, when the cathode in comparison to conducting showing the value of zero point and fault point potential, namely fault point correspondences.