When the equipment uses the heating tube for a long time heating, occasionally, the joint of the heating tube and the wire will be damaged due to abnormal overheating due to the long time heating, causing the equipment to terminate the replacement of the heating tube before it can continue to work. How did the problem form? Because it is an accident, many people disagree, but there are also some people who want to figure out how to prevent problems before they happen, but don't know how to do it. Here, the manager of Yancheng Songtaisun sorted out the electrical connectors of electric heating elements such as broken lead wires, crimped bolts, and nuts burned and rusted. The possible causes of abnormal overheating and damage:
The main reason for this abnormal overheating damage is the incorrect wiring method of the electrical installation. Different from the requirements of conventional electrical equipment and component circuit joints (contacts), the 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 resistance to oxidation and corrosion. . In addition to the more serious corrosive gases and liquids (such as constant temperature water baths, salt baths) in the work place of electric heating elements, high-temperature oxidation corrosion is the most common direct cause of damage to the joints of electric heating elements.
Measures can be taken from the following aspects to reduce the operating temperature at the electrical joint of the heating tube electric heating element and improve the working reliability of the electric heating element joint.
(1) Strengthen the contact pressure between the crimping 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 Significant changes have taken place. One of the purposes of crimping wire bolts and nuts with metal spring pads of corresponding specifications is to ensure that a moderate and constant contact pressure between the connecting conductors is always maintained 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 very 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 for the gap between the connecting conductors during thermal expansion and contraction, maintaining the constant contact pressure and the gap between the contact surfaces, so as to ensure 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). Part of the heat generated at the electrical joint is 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 contact heating by reducing the resistance value of the lead-out wiring. When the lead-out terminal of the electric heating element (such as the electric furnace wire terminal and the electric iron heating chip terminal) is made at the production site, 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, straighten it, and then connect 2 or 3 strands in parallel to make them integrated, 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 electric heating elements: For high-power equipment, due to the large number of electric heating elements and corresponding electrical connection points, the contact resistance and lead resistance of the connection points will also generate more heat. If the heat is not dissipated in time, local overheating will occur near the electrical contacts and around 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 cord 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. This terminal can be a copper bar with a larger surface area, or a stainless steel plate or galvanized (drilled) flat iron. Avoid heat; accumulation; the formation of high temperature zone, thereby overcoming the occurrence of local overheating.
