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What is the cable joint

The cable intermediate joint is a device that connects the cable and the junction box, and is used to connect the cable core or sheath, insulation and sheath to each other. In power system applications, the number of intermediate connections is high. Common intermediate joints have straight-through type (commonly known as “straight-through”) and bend-through type.

The characteristics of the straight-through type are:
(1) Simple structure, small size and light weight;

(2) The construction is convenient, and it can be operated without stripping the outer sheath of the cable during installation;

(3) The price is cheap, but the line loss after laying is large.

The characteristics of the bent-through type are:
(1) The structure is more complicated;

(2) The line loss generated after laying is smaller than that of the straight-through type;

(3) The construction is a little more troublesome;

(4) The price is slightly higher.

In practical engineering, the DC resistance method is generally used to detect the performance of the through. The principle of the DC resistance method is that when a DC voltage is applied to the two electrodes of the through, the resistance value is inversely proportional to the square of the applied voltage.

Therefore, as long as the size of the DC resistance is measured, the conductivity of the through-pass can be known. The DC resistance measurement methods are divided into two categories: direct method and indirect method:
The direct method is to directly measure the DC voltage drop between the two electrodes with a multimeter to determine the pros and cons of the straight-through.

The indirect method is to judge whether it is qualified or not by measuring the alternating current between two electrodes, which is called the AC impedance method or the power frequency withstand voltage test method. The power frequency withstand voltage test method is one of the common and effective methods to judge whether a certain section of conductor is qualified or not. .

When the power frequency voltage of the specified value (usually 50hz) is applied to both ends of the tested conductor, observe whether the tested product has a breakdown phenomenon. Not applicable for this section of wire.


Post time: Jul-02-2022