Talking about the Causes of Faults in Cross-connected Cable Joints

Because of the different operating modes and conditions of the cable joints, the different levels of the technical level of the construction workers, and the uneven quality of the cable accessories, the causes of breakdown of the cross-connected cable joints are also different. To this end, Yanzhou Mining (Group) Co., Ltd. carried out analysis and research on the causes of faults in the cross-connected cable joints.

(1) The process of making cable joints is poor.

1 The contact fittings are not well handled. Due to production or storage conditions, impurities, burrs, and oxide layers are present on the terminals or the inner wall of the connecting pipe. This is a defect that is not taken seriously by people, but it has a serious impact on the quality of the conductor connection. In particular, the aluminum surface is extremely easy to produce a hard and insulating aluminum oxide film, and the aluminum conductor connection is much more stringent than the copper conductor connection technology.

2 conductor damage. The crosslinked insulation layer has a high strength and is difficult to strip. When the construction worker circumcises, he or she must use an electrician's knife to cut it to the right, sometimes cutting the deep marks with a hacksaw, often causing the conductor to be damaged.

3 cores are not in place. When the conductor is connected, the length of insulation stripping requires that the depth of the crimped metal fittings be 5mm deep. However, because the product hole depth is not standard, the stripping length is likely to be insufficient, or the voids will be formed at the end of the wire due to the crimping during crimping. As a result, contact resistance increases and heat generation increases.

(2) The pressure is not enough.

Nowadays, relevant information in the production of jointing processes and standard drawings only mentions the number of pressure holes at each end when the cable is connected. The crimping area and the crimping depth are not described in detail. The construction personnel pressed the number of the pressure holes as required, but the effect was not able to be achieved. determine. The main reasons for the lack of conductor connection pressure are as follows:

1 pressure equipment pressure is insufficient. Crimping equipment manufacturers more, but there is no uniform standard, and some mechanical pressure clamp pressure is narrow and the pressure is not consistent with the upper and lower pressure die after the receipt of the position, and some implementation of foreign standards, and the domestic conductor of the nominal section does not meet.

2 large gaps for connecting hardware. The connection hardware used for most of the cross-linked cable connectors is also the terminal and crimping pipe produced from the oil-paper cable in accordance with the fan-type wire. Theoretically speaking, the effective cross-section of the round and fan-shaped cores is the same, but from the actual operation shows that the two crimping effect is very different. As the cross-linked cable conductor is a tightly wound round wire core, there is a large gap with the inner diameter of the commonly used metal fittings, and after the crimping, a sufficient compressive force is not achieved. The contact resistance is inversely proportional to the applied pressure, thus resulting in an increase in resistance. (3) Insufficient cross-section of the connection hardware is a very important cause of cross-link cable connector heating.

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