Microwave Oven

[wēi bō lú]

Cooking tools for heating food with microwave

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Microwave oven (microwave oven/microwave), as its name implies, is a kind of microwave heating Modern cooking stoves for food.

Microwave is a kind of electromagnetic wave 。 The microwave oven is powered by, Magnetron , control circuit, cooking cavity and other parts. The power supply provides about 4000 V high voltage to the magnetron. Under the excitation of the power supply, the magnetron continuously generates microwave, and then Waveguide System, coupled to the cooking cavity. There is a rotatable Agitator Because the stirrer is a fan shaped metal that reflects microwave in all directions after rising, it can evenly distribute microwave energy in the cooking cavity to heat food. The power range of microwave oven is generally 500~1000 watts.

Chinese name: Microwave Oven
Foreign name: microwave oven/microwave

Category: cooking utensils
Principle: electromagnetic wave heating

catalog

eight Development trend
▪ Intelligent optimization
▪ Multifunction
▪ Energy saving and environmental protection
▪ healthy
▪ Easy to operate
nine Basic structure
ten Choose correctly

national standard

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Microwave oven industry Energy efficiency grade national standard GB24849-2010 Minimum Energy Efficiency Values and Energy Efficiency Grades for Household and Similar Microwave Ovens was officially released and officially implemented on December 1, 2010.

Microwave Oven Energy efficiency standards Implementation will promote the industry Product upgrade Technological upgrading is conducive to the overall value of the industry and further improving the international market competitive power; For the society, it is not only conducive to consumer saving Usage cost , also beneficial to conserve energy ,reduce emissions Therefore, the whole industry is taking effective measures to respond positively.

development history

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stay the Second World War During the period (1945) Radar Engineer Spencer accidentally found the chocolate bar in his pocket melted and sticky when he was doing radar experiments. He suspected that it was caused by his own temperature. Later, he found the microwave in many consecutive experiments heat effect 。^[1] Using this thermal effect, the United States issued the first patent for the use of microwave in 1945. In 1947, Raytheon Corporation of the United States developed the first microwave oven radar oven in the world. In the 1940s, microwave ovens were mostly used for industry and commerce. After continuous improvement, the household microwave oven was introduced in 1955 Western Europe It was born in the 1960s and began to enter the family. In the 1970s, the cost of microwave ovens continued to decline due to the solution of radiation safety, ease of operation, that is, multi-function and other issues. It was further promoted and used, and formed an important family industry. At the same time, the variety and technology of microwave ovens continued to improve. In the 1980s and 1990s, control technology 、 Sensing technology The continuous application of microwave ovens has made them widely popular.

working principle

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Microwave oven is a cooking appliance that uses food to absorb microwave energy in microwave field to heat itself. In the microwave oven Microwave generator The generated microwave establishes a microwave electric field in the microwave oven cavity, and certain measures are taken to make this microwave electric field in the oven cavity as much as possible uniform distribution , put food into the microwave electric field control center Control its cooking time and microwave electric field intensity To carry out various cooking processes.

Generally speaking, microwave is of high frequency electromagnetic wave It does not generate heat itself. There are microwaves everywhere in the universe and nature, but there are natural microwaves. Because they are scattered and not concentrated, food cannot be heated. The microwave oven uses its internal Magnetron , convert electric energy into microwave, penetrate food with 2450MHz oscillation frequency, when microwave is absorbed by food Polar molecule (such as water, fat protein , sugar, etc.) is attracted to oscillate rapidly at a rate of 2.45 billion times per second, and the macro performance of this oscillation is that the food is heated.

microwave heating The principle of microwave radiation When it comes to food, food always contains a certain amount of water, and water is composed of polar molecules (the positive and negative charge centers of molecules are not coincident even when the external electric field does not exist). The orientation of such polar molecules will change with the microwave field. Because of this movement of water polar molecules in food. As well as the interaction between adjacent molecules, a phenomenon similar to friction occurs, which makes the water temperature rise. Therefore, the temperature of food also rises. The food heated by microwave is heated inside at the same time, so that the whole object is heated evenly, heating rate Also fast. It heats the food 5 cm deep at a frequency of 2.45 billion times per second, accelerating the molecular movement.

Microwave characteristics

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Microwave refers to the electromagnetic wave whose frequency ranges from 300MHz to 3000GHz, and its corresponding wavelength ranges from 1m to 0.1mm. This paragraph Electromagnetic spectrum include Decimeter wave (frequency from 300MHz to 3GHz) Centimeter wave (frequency from 3GHz to 30GHz) Millimeter wave (frequency from 30GHz to 300GHz) and Submillimeter wave (The frequency ranges from 300GHz to 3000GHz).

from Electron optics From the point of view of physics, microwave Electromagnetic spectrum It has the following important characteristics different from other bands:

1. Photolikeness and sonolikeness

The wavelength of microwave is shorter than that of ordinary objects on the earth, such as aircraft, ships, cars Tank , rockets, missiles, buildings, etc. are much smaller or of the same magnitude. This makes the characteristics of microwave geometrical optics Similarity Opticity 。 Therefore, using microwave to work can reduce the circuit size and make the system more compact. It can be designed to be small in size, narrow in beam directional Very strong and high gain antenna system , receive from ground or Cosmic space Reflected by various objects weak signal So as to determine the orientation and distance of the object and analyze the target characteristics. Because the wavelength of microwave is of the same magnitude as the size of objects such as radio equipment in the laboratory, the characteristics of microwave are similar to those of sound waves, which is called acoustical similarity. for example Microwave waveguide Similar to Microphone Horn antenna and Slot antenna Similar to acoustic horn, whistle and flute Microwave resonator Similar to acoustics Resonance box Etc.

2. Penetrability

When microwave irradiates on the dielectric body, it can penetrate into the interior of the material the ionosphere , become a human probe outer space The "cosmic window" microwave can penetrate through clouds, rain, vegetation, snow and surface layer, and has the ability to work all day and all day remote sensing technique The important wave band of microwave can penetrate organisms and become medicine Diathermy The millimeter wave can also penetrate Plasma , Yes long-range missile and spacecraft return atmosphere Communication and terminal guidance Important means.

3. Nonionization

The quantum energy of microwave is not large enough to change the internal structure of material molecules or destroy the bonds between molecules. As known from physics, molecules, atoms and Nucleus Plus electromagnetic field Under the action of the periodic force of resonance All phenomena occur in the microwave range, so microwave provides an effective research means to explore the internal structure and basic characteristics of materials. On the other hand, many devices for microwave band can be developed by using this characteristic and principle.

4. Informational

Because of the high frequency of microwave Relative bandwidth Next, its available frequency band Very wide, up to hundreds or even thousands Megahertz 。 This is low frequency radio waves Incomparable. This means that the microwave Information capacity Very big. So modern multiplex communication system , including satellite communication system Almost without exception, they work in the microwave band. In addition, microwave signal can also provide phase information, polarization information, Doppler frequency information, which is very important in target detection, remote sensing, target feature analysis and other applications.

Two effects

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1. Wave heat effect. The electromagnetic field in the microwave oven cavity changes at a rate of 2.45 billion times per second (the microwave frequency is 2450MHz), which acts on the water Molecules and other polar molecules swing back and forth 2.45 billion times/second due to the high-speed wheel swing friction movement between water molecules High fever To achieve the purpose of heating.

2、 biological effect 。 Because of microorganisms Cytosol The ability to absorb microwave is better than that of other surrounding media, so the cells in the microwave electromagnetic field will break quickly and cause bacteria cell death 。

Three characteristics

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1. Reflectivity. The microwave will be reflected back when it touches the metal, so the inner wall is made of specially treated steel plate. According to the reflection effect caused by the inner wall of the microwave oven, the microwave can penetrate the food back and forth to enhance the thermal efficiency. However, metal containers shall not be used in the furnace, otherwise the heating time will be affected and even the furnace will be ignited.

2. Penetrability. Microwave to general Ceramic ware Glass, heat-resistant plastic, wood, bamboo, etc. have a penetrating effect, so they are the best utensils for microwave cooking.

3、 Absorptivity 。 All kinds of food can absorb microwave, causing the molecules in food to generate heat energy through vibration and friction. However, its penetration into various foods depends on its Quality and quantity The size, thickness and other factors.

Risk disputes

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The Viewpoint of "Microwave Carcinogenesis"

Because microwave is a kind of radiation, there is a wrong view that it can cause cancer. In fact, microwave is a kind of electromagnetic wave With radio waves and telegrams infrared , and visible light It's essentially the same thing. They differ only in frequency. Microwave frequency is higher than radio wave, lower than infrared and visible light. Electromagnetic waves at this frequency band will not cause cancer.

Although it is also called "radiation", microwave and X-ray The radiation produced by radioisotopes is different. The latter two are more dangerous ionizing radiation , while microwave belongs to Nonionizing radiation The risks of the two are not the same. Although X-ray is also an electromagnetic wave Frequency ratio The microwave is too high, so the energy is also high; and radio isotope In the process of decay, particles will be emitted, so they can make organisms produce canceration 。

Damage to human body caused by microwave heating effect

The risk of microwave oven lies in its heating capacity, which will also cause harm to human body. The microwave oven with qualified quality can reduce the leaked microwave energy through the internal shielding device.

scientific research The minimum microwave power causing harm to human body was found, and the standard of microwave oven leakage power was formulated. For example, in the United States, the power per square centimeter should not exceed 5 milliwatts at a distance of about 5 centimeters from the microwave oven; China's standard is more stringent, 1 milliwatt. And the microwave energy is weakened according to the square of the distance. If we take 1 milliwatt at 5 cm, it will be reduced to 1% milliwatt at 50 cm. Therefore, as long as it is a qualified microwave oven product that is not damaged in use, it will not leak microwave that can harm human body.

"Microwave oven makes food Carcinogen ”'s point of view

No matter what heating method, if the food is heated too high, carcinogens may be produced. For example, over 120 degrees, amino acid and carbohydrate Reaction may occur Acrylamide Like suspected carcinogens, such as frying and baking various pasta and biscuits a snack 、 French fries 、 Potato chips 、 coffee bean And other foods will be produced; If the temperature exceeds 200 ℃, the protein may produce heterocyclic amine carcinogens, such as fish When frying and cooking; More than 300 degrees, fat in food will be produced in large quantities Benzopyrene Carcinogen like substances, such as shish kebab 、 barbecue When the meat is burnt due to improper cooking.

If the microwave oven is used for heating, it generally does not need to reach more than 100 degrees; For porridge, soup, milk, rice noodle For such high moisture food, as long as the water is not evaporated dry, the food temperature will always be maintained at 100 degrees, and carcinogens will not occur. Therefore, normal microwave oven will not produce food Carcinogen 。 Even according to Related research Compared with traditional heating methods, especially roasting, roasting and frying, microwave oven can also effectively reduce the production of carcinogens mentioned above.

"Microwave order Plastic container release Hazardous substances ”'s point of view

Some plastics may release some harmful ingredients when heated. American Food Drug management Bureau（ FDA ）The possible harmful effects of various plastic containers on food during normal microwave heating were determined Amount of substance , this amount is required to be less than Animal experiment Only one percent or even one thousandth of the determined harmful dose can be marked as "microwave heating". Therefore, it is quite safe for those qualified plastic containers marked as "microwave heating". If you are not sure, you can also use ceramics or Glass container 。

In June 2023, a study by scientists at the University of Nebraska Lincoln in the United States found that when heated in a microwave oven, a large number of micro plastic particles would be released from the plastic containers that package baby food. Relevant research was published in the journal Environmental Science and Technology. At present, the release of microplastics from plastic containers under heating has caused heated debate. However, whether microwave heating has increased the release risk of microplastics is still controversial. In view of the unreasonable temperature control of microwave ovens and the lack of comparison with traditional heating methods in the above research, a new research team from the School of Food, Jiangnan University, also published in Environmental Science and Technology in May 2024, found that compared with water bath heating at the same heating rate, The micro plastic particles released from the plastic container of baby food heated by microwave oven will not be too high, and the quantity of micro plastic particles released from the two heating methods is in the same order of magnitude. Therefore, compared with water bath heating, the conclusion that microwave heating plastic containers has special risks is not tenable.^[3-4]

Safety accident of microwave oven

According to the investigation of the US Food and Drug Administration (FDA), the safety accidents of microwave ovens are often caused by improper use. The following two types of accidents are most common:

1. Liquid overheating. During microwave heating, because the water does not flow, but the temperature rises, it may still "not open" beyond the boiling point, resulting in overheating. At this time, the water will boil violently if there is a little disturbance, which is easy to happen Scald accident. The cleaner the container and the cleaner the water, the more prone to such accidents.

2. Eggs explode. The microwave oven cannot heat the eggs, because overheating inside the eggs will generate greater pressure, which may explode if the pressure is released due to external interference.

Influence of microwave oven radiation on human and animals

The radiation in the microwave oven is very large, which can make the objects with water and oil inside produce heat to cook food, but the manufacturer of the microwave oven has already done a good job Safety measures , outside the microwave oven Radiation Just one 40W Fluorescent lamp It has almost no effect on human body. Chinese Preventive Medicine Association Experts, University of Wisconsin Professor Adel, a physics professor, has studied the effects of microwave radiation on small animals and humans for more than 25 years. She has conducted experiments on animals and humans in the microwave room. As a result, animals appear very excited in the microwave room, while humans feel the same as enjoying the bright sunshine. She explained that although microwave and X-ray Gamma ray Equivalency genus Radiation However, its quantum energy is millions of times different. She pointed out that the only way for microwaves to kill cells is to let them themselves“ heat death ”However, the radiation leaked from the microwave oven cannot reach this level. In this way, microwave oven will not be harmful human health 。

Microwave food advantages and disadvantages

An article titled "Microwave food has more disadvantages than advantages and is extremely harmful to health" was reported in a well-known domestic newspaper, which proposed that microwave heated food would be harmful to health and even carcinogenic. Many readers read it and discussed how harmful microwave food is to the body. Many Chinese experts also expressed their opinions on this statement.

Microwave food refers to the food heated and cooked in the microwave oven. Since the advent of microwave oven in the 1940s, microwave oven has penetrated into people's daily life. Using microwave oven to heat food has many advantages, such as cleanness, rapidity, convenience, etc. Therefore, more and more people have shown an acceptable attitude towards microwave food and the use of microwave oven. Data shows that 90% of households in the United States use microwave ovens. Even in China, where the economy is relatively backward Market demand It is also increasing rapidly year by year.

In today's increasingly fast pace of life, fast and convenient microwave food has become the "sweet cake" in the eyes of many people. However, for a long time, an article about the harm of microwave heating food to human health made microwave food become a "far away" in the eyes of many people. Is microwave food as harmful as the article says?

The microwave oven has been used for many years, but there is no evidence that some people are harming their health because of the food heated by microwave. Even, there are only some claims about the damage of microwave leakage to human body, and there is no proof of facts.

Development trend

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With the progress of science and technology, electronic technology sensor technology And material technology has been greatly developed in recent years. In order to meet the use requirements of microwave oven consumers, domestic and foreign microwave oven research and development institutions and production plants have applied various advanced modern technologies to microwave ovens and launched a series of new and advanced microwave oven products. These new microwave oven products reflect the Development trend , mainly in the following aspects:

Intelligent optimization

use microcomputer control technology And sensor sensing technology to realize intelligent heating and cooking of microwave oven technological development A major direction of. This intelligent microwave oven does not require the user to input the cooking time, heating power, food weight and other parameters on the operating button. Just press the start button, the sensor in the microwave oven will detect the food temperature Steam humidity And other parameters are continuously output to the microcomputer control chip, which outputs corresponding instructions after a series of calculations, comparisons and analyses, Auto-Control The heating time and power of the microwave oven are intelligent fully automatic Cooking. along with fuzzy control The research, promotion and application of technology and the continuous introduction of various professional fuzzy control chips have greatly improved the intelligent automatic control technology of microwave ovens.

also bar code Technical microwave oven. This microwave oven has a special bar code Code reader And barcode Microwave recipe 。 The user selects an appropriate barcode recipe according to the cooking needs, and after reading it with a code reader, the recipe will be recorded in the microwave oven storage When the user puts in the corresponding dishes and starts the microwave oven, the microwave oven will cook delicious food according to the barcode recipe cooking procedure.

SHARP The produced microwave oven is a high-end microwave oven that combines temperature, humidity, weight and other sensors with a microcomputer processor. Users do not need to set cooking time, heating power or food weight, but just press the start button Sensor Network According to the type and nature of the heated food Auto Select The best heating time, power and temperature can realize high-quality automatic cooking. Germany launched a computer Scanner The multifunctional microwave oven I of is equipped with a sensor, which can measure the weight, height, shape and temperature of food. The computer uses these measurement information to automatically select one of the four working modes for work, including thawing, reheating, barbecue Hot air convection 。 The computer can also scan and identify the type of food, and automatically determine the processing method And cooking time. The microwave oven has different fuzzy control working procedures, which can be used together with dynamic dishes and mixers to cook various foods.

Multifunction

With the acceleration of modern people's life rhythm and Quality of life With the improvement of, higher requirements have been put forward for the cooking of food, so a multi-function microwave oven has emerged. For example Electric oven The barbecue functional component of Microwave barbecue Combined microwave oven Is an example of a multi-function microwave oven. This kind of microwave oven has been very common in China. Its advantage is that it uses microwave energy to quickly cook food to make it fully ripe, and then barbecue and heat it to make the food yellow and crisp, so that the food has a better taste and Visual effect 。 In order to make the cake made by microwave oven soft inside and yellow outside, some microwave oven manufacturers in Japan have introduced a hot air Convection heating Functional microwave oven, this microwave oven will Heating element The generated heat passes through the specially designed convection duct Blower Blow into the microwave oven and bake the cake with high temperature hot air

Energy saving and environmental protection

Energy conservation and environmental protection are two major issues facing mankind at present and in the future. The design and manufacture of microwave oven products also increasingly reflect this trend.

healthy

With people's health environmental awareness With the increase of, more attention has been paid to the restriction of calories in food. As a modern food cooking appliance, microwave oven can cook low calorie health food, which is naturally one of the development trends that should be paid attention to in microwave oven design.

Easy to operate

Generally speaking, with the enhancement of the functions of household appliances, their operation methods often become more complex, which brings inconvenience to people's use. Therefore, while improving the heating and cooking function of the microwave oven, simple operation is an important aspect that deserves attention.

Basic structure

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The microwave oven consists of seven parts:

Magnetron: It is the "heart" of the microwave oven, which generates and emits microwave (DC electric energy is converted into microwave oscillation output). It is actually a Vacuum tube (metal tube).

Power transformer : It is a component that supplies voltage to magnetron.

Furnace chamber: Also called resonant cavity It is the place where food is cooked magnetic material Is made of metal plate. Ventilation holes are provided on the left side and top of the furnace chamber. through Waveguide The microwave in the input oven cavity reflects back and forth in the cavity wall, and each transmission passes through and through the food. When designing the microwave oven, the side length of the oven cavity is usually 1/2 microwave guided waves Multiple of the wavelength, so that when the food is heated, the cavity can maintain resonance The resonance range is widened appropriately.

Waveguide: The microwave power generated by the magnetron is transmitted to the oven cavity to heat food.

Rotary table ： The rotary table is installed at the bottom of the furnace chamber, with a certain height from the furnace bottom Small motor Drive.

fire door : The furnace door is used to take and place food and observe the cooking situation. The furnace door also forms the furnace cavity Anterior wall It is a barrier for the whole microwave oven to prevent microwave leakage.

Time power controller: Choose different power to cook or defrost different foods.

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Function classification

From the aspect of control, it can be divided into two categories: computer microwave oven and mechanical microwave oven.

The computer microwave oven is suitable for young people and people with higher education. The advantage lies in the precise control heating time According to the difference of heating food, there are many procedures to choose from. High grade products may also have some other Additional Features The disadvantage is that there are many keys and the operation is complex and difficult to master.

Mechanical microwave oven is most suitable for middle-aged and elderly people. The advantage is that it is easy to operate and clear, Product reliability Good, suitable for the elderly.

In terms of function Zonation Barbecue type and non barbecue type. People who like to eat barbecue may as well buy barbecue microwave ovens.

Frequency conversion microwave oven Easier than traditional microwave oven Uneven heating Different, the frequency conversion microwave oven uses the microwave energy that is automatically adjusted and continuously output to meet the requirements of different foods for different fires, and truly realizes the automatic control from strong fire to weak fire. It not only guarantees the taste and color of food, but also fully retains the nutrition of food. In addition, the surface or edge of food will not be burned when cooking with low power for a long time. In terms of cooking speed, frequency converter is used instead of frequency converter High voltage transformer And high voltage capacitance, etc Power conversion Partial loss, thermal efficiency Increase by more than 5% Effective power Increase by nearly 10%. Under the same conditions, the cooking time is reduced by 10%. In terms of energy conservation, the energy efficiency is up to about 64%, 62% higher than the national standard level I energy consumption standard.

SHOP A BOOK

With people living standard The continuous improvement of housing conditions Kitchen appliances It has been widely used and developed. As a major category of kitchen appliances, microwave ovens have a wide variety of features, different functions and convenient use, which has brought great convenience to our life. Common varieties can be divided into microwave ovens, barbecue type microwave ovens and frequency conversion microwave ovens. Here's how to buy a microwave oven:

1、 Basic requirements for purchasing microwave ovens

1. Microwave oven is listed in the first batch of national mandatory Safety certification （ CCC Certification), consumers must choose to paste "CCC" on the products in the catalog Certification mark And marked with the corresponding factory code and Certificate Number of products. In order to verify the authenticity of the certification mark and certificate, you can log on to China Certification and Accreditation Administration Official website Query the authentication certificate online.

2. Check the product's an instruction manual , Certificate of Conformity warranty card And whether the accessories are complete.

3. Carefully check the product logo and instructions. country Mandatory standards GB4706.21-2002 Safety of Household and Similar Electrical Appliances - Special Requirements for Microwave Ovens stipulates that the identification of microwave oven products should be clear and standard, and the content should include: trademark, model, specification (such as capacity) Rated voltage Rated Input power Symbol and production of power source nature Enterprise name 、 Rated output power Etc; The instructions shall include warnings to prevent misuse and detailed cleaning methods; On product Operation switch The identification shall be clear and fixed reliably.

4. Check the appearance. The appearance shall be flat and smooth, with uniform color and no obvious color difference. In addition, microwave ovens will produce microwave, so special attention should be paid to the sealing condition of their doors when purchasing Interlock device Whether it is normal.

5. Add water for trial firing. Can be used flower receptacle Add appropriate amount of water to power on for trial burning. After the microwave oven is powered on, the water in the oven will become hot. The shorter the heating time is, the higher the water temperature is, which means the better the heating performance of the microwave oven is. At the same time, after the microwave oven works for a period of time, touch whether the appliance shell is hot. If the appliance shell is hot, it indicates that the heat dissipation condition of the appliance is not good.

6. Choose large scale product quality and Service quality Better knowledge Famous enterprises Industry. Due to the strict quality control of raw materials, parts and products by large-scale manufacturing enterprises, Production equipment Advanced, business management High level, product quality and after-sales service are also more guaranteed.

2、 Special requirements for purchasing microwave ovens

As a kitchen tool for heating and thawing, microwave oven is fast, efficient, easy to use, safe and reliable. It is one of the widely used household appliances and deeply loved by consumers. Consumers should purchase microwave ovens according to their own needs: Hot Dishes Hot rice and unfrozen food, single choice microwave heating Functional microwave oven; If you usually use the microwave oven to cook dishes, you can choose the microwave oven with barbecue. In addition, some microwave ovens on the market have electronic control device , just press control panel Button on the, you can cook the corresponding dishes; Some microwave ovens have the frequency conversion function output power Large, improving the heating performance of the appliance. In a word, consumers should choose suitable microwave ovens according to their own needs and the cost performance of the products, and should buy them in formal sales places to protect their own interests.

(1) The brand should choose the microwave oven that has been approved by the national safety certification.

(2) Type Capacity: There are many kinds of microwave ovens with output power of 500W, 600W, 800W, 1000W, etc. The capacity also has different specifications such as 0.6.0.7.0.9.1.0ft3 (1ft=0.3048m). When choosing, consider not only the family's economic capacity and population, but also Home circuit And the load capacity of the meter. As far as the living standard of 3-4 people in ordinary families is concerned at this stage, it is appropriate to choose an ordinary rotary microwave oven with a power of about 800-1000W, regardless of price, capacity, power supply and other aspects.

(3) Appearance quality: The selection of appearance quality of microwave oven shall include modeling, color surface quality And components.

(a) The modeling is to see whether the product is beautiful and generous.

(b) Color refers to whether the color of the product is your favorite, whether the various colors on the product are coordinated, and whether the color of the product is coordinated with other furniture and appliances in the placement.

(c) The surface quality is to check whether the coating, paint layer or plating on the product surface is mechanical Bruise and Abrasions Whether there are cracks and damages in each component, and whether the processing peaks have been removed.

(d) The panel shall be flat without concavity, scratch, bruise, inorganic processing trace, uniform color, good gloss, and clear patterns and characters.

(4) Power on test: Put the microwave oven turn on electricity , add water, start the microwave oven, and observe the following points:

(a) Observe whether there is lighting in the furnace.

Composition of microwave oven

(b) Observe whether the glass plate in the furnace rotates, and failure to rotate will damage the parts.

(c) Whether the water is heated or not, it is normal to put a cup of 200 ml cold water into a 500 watt microwave oven and boil it for 4 minutes, or into a 600 watt microwave oven and boil it for 3 minutes. If not heat proof Magnetron inoperation.

(d) Yes No Hot air Discharge, if the magnetron works normally Exhaust system Failure to work will damage the microwave oven.

(e) Check according to the instructions Control panel Whether all buttons and knobs are functional.

(f) In the middle of the microwave oven work, if the oven door is opened, the microwave oven should stop working, otherwise a large number of microwave shoots outside the oven will cause harm to people.

(g) A slight "click" sound should be heard when opening the furnace door gently. This proves that the door latch is in good contact with the microswitch.

(h) The noise should not be too loud. One is available Medium wave radio Adjust it to the place where there is no platform and place it near the furnace body. If there is no discharge like noise, it means that the microwave shielding is good and the microwave leakage power is small.

When purchasing microwave ovens, in addition to considering different brands, prices, function types, and appearance differences, it is likely to ignore some other important factors. It is precisely these elements that will directly affect whether you can buy a microwave oven with high cost performance. It is every consumer's pursuit to buy satisfactory products at the most affordable price. Here are some key elements that can't be ignored when you buy a microwave oven, so that you will never "look" again.

Purchasing index

Steaming function

Its steam function product has been on the market since 2004 Steamed vegetable The effect reached the traditional level of steaming vegetables; Moreover, it can be controlled intelligently, which saves worry and time.

Flat

The flat microwave oven not only heats more evenly, but also has more space and can put more food without a turntable.

Nano silver

Whether microwave oven adopts Nano silver liner It is easier to clean, and it can also automatically resist bacteria, saving labor and time.

noise

If the noise is too loud, it will have a certain impact on the life and mood of consumers. You can use a medium wave radio to adjust it to a place where there is no station and place it near the furnace body. If you can't hear the discharge like noise, it means that the microwave shielding is good and the microwave leakage power is small.

Environmental certification

Environmental protection is not only the trend of the world, but also the responsibility of enterprises social responsibility 。

Box size ≠ bottom plate size

Consumers tend to value the brand and capacity when purchasing microwave ovens. They tend to think that the larger the volume, the faster the heating. They ignore the chassis Inner bottom plate The area size of. industry insiders Remind consumers that when choosing a microwave oven, they must pay attention to the size of the floor area of the microwave oven, because the larger the floor area, the faster the heating, the higher the heat, and the more uniform the heating area. Under the premise of the same floor area, the thermal efficiency of the microwave oven with a volume of 23 liters is obviously higher than that of the microwave oven with a volume of 21 liters. Therefore, when purchasing a microwave oven, consumers must "see the essence through the phenomenon" and cannot ignore the size of the bottom plate.

The small platform at the bottom has to be seen

A small platform will protrude at the bottom of the flat microwave oven, and there is a microwave in this small platform Agitator 。 This device disperses the microwave, so that the microwave can be evenly transported upward from the bottom, and then the food in the box can be heated. The larger the area of the small platform, the closer to the area of the bottom plate in the box, the more flexible the microwave mixer will be, and the microwave will be beaten more evenly. If the area of the small platform at the bottom of the microwave oven is very small, the heating effect will be greatly reduced.

The power concept should be distinguished

When consumers purchase microwave ovens, Regular meetings The parameter considered is the power of the microwave oven. When choosing a microwave oven, we should not only look at the power, but also the output power, because the output power is the useful work for heating food. The input power of the microwave oven is usually labeled on the back of the machine. The smaller the difference between input power and output power, the better. The smaller the difference, the greater the effective power of the microwave oven.

Noise is related to power consumption

The microwave oven will generate noise when it is started instantly. You can listen to the noise level of the microwave oven a few seconds later. If the noise at startup is not very different from that after the microwave oven has been running for a few seconds. It proves that the performance of the microwave oven is not very ideal, and it costs Idle work Too much will consume more power.

In addition, like Digital camera Like mobile phones, digital control There is also a "memory" problem with our microwave ovens. For example, when heating milk, there will be a limit of kilograms. Different microwave ovens have different limits. When heating the same kind of food with the same weight, see which machine has the shortest setting time. The less time it takes to ensure that the food is cooked, which proves that the microwave oven Heating speed The faster. Ordinary microwave ovens With heat Milk Roast chicken wings 、 Steamed Rice The customer can ask the salesperson to demonstrate the commonly used functions such as microwave ovens when purchasing them, so as to better choose Energy efficiency ratio Higher microwave ovens.

Safe use

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Taboos

Taboos of microwave oven

1、 contraindicated ordinary Plastic container : First, hot food will deform the plastic container; second, ordinary plastic will be released Toxic Substances , contaminate food, harm human health 。

2. Do not use metal utensils: because the iron, aluminum stainless steel 、 enamel The microwave oven will produce electric spark And reflect the microwave, which not only damages the oven body but also cannot heat food.

3. Do not use closed containers: wide mouth containers should be used when heating liquids, because the heat generated by food heating in closed containers is not easy to dissipate, making containers Internal pressure It is too high to cause blasting accidents.

4: Avoid bottled food with narrow bottleneck: even if the cap is opened, it will expand due to pressure, causing explosion.

5. Do not use half full open bottle Baby food Or put the original bottle into the furnace for heating to prevent the bottle from cracking.

6. All heat-resistant containers such as bamboo ware and lacquer ware and glass products with concave and convex shapes should not be used in microwave ovens.

7. Porcelain dishes cannot be inlaid with gold or silver lace. Use special microwave utensils to put food into the microwave oven for heating.

8. Avoid overtime heating: put food into microwave oven for thawing or heating. If you forget to take it out, if it takes more than 2 hours, you should discard it to avoid causing food poisoning 。 The heating time of the microwave oven depends on the materials and dosage, and is also related to the freshness and water content of the food. Because the heating time of various foods is different, when the heating time required for food is uncertain, a shorter time should be used. After heating, additional heating time can be added according to the raw and cooked degree of food. Otherwise, if the time is too long, the food will become hard, lose its fragrance, color, taste, and even produce toxins. Adjust the timing and power (temperature) knob according to the type of food and cooking requirements. You can read the instructions carefully to understand.

9. Do not heat the meat to half cooked and then use the microwave oven to heat it: because bacteria will still grow in the half cooked food, it is impossible to kill all bacteria when using the microwave oven to heat it for the second time because of the short time. Frozen meat must be thawed in the microwave oven before being heated to cooked food.

10. Do not refreeze the meat thawed in the microwave oven: after the meat is thawed in the microwave oven, the outer layer of low temperature has actually been heated. At this temperature, bacteria can reproduce. Although refreezing can stop its reproduction, it cannot kill live bacteria. If the meat that has been thawed in the microwave oven is put into the refrigerator for freezing, it must be heated to fully cooked.

11. Taboo fried food : Because High temperature oil Splash may occur and cause fire. In case of fire in the furnace due to carelessness, do not open the door, but turn off the power first, and then open the door to cool down after the fire is extinguished.^[2]

12. Do not place the micro oven in the bedroom, and do not cover the radiator grille on the microwave oven with objects.

13. Do not work in front of the microwave oven for a long time: after starting the micro oven, people should stay away from the microwave oven or at least 1 meter away from the microwave oven.

14. It is forbidden to share the same socket with other appliances, and the socket with a single power supply and a grounding wire shall be used.

15. Do not use the microwave oven to warm the baby's milk, because when the milk is heated unevenly, it is easy to burn the baby. In addition, it will destroy the nutrition of milk.

16. Do not use microwave oven to dry clothes or harden Nail Polish Cook soft to prevent fire.

17. Do not remove food from the microwave oven with bare hands. Container After heating, the lid often accumulates steam, which will absorb the heat of food and become very hot. Heat proof gloves or mats should be used to prevent burns.

18. It is not allowed to place food without water in the microwave oven to make it work, which will cause damage to the microwave oven.

Heating matters

Too long heating affects the quality

If the microwave oven is used to heat milk for too long protein Under the action of high temperature, the sol state changes into the gel state, resulting in the appearance of sediment, which affects the quality of dairy products. The longer the milk is heated and the higher the temperature is, the more serious the nutrition loss will be vitamin C The loss is the most serious, followed by lactose 。

Avoid heating to preserve nutrients

Professionals also made it clear that directly putting bagged milk into the microwave oven for heating would have adverse effects on human health. If the packaging materials are not marked with the words "can be heated in microwave oven", it is not suitable to directly put them into the microwave oven for heating.

Cleaning and maintenance

1. After each use, wipe the inner wall of the furnace and the rotary table with a wet towel, wipe off all the moisture with a dry towel, and open the furnace door for a moment to ventilate and dissipate heat. Wipe the door seam and door hinge clean, and do not leave new things that may cause the furnace door to fail to open and close Leakage radiation 。 LG Microwave oven MH6343SDR tank surface adopts high coagulation Dusting &High temperature resistant coating material. Strong microwave reflection ability, stable at high temperature and difficult to penetrate; Improve energy efficiency Utilization It is easier to clean the surface. Test results show that this easy to clean coating stain The removal effect is about 10 times that of ordinary coating.

2. The four corners of the furnace wall and the surrounding places connecting with the furnace door should always be kept clean. if there be Cleaning agent Or food scraps and oil stains left on hinge And the door seam can be wiped off with a damp cloth dipped with some neutral detergent. Do not use abrasive cloth or Rough zone Causing injury by wiping with corrosive detergent or scraping with a knife Furnace wall Metal of Protective layer 。 If the microwave oven is not wiped immediately after use, it is easy to form inside Oil stain So we have to use a special way to remove the scale: put a cup of water into the oven, boil it for 2 to 3 minutes, and let the microwave oven be filled with steam, so that the stubborn scale will become soft and easy to remove due to full water.

3. If there is peculiar smell in the furnace, put a cup of water into the furnace and add a tablespoon lemon juice or vinegar , hot for 2-3 minutes, remove the cup and wipe it clean, the odor will be eliminated.

4. The outer wall of the oven should be cleaned regularly to remove the oil stain caused by daily cooking, so as not to reduce the efficiency of the microwave oven.

5. The furnace should always be kept clean. After disconnecting the power supply, use a damp cloth and Neutral detergent Wipe, do not wash, do not let water flow into the electrical appliances in the furnace.

When cleaning the internal cavity of the microwave oven, do not miss the yellow rectangular mica piece on the right side of the internal cavity. Its quality directly affects the function and service life of the microwave oven. If the mica sheet is seriously polluted or even broken down, it may also cause Short circuit Causes various hazards.

Other details

Microwave oven warning

1. Before using the microwave oven, carefully read the operating instructions provided by the manufacturer, know your microwave oven, and accept the instructions.

2. If the power supply is insufficient, the light in the furnace will appear dim. At this time, if you continue to use it, the safety equipment will be damaged, and it should be stopped immediately.

3. The microwave oven should be placed in a ventilated place. There should be no microwave oven nearby Magnetic material So as not to interfere with the uniform state of the magnetic field in the furnace cavity work efficiency Down. The microwave oven should be placed horizontally, away from the fire and water tap 。 Do not cover the ventilation places behind the furnace or on both sides. It is better to keep a distance of at least 5cm (2in) from the wall so that the hot gas can be easily distributed. It is also necessary to keep a certain distance from the TV and radio, otherwise the visual and listening effects will be affected.

4. Do not use the microwave oven if it is empty. Because the emitted microwave cannot be absorbed, it will bounce back to the magnetron and be damaged.

If there are children at home (especially Preschool children ）Or Mental retardation Family members of No load operation , a glass containing water can be built in the furnace cavity; The best option is that the microwave oven is controlled by an independent power switch to avoid unforeseen catastrophic consequences to the greatest extent.

5. When using a turntable microwave oven, the food container must be placed on a special plate for the microwave oven, not directly in the oven cavity.

6. Be sure to close it fire door , ensure that the interlock switch and Safety switch Closure of. When the microwave oven is turned off, food should not be taken out immediately. Therefore, there is still residual heat in the oven. Food can still be cooked. It should be taken out after 1 minute.

7. If the microwave oven door has Dent Or it should not be used if there is any damage that causes it to be loose. Regular inspection If there is damage or poor closing around the door and door lock, stop using to prevent microwave leakage. If the door hinge is found to be improper, someone should repair it immediately. Do not put your face close to the observation window of the microwave oven to prevent your eyes from microwave radiation And be damaged. It should not be exposed to microwave irradiation for a long time to prevent dizzy , dizziness, fatigue, emaciation, hair loss and other symptoms, causing human damage.

8. Most microwave ovens have a microwave feed inlet on the right side of the oven cavity, which is generally used mica Or plastic sheet, it must be cleaned with wet cloth regularly (it is recommended to use the microwave oven for about 10 times), otherwise the oil stain or food residue splashed on it is easy to be carbonized, causing microwave reflection and burning the magnetron.

In the process of heating food, it is best to cover the food with a ceramic or glass plate, which can prevent lampblack Or food scraps splash and reduce water vapor adhesion to the inner wall, which can also avoid the safety hazards of the microwave oven, and also reduce the cleaning workload.

9. Do not leave food scraps or oil stains at the crack of the door or the opening of the door, so that the furnace door cannot be closed tightly.

10. The microwave oven should always be kept clean and dry. If there is moisture in the oven that will reduce the efficiency, try to wipe it dry.

11. If metal is attached to the whole bag of food Clip , it should be removed first, and the metal strip of the plastic cooking bag should not be used. If sparks occur in the furnace, immediately Shutdown 。

12. If the microwave oven catches fire accidentally, do not open the oven door. Press the button to turn off the oven first, and then pull out the plug. The fire in the oven will go out slowly.

13. Even when frying the food with shell (such as the whole egg, which will burst in the furnace due to pressure), the shell should be punctured with a needle or chopsticks in advance to avoid bursting, splashing and polluting the furnace wall, or splashing and injuring people after heating. Whole leather vegetable & fruit Such as potato seeds Melon 、 tomato and Plum The skin shall be punctured to drain gas to avoid explosion. sausage 、 Chicken liver , egg yolk Fresh fish Poultry eyes should also be punctured. When heating milk or soup, it is best to stir it halfway to avoid overflow. If you want to cook pasta in the microwave oven, do not add oil in the water, because the oil floating on the water will splash when heated, causing danger.

Power saving skills

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1、 The microwave oven is not easy to stain the food surface. You can put flavoring Apply it on the food surface to make it dark brown.

2、 The food heated by microwave oven is extremely hot and easy to evaporate water. It should be covered with heat resistant material when cooking Fresh keeping film or Temperature resistant glass Cover to keep moisture. Chicken wing tip 、 Chicken breast Or fish head, fish tail or corner of cake, which are easy to overcook Aluminum foil paper Covering can achieve uniform cooking.

3、 At the end of heating, put food aside for a period of time or add some food Seasoning (For example, after cooking poultry meat, it can be poured with emulsified oil or Sauce Spread some more cayenne pepper 、 crumbs And so on), which can achieve satisfactory results that cannot be achieved by heating.

4、 The food should be evenly arranged, not piled up in a pile, so that the food can generate heat evenly. Small pieces of food mature faster than large pieces of food. It's better to cut the food into small pieces less than 5cm. Food shape The more regular, the more uniform the microwave heating. Generally, The The food is cut into pieces or pieces of suitable size and uniform shape.

5、 If the food has a hard skin, it must be peeled off before cooking.

6、 The higher the temperature of the food itself, Cooking time The shorter; summer heating time It is shorter than in winter. Cooking thick and dense food with more pores takes a long time to heat. Foods with high water content are generally easy to absorb more microwaves, and the cooking time is shorter than those with low water content.

7、 When cooking food in the microwave, it is better to undercook than overcook. Microwave re cooking will not affect the color, aroma and taste of dishes.

8、 When cooking in the microwave oven, the amount of salt should be reduced as far as possible, so as to avoid cooking food that is cooked outside and raw inside.

Cooking Instructions

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Heat according to food properties

food Initial temperature 。 The higher the temperature of the food itself, the shorter the cooking time; Heating time is shorter in summer than in winter.

Adjustment of food quantity. The amount of food is proportional to the heating time. The more food, the longer the heating time.

Food density and water content 。

Microwave cooking

Container selection and food arrangement

Generally speaking, it is shallow and round Straight edge The container containing food should be heated quickly and evenly, so it should be preferred. Because the microwave heats the surrounding food quickly, the thick part should be arranged outward, and the small part should be arranged in the middle of the container and placed radially on the plate, so that the thick part that is not easy to be cooked can absorb more microwave energy.

Fault inspection

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Warm prompt: professional maintenance personnel are recommended.

When the microwave oven is in use, the power supply is just connected, Fuse That is, fusing fault. The troubleshooting method is introduced.

Microwave oven circuit is divided into power control system and high-voltage system. During maintenance, the high-voltage transformer can be used as the boundary, and the secondary circuit can be disconnected first, so as to quickly determine the fault location and ensure the safety of maintenance.

First open the microwave oven shell, find the high-voltage transformer and High voltage capacitor , because the secondary circuit is used Connector So it is very convenient to just unplug the plug-in. At this time, when the replacement fuse is energized, the following two conditions will occur.

(1) The fan and tray operate normally after power on. This indicates that the power control system and transformer are in good condition, and the fault is in the high-voltage system. Continue to check the high pressure capacitor and High voltage silicon stack If the high-voltage capacitor is found to have broken down, it means that the fuse in the machine is broken because of the secondary of the transformer short-circuit current Too large. After the capacitor of the same specification is replaced, the fault can be eliminated.

(2) Inside the machine after power on Fuse Burn out again. From this, it can be judged that the high-voltage circuit system is normal, and the fault occurs in the transformer itself or the power control circuit. Plug in at one end of the primary circuit of the transformer can be unplugged. If the fan and tray operate normally after power on, the transformer is damaged. Cause of fault Probably transformer winding Turn to turn short circuit can be eliminated by replacing the transformer. If the fuse in the motor is still blown after unplugging the plug-in of the transformer primary circuit, the fault must occur in the power control system. The fault may be caused by interlock switch Monitoring switch Damage power cord Or the wire is seriously leaked or even short circuited. As long as these components pass simple inspection, the fault can be found. After the components are removed or replaced, the microwave oven can resume normal operation.

Maintenance skills

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Self repair

Microwave Oven Mica sheet Maintenance and replacement Common sense

In the daily use of microwave oven, it is necessary to clean the mica frequently to keep it clean and dry. The mica cannot be cleaned or has been broken down due to serious pollution Black spot It must be replaced in time. Users with strong hands-on ability can operate it by themselves to ensure the key components of the microwave oven“ Magnetron ”Not damaged.

The steps for replacing mica flakes are as follows:

1. Prepare a new mica sheet. In a treasure Business platform You can buy special microwave ovens at a very low price.

2. Remove the old mica sheet.

The removal methods of mica pieces with different fixing methods: the removal of the card slot is the simplest, without any tools, just carefully and forcefully pull it from bottom to top, bend the mica piece slightly at the protruding part of the inner cavity, and then continue to push it upward to remove it; If it is locked by plastic stopper, use bolt driver The plug pin can be easily removed by prying it out.

3. Use paper towels or Duster cloth Clean microwave Launch window 。

4. Use scissors to cut a new prepared mica sheet compared with the old one (because the new mica sheet is larger).

5. Install the cut new mica pieces in the reverse order of disassembly. If it is fixed with a stopper pin, it can be pressed into the hole on the microwave transmission window with force.

It is suggested that the mica sheet is brittle and easy to break if it is excessively bent.

New Mica for Microwave Oven

If the mica chip burns through and ignites after the microwave oven is powered on, this is often a fault in the magnetron, which needs to be repaired by professional personnel.

Professional maintenance

First, before disassembly and maintenance, safety related parts and components must be checked, mainly to fire door Whether it can be tightly closed, whether the door gap is too large, whether the observation window is broken, whether the Solder joint Whether there is desoldering, whether the furnace door sealing gasket is damaged and uneven. This is mainly to check whether there is the possibility of excessive microwave leakage. If problems are found, they should be repaired first; If it cannot be repaired temporarily due to lack of parts or other reasons, other faults in the machine can be repaired first, but after other faults are repaired, do not force to use it, let alone deliver it to the user, and delivery can only be made after the safety hazards are completely eliminated.

Second, if you need to check the machine Internal circuit , usually the microwave oven should be disassembled after the power is cut off. After disassembly, use plastic insulation handle first Screwdriver take High voltage capacitor Short circuit discharge at both ends to avoid electric shock during maintenance. This is because after the microwave oven is powered off, there may still be a high voltage on the high-voltage capacitor, especially after the power failure stove Even more so, do not think it will be safe after power failure.

Third, in addition to measuring 220V Mains electricity In addition to voltage inspection, if you are not sure about it, you should try not to conduct power on inspection. If power on inspection is really required, it must be disconnected first High voltage circuit , do not let the magnetron work, and then turn on the machine for inspection to ensure that Personal safety 。 As for the inspection of magnetron and its power supply circuit, unless you have the necessary professional maintenance equipment knowledge and experience, you should use the power off inspection method to ensure safety. Practice shows that as long as the relevant skills are mastered, the power off inspection is not much worse than the power on inspection, and the speed of judging some faults is even better than the power on inspection.

Fourth, when parts need to be disassembled for inspection or replacement during maintenance, remember the original position of the disassembled parts one by one, especially the parts of the safety mechanism and high-voltage circuit, and place them after disassembly to prevent loss and unnecessary trouble; During reassembly, it shall be accurately reset and installed one by one, and each fastening screw and other fasteners shall be tightened. Do not install incorrectly or omit to install small parts that are easy to be ignored, such as washers. If parts need to be replaced, try to select the parts with prototype number. If not, the replacement parts with similar characteristics and installation dimensions can be used.

Fifth, after the maintenance is completed and all parts are installed, check whether the furnace door can be opened and closed flexibly again, and pay attention to the door gap Doormat and Observation window If there is any abnormal condition, and if the adjusting buttons, switches and other parts are normal, it can be used until it is confirmed that there is no problem.

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