Installation instructions for special fasteners for electrical contacts

Overheating of electrical contacts is an old and difficult problem that has existed for decades in the power system of power generation, power supply, and electricity consumption. The overheating of electrical contacts must be raised to the height of safety in production. It is necessary to take it seriously, and solve it all at once! The guiding ideology of head overheating).

Special fasteners for electrical contacts is a book "Electrical Contacts" written by Ren Yi, a senior technician of substation maintenance, with 40 years of practical experience in production. According to the "Four Principles" in the book to solve the overheating of electrical contacts: 1. The effective current-carrying cross-sectional area is the basis for the overheating of the electrical contact; 2. The pressure of the contact is the key to overheating; 3. The electrical contact is very resistant to corrosion. Important; Fourth, the fatigue problem of electrical contact materials (including fasteners) cannot be ignored; and the combination of patented technology "Overheating electrical contacts and fasteners" (ZL01214234.4) is specially tailored for the electrical connection of power systems. Made". Instead of using mechanical standard bolts to connect electrical contacts in the power system, years of practice have shown that special fasteners have been used to replace standard bolted cable heads, transformers, wall bushings, busbars and other equipment, and no overheating failure has occurred. safe question.

Because this patented technology has changed traditional practices for many years, special attention should be paid when installing and using special fasteners for electrical contacts:

1. Electrical contact drilling: Because the bolt heads and nuts of the special fasteners are larger than the original standard parts, the distance between the two holes must be strictly in accordance with the national standard GBJ149-90 page 11-12 table 2.2.2, and the minimum between the two nuts should be ensured. The spacing shall not be less than 3mm. At the electrical contact conductors connected by four special fasteners, in order to avoid drilling errors during processing, the hole spacing should be increased by 1mm.

Special reminder: The effective cross-sectional area calculated by this patented technology and product is different from the traditional customary method. Only the area where the nut is compressed is calculated, and the effective cross-sectional area is directly affected by the hole drilling too large. It is generally believed that the contact surface is not completely equal to the effective cross-sectional area. Only the cross-sectional area under sufficient pressure and constant pressure for a long time can be regarded as the effective current-carrying cross-sectional area. Therefore, if the apertures at both ends of the contact are inconsistent, the small aperture can be enlarged to the same large aperture if possible, and then the electrical contact at this place can be connected with a special fastener with the same large aperture. Do not save trouble, use small-aperture special fasteners to connect the two ends of different sizes, so the electrical contacts connected must be overheated!

2. Removal of the oxide film on the surface of the electrical contact: After drilling, the burr can be polished with a file first. When removing the oxide film on the surface (the silver-plated surface does not need to be polished), it is best to use a copper wire brush. After removing the oxide film, apply it immediately A very thin layer of power compound grease is reserved. (Commonly known as electric compound grease as conductive paste, this will cause people to misunderstand, don't think that the conductivity is good after applying more!)

Third, the special fasteners for electrical contacts must be tightened under any circumstances. The wrenches used for special fasteners are much longer than standard parts, and the tightening force according to the general staff has greatly exceeded the original regulations, and the pressure is sufficient. During construction, especially when the special handle designed and produced by us is used, since the force arm is long when tightening the standard nut, the nut of the special fastener can be tightened according to the torque value provided by us. The anti-loosening nut is a standard nut, tighten it according to the torque value of the standard nut to achieve the purpose of preventing loosening.

Special reminder: The traditional saying that the explanation that standard bolts cannot be tightened too tightly when connecting aluminum busbars does not conform to the actual situation on site! The key to the problem lies in the standard bolts. When using special fasteners for electrical contacts, the pressure is the key to overheating of the contacts, because increasing the contact pressure will reduce the contact resistance.

4. For the copper and aluminum conductors, they can be directly connected with special fasteners! After the surface oxide film is removed, a thin layer of power compound grease is applied, and the surface is basically at the effective current-carrying cross-sectional area where the special fasteners are compressed for a long time Will not oxidize, and the electrical contacts will not corrode if the contact surface is not heated. The original tinning process has a large contact resistance. When using a copper-aluminum transition plate, accidents may occur due to the insufficiency of the copper-aluminum butt welding during processing. Only the electrical contacts where the copper-aluminum joints are completely welded together can be used. (The butt welding process cannot solve this problem!)

To solve the problem of electrical contact overheating, in addition to the theory that conforms to the actual situation and has been tested in practice, there are reasonable and qualified ones, but the hot electrical contacts and special fasteners are also required to be engaged in the installation and production of electrical contacts. , Maintenance personnel work together to ensure the quality of the installation. This and the occurrence of an overheating fault and then a power outage should be regarded as a "one-and-for-all" thing! It is our job to solve the electrical contact overheating fault! The complete elimination of the electrical contact overheating accident is our ultimate Goal! Let us work together to completely solve the "beneficial merit" of the overheating of electrical contacts!

Overheating electrical contacts and fasteners Patent No.: ZL 01214234-4

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