Measuring method for AC resistance of metal sheath of power cable

Abstract

The invention discloses a method for measuring the alternating current resistance of a metal sheath of a power cable, comprising the following steps: step 1: customizing a test fixture; step 2: processing cable ends; step 3: equipment preheating and calibration; step 4: installing a test fixture , connect the test line; Step 5: Measure and process the data. The measuring method of the invention can be directly used on the finished cable products in a coil, without cutting the cable sample; the measuring equipment is a constant current source, a current testing equipment and a voltage testing equipment, the operation process is simple, and the testing data is accurate; the testing fixture designed by the invention It can be used for the resistance measurement of metal sheaths with different structural forms, and can be adjusted according to the measured object, and has high adaptability; the invention proposes to connect the metal sheath with the external armor layer, and use the armor layer as the return flow of the current. This method can offset the influence of electromagnetic interference on the measurement of the AC resistance of the metal sheath, which has good operability, and has both accuracy, practicability and flexibility.

Description

technical field [0001] The invention relates to the field of parameter measurement of the metal sheath of a power cable, in particular to a method for measuring the AC resistance of the metal sheath of a power cable by using a special test fixture and a small current input method. Angle test to obtain the AC resistance value of the metal sheath of the coiled cable. Background technique [0002] With the acceleration of industrial development and urbanization, underground cables have gradually replaced overhead lines and become the main transmission and distribution lines of my country's power system. Compared with overhead transmission lines, underground cables have the advantages of not affecting the appearance of the city, saving corridor space, and not being affected by the weather environment. [0003] As one of the necessary components of the power cable, the metal sheath is located outside the insulating layer and the insulating shielding layer. Its main functions are...

AI Technical Summary

Problems solved by technology

[0005] The metal sheath is usually a thin layer structure and is made of metal with good conductivity, so its resistance value is small, and the resistance value per unit length is usually only on the order of μΩ / m. It is necessary to accurately measure such a low resistance value is very difficult

Especially when the metal sheath adopts a metal wire or metal strip helically wrapped structure, accurate measurement is more difficult

[0006] For the measurement of the DC resistance of the metal sheath, the bridge method can be used; but for the measurement of the AC resistance of the metal sheath, especially for the coiled cables of production length, there is no special measuring instrument or technical method for reference.

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