Causes of abnormal damage to the pipe and line joints in the single-head heating pipe
When the equipment uses the heating tube for a long time heating, occasionally there will be abnormal overheating damage at the joint of the heating tube and the line due to the long time heating, causing the equipment to be terminated, and the heating tube can only continue to work if the heating tube is replaced. How did the problem form? Because it is an accident, many people disagree, but there are also some people who want to figure out the problem to prevent it before it happens, but don't know how to do it. Yancheng Laiyuan Electric Equipment Co., Ltd. sorted out the electrical connection of electric heating elements such as breakage of lead wires, crimping bolts, and nuts burning and rusting.
Head, abnormal overheating damage, possible reasons:
The main reason for this abnormal overheating damage is due to incorrect electrical installation wiring methods. Unlike conventional electrical equipment component circuit joints (contacts) requirements, electrical joints of electric heating components require not only correct and reliable wiring and low contact resistance, but also certain heat dissipation characteristics and high oxidation and corrosion resistance.
In addition to the more serious corrosive gases and liquids (such as constant temperature water baths, salt baths) in the workplace of electric heating elements, high-temperature oxidation corrosion is the most common direct cause of damage to the joints of electric heating elements.
We can take measures from the following aspects to reduce the working temperature of the electrical joints of the heating tube heating element and improve the working reliability of the electrical heating element joints.
(1) Enhance the contact pressure between the crimped connection conductors: within a certain pressure range, the greater the pressure, the smaller the contact resistance, but if the pressure exceeds a certain limit, the contact resistance will no longer increase with the pressure. Big and obvious changes. The purpose of crimping wire bolts and nuts with metal spring pads of corresponding specifications-is to ensure.
Always maintain a moderate and constant contact pressure between the connecting conductors to reduce the contact between the conductors. Since most of the lead-out connecting wires of the heating element are themselves heating conductors, and the temperature fluctuations in the working place of their joints are large. The thermal expansion and cold contraction between the connection points of the wiring are not equal in size, which creates a gap between the contacts, which causes the contact resistance to increase, and the temperature of the contact rises when the current passes. The installation of spring pads between the contacts can compensate the gap between the connecting conductors during thermal expansion and contraction, maintain the constant contact pressure and the gap between the contact surfaces, thereby ensuring the constant contact resistance between the contacts.
(2) Reduce the resistance value of the wiring of the electric heating element: usually the electric heating element is directly drawn from the internal heating wire (resistance wire) as its connection line (this is the most common in general electric heating furnaces). The heat generated at the electrical joint is partly generated by the contact resistance of the joint itself, and the other part is generated by the resistance of the wiring from the electric heating element. For the latter, reduce the contact heating by reducing the resistance value of the lead-out wiring, and make the lead-out terminal of the electric heating element at the production site (such as the electric furnace wire terminal and the electric iron heating chip terminal, according to the main heating area and the terminal The distance between the two (set it to 1), leave the heating wire longer than 2L or 3L, and straighten it, and then connect 2 or 3 strands in parallel to make it smooth-after the body, according to the actual situation Then the joint is bent or crimped, so that due to the increase in the contact area, the resistance value of the lead part of the heating element will drop to 1/3~1/2 of the original value, and the corresponding heat generation will also drop to 1/ of the original value. 3~1/2. If the diameter of the heating wire is small, the number of strands of the lead wire of the electric heater that are bent back and forth can be increased accordingly.
(3) Enhance the heat dissipation and ventilation effect at the electrical joints of the electric heating elements: For high-power equipment, due to the number of electric heating elements and the corresponding electrical connection points, the contact resistance and lead resistance of the connection points also generate more heat. If the heat is not dissipated in time, local overheating will occur near the electrical contacts and the leads, which will cause overheating and high-temperature corrosion and damage to the leads and contacts of the electric heating element. Therefore, for the wiring of high-power electric heating equipment, the connection between the main power line and each heating element branch line generally does not use direct crimping or splicing, but should be equipped with a middle with a certain thermal conductivity and heat dissipation effect. Transitional connection terminal.