There are two kinds of refrigerators: PTC starter and hammer starter.
PTC is the abbreviation of polymeric positive temperature coefficient, which is a polymer positive temperature coefficient device. It can protect the circuit when the current surge is too large and the temperature is too high. When it is used, it is connected in series in the circuit. Under normal circumstances, its resistance is very small and its loss is very small, which does not affect the normal work of the circuit. However, if overcurrent (such as short circuit) occurs, its temperature will rise, and its resistance will rise sharply, so as to limit the current and avoid damaging the components in the circuit. When the fault is eliminated, the temperature of the PPTC device automatically drops and returns to the low resistance state, so the PPTC device is also called a reversible fuse.
the working principle of p>ptc
the self-recovery fuse is made of polymer material with conductive particles. Its basic principle is a kind of energy balance. When current flows through the element, it generates heat, and part of the generated heat is dissipated to the environment, and part of it increases the temperature of polymer material. Under the working current, the generated heat and the dissipated heat reach a balance, and the current can pass normally. When excessive current passes, A large amount of heat generated by components can't be dissipated in time, which leads to the temperature rise of polymer materials. When the temperature reaches the crystallization melting temperature of materials, polymer materials gather and expand, blocking the conductive path composed of conductive particles, which leads to the rapid rise of resistance and limits the passage of large current, thus playing the role of overcurrent protection.
The function of the heavy hammer starter in the circuit is that when the compressor is connected to the power supply, the starting current will be very large. The electromagnetic force generated by the coil on the starter is also very large. Under the action of this electromagnetic force, the heavy hammer in the starter moves, making the moving contact contact with the fixed contact of the starting winding, connecting the starting winding of the compressor into the circuit, and the compressor starts to operate, as shown in Figure 3. At this time, the starting current gradually decreases. When the compressor revolution reaches 75 ~ 8% of the synchronous revolution, the electromagnetic force on the starter can no longer suck up the heavy hammer. When the heavy hammer descends, the moving contact and the fixed contact are disconnected, and the starting winding is disconnected from the circuit, and the heavy hammer starter completes the starting task. When the power supply voltage is lower than the allowable range, the heavy hammer of the starter can't be sucked up by electromagnetic force, and the starting winding can't be connected to the circuit, so the compressor can't be started. At this time, the current passing through the running winding will burn out the winding. When the power supply voltage is too high and exceeds the allowable range, the moving contact in the heavy hammer starter will be stuck to the fixed contact of the starting winding, and the starting winding can not be disconnected from the circuit and burned out, so that the heavy hammer starter can not successfully complete the starting task of the compressor. To choose a heavy hammer starter to match the compressor, it is actually required that the heavy hammer starter can make the compressor start smoothly when the voltage is low or high.
PTC judgment is very simple, that is, shake it and listen for the sound of debris colliding. If there is, the components are damaged, which makes the compressor unable to start. Heavy hammer damage is rare.
refrigerator is a kind of refrigeration equipment to keep a constant low temperature, and it is also a kind of civil product to keep food or other items at a constant low temperature. There are compressors, ice makers, cabinets or boxes for freezing, and storage boxes with refrigeration devices in the box.
the capacity of household refrigerators is usually 2~5 liters. In 191, the world's first domestic refrigerator with compression refrigeration came out in the United States. In 1925, Lido Company of Sweden developed the household absorption refrigerator. In 1927, the American General Electric Company developed a fully enclosed refrigerator. In 193, air-cooled continuous diffusion absorption refrigerators with different heating methods were put on the market. In 1931, a new refrigerant Freon 12 was successfully developed. Domestic thermoelectric refrigerators began to be produced in the second half of 195s, and China began to produce refrigerators in 195s.
people have known from a very early age that keeping food at a low temperature is not easy to rot. Over 2 BC, the ancient inhabitants of the Euphrates River and Tigris River basins in ancient Babylonia, West Asia, began to build ice cubes in pits to refrigerate meat. In Shang Dynasty (the 11th century before the first day of 17th century BC), China also knew how to use ice cubes to refrigerate and preserve food. In the Middle Ages, there were primitive refrigerators that put ice cubes in special water cabinets or stone cabinets to preserve food in many countries. Until the 185s, this kind of refrigerator was still on sale in America.
in p>1822, Faraday, a famous British physicist, discovered that gases such as carbon oxide, ammonia, chlorine and so on would become liquids under pressure, and then become gases when the pressure was reduced. In the process of changing from liquid to gas, it will absorb a lot of heat, which will make the surrounding temperature drop rapidly. Faraday's discovery provided a theoretical basis for later generations to invent artificial refrigeration technologies such as compressors. The first artificial refrigeration compressor was invented by Harrison in 1851. Harrison, the owner of the Australian newspaper Quilen Advertising, once cleaned the type with ether, and found that the ether coating on the metal had a strong cooling effect. Ether is a liquid with a very low boiling point, and it is easy to absorb heat by evaporation. Harrison developed a refrigerator using ether and refrigerator pressure pump through research, and applied it to a brewery in Victoria, Australia, for refrigeration and cooling during brewing.
in p>1873, Karl von Linde, a German chemist and engineer, invented a refrigerator with ammonia as the refrigerant. Linde used a small steam engine to drive the compression system, so that ammonia was repeatedly compressed and evaporated, resulting in refrigeration. Linde first applied his invention to Sai Doummar Brewery in Wiesbaden, and designed and manufactured an industrial refrigerator. Later, he improved the industrial refrigerator. Miniaturizing it, in 1879, the world's first home refrigerator with artificial refrigeration was manufactured. This steam-powered refrigerator was quickly put into production, and by 1891, 12, units had been sold in Germany and the United States.
The first refrigerator with a compressor driven by a motor was invented by Swedish engineers Brighton and Mendes in 1923. Later, an American company bought their patent and produced the first batch of household refrigerators in 1925. In the first refrigerator, the electric compressor and the refrigerator were separated, and the latter was usually placed in the cellar or storage room of the family and connected with the electric compressor through pipes, and then they were combined into one. Before 193s, most refrigerants used in refrigerators were unsafe, such as ether, ammonia, sulfuric acid, etc., which were flammable, corrosive or irritating. Later, I began to search for safer refrigerants and found freon. Freon is a non-toxic, non-corrosive, non-flammable fluorine compound, which soon became the refrigerant of various refrigeration equipment and has been used for more than 5 years. However, it has been found that freon has a destructive effect on the ozone layer of the earth's atmosphere. So people began to look for new and better refrigerants.