1. During the overload design process, if the conductor and equipment are not selected correctly, or if the current carried exceeds the rated value, the equipment will overheat.
2. Poor heat dissipation. Various electrical equipment usually have heat dissipation or ventilation measures. If these measures are damaged, the device may overheat.
3. Poor contact. Poor connection of wire connectors, poor contact of movable contacts, and electrolytic corrosion of copper and aluminum joints may cause overheating.
4. The insulation damage or long-term overvoltage, eddy current loss and hysteresis loss of the iron core heating transformer and the motor will cause the iron core of the transformer and the motor to heat up, which is easy to overheat.
5. Electrical appliances such as lamps and electric stoves that directly use the heat generated by electric current may cause overheating if installed or used improperly. If the electrical equipment is overheated due to the above or other reasons, the temperature of the conductor will rise, and the surrounding flammable materials or objects will be heated, which may cause a fire.
6. During a short circuit, the current in the line will usually increase several to several tens of times, and a large amount of heat energy will be generated sharply. This heat immediately burns through the insulating layer of the conductor. If the heat is transferred to the surrounding combustibles, it will cause combustion. The reason for the short circuit is that the insulation layer of the equipment is aging or loses its insulation capacity due to high temperature, humidity and corrosion, or the insulation layer is mechanically damaged during the installation of electrical equipment. In addition, lightning insulation breakdown, wiring errors, shell collisions, etc. may cause short-circuit failures.
When the DC resistance tester fails during use, the operator should immediately seek help from personnel and do not dispose of it at will.