Under the guidance of the "overheating" theory, the method PCT/CN/2010/079856 to eliminate the overheating of electrical contacts must meet the following "six requirements".

1. The effective current-carrying cross-sectional area of ​​the electrical contact (joint) is more than 1.5 times the cross-sectional area of ​​its conductor (line); (the larger the effective current-carrying cross-sectional area when conditions permit, the better)

The so-called "effective current-carrying cross-sectional area" refers to the part of the "contact surface" that has sufficient pressure after long-term energization to pass the rated current, including short-circuit current.

2. When the detachable electrical contacts are connected by "overheating electrical contact special fasteners", the pressure of the busbar joints can be between 8-10MPa, not less than 8MPa. When conditions permit, try to tighten the points. (According to the general arm strength of the staff, tighten it hard)

Remind again: When the standard bolts were used to connect the busbar in the original GBJ149, the argument that "cannot be tightened too tightly" due to the bolt itself is incorrect. It is also impossible to tighten (loose) the point where the current is large (small), and use alloy aluminum or copper bolts for large currents.

3. The corrosion prevention of electrical contacts (joints) is very important. Low-voltage, low-current detachable electrical contacts can be considered silver-plated, tin, high-voltage, and high-current. The main solution is not to reduce the pressure and the effective current-carrying area due to metallic fatigue. For the split-and-close electrical contact, first consider the reduction of the "effective current-carrying cross-sectional area" caused by arc burn contact surface.

What we mean by anti-corrosion refers to the prevention of oxidation and corrosion of the contact surface before power-on in research, design, manufacturing, installation and power-on. Conductors (wires) that have been energized, especially multi-strand wires and cables, are involved in overhaul and technical transformation. The oxide film on the root surface must be removed, a crimping device clamp should be used, and the contact surface should be cleaned to prevent oxidation.

4. The use of enlarged and thickened "special fasteners for overheating electrical contacts" Chuanke Jianzi [2011] No. 018, National Science and Technology Achievement Network 9512011Y0026 to connect electrical contacts (joints) can effectively prevent copper, Aluminum metallic fatigue.

5. "Special fasteners for overheating electrical contacts" adopt a unique concave design (this is also the key point of protection in the international, invention patents, and methods to eliminate overheating of electrical contacts) when passing short-circuit current, electrical contacts The dynamic stability and thermal stability of the (joint) are quite obvious.

6. The temperature of the electrical contact (joint) should be lower than the temperature of its conductor (line) by more than 5% after half an hour with 1.5-2 times the rated current. When the conditions permit, the longer the time is, the better. After the results and experience are obtained, the actual situation of the site can be used during manufacturing and installation, and a few targeted tests will be sufficient.)

It is necessary to facilitate the disassembly of electrical contacts (joints) during electrical maintenance and pre-testing, and should be suitable for China's national conditions and system status, and the product should be able to be used importantly.

The "Four Basic Principles" for solving and eliminating the overheating of electrical contacts (the first part) and the six technical requirements for "overheating electrical contacts", as well as international and invention patents, can eliminate overheating of electrical contacts (joints). It can eliminate the problems caused by overheating of electrical contacts: electrical equipment burned out, short circuit, power supply interruption, airplane, train crash, electrical fire, automobile "spontaneous combustion" and other accidents, which are harmful to the country, power system, various fields, various industries, including every The safety and economic effects of all electric citizens are very significant.

Sichuan Renyi Electric Co., Ltd.

Senior technician for substation maintenance: Ren Yi