An irreplaceable assistant in the kitchen is a microwave. The principle of operation of a microwave oven and a variety of models

Microwave ovens have become as commonplace as ovens and gas stoves. Despite the outward similarity of all microwaves, their "stuffing" is different. Many manufacturers offer microwave ovens with grills, convectors and other functional elements.

Before you start choosing, decide what you need a microwave oven for. Do you want to cook in it fine dining or plan to limit yourself to only heating and defrosting food. Let's talk about everything in more detail.

Principle of operation

Principle of operation microwave oven simple and complex at the same time. Consumers often do not know how food is heated. Some have heard about some kind of radiation and therefore try to bypass microwave ovens in order to avoid health problems.

Let's start with the fact that microwave radiation does not affect a person in any way. Microwaves occupy a position on the frequency scale between radio waves and infrared radiation, and even have properties inherent in both. It is known that neither heat nor radio waves cause damage to our health, therefore, microwaves cannot do this either.

How does a microwave heat up food? Microwaves set the water molecules in food in motion. They begin to move randomly, thereby generating energy, which means heat.

Types of microwave ovens

With all the variety of microwave ovens on the market, they can be divided into 4 main types, which we will consider:

Solo (only microwaves);

With grill (microwaves + grill);

With grill and convection (microwaves + grill + convection);

With grill, convection and steam generator (microwaves + grill + convection + steam).

Starting to choose a microwave, decide why you need it in culinary terms. If only for heating food and defrosting, then you should pay attention to the “solo oven”. By the way, do not underestimate this type of microwave ovens and limit their functionality to only banal heating / defrosting. In the microwave with microwave function, you can cook wonderful desserts and culinary dishes.

A microwave oven with a grill and a microwave function is suitable for lovers of well-roasted meat. The grill built into the oven can be a heating element. It looks like a metal tube, a spiral, with a heating element inside. Also, quartz grills are built into microwave ovens, which are a tightly twisted wire made of a heat-resistant alloy of nickel and chromium, which is placed in a quartz glass tube. The heating element grill is located in the upper part of the working chamber of the microwave oven. In some models of ovens, the grill is movable, within the framework of the working chamber, it can be installed where you need it. With such a grill, evenly roasted meat is not a problem.

Quartz grill - fixed, it is placed on the "ceiling" of the working chamber. Such a grill heats up faster, is more economical, it is easier to clean, because it is not complex shape, like a heating element. Some models are equipped with both types of grills at once: “upper” quartz and “lower” heating elements. Thanks to the presence of this function, dishes can be browned.

As practice shows, people who are passionate about cooking and have already mastered microwave ovens with a grill function are unable to resist the temptation to purchase a device with a grill and convection.

The principle of convection is simple. In fact, this is a fan built into the microwave that drives hot air through the working chamber. Thanks to this, the dish is baked evenly. The microwave function is used to speed up the cooking process. At the finish, the grill is connected to brown the dish again. As a result, the cooking time in such an oven is greatly reduced, while the quality is increased.

There are also microwave ovens with microwave, grill, confection and steam functions. The presence of a double boiler, of course, can please the adept healthy lifestyle life, however, buns and baked meat in this case will have to move. Apparently, therefore, “advanced” users do not have a single opinion on their account.

As for the quality of cooking, a few years ago, microwaves had a significant problem. This was due to the fact that only one microwave emitter was installed in them, therefore, microwaves were distributed unevenly over the working chamber and the dishes remained partially raw. This steadily reduced consumer confidence in microwave ovens, so they were only bought for heating food. However, over time, the problem was resolved. In modern ovens, manufacturers provide two or even three sources of microwave radiation that emit beams of waves in different directions, and, reflected from the walls, are evenly distributed throughout the working chamber of the oven, so food is cooked evenly.

Volume

Before buying, you also need to decide on the capacity of the microwave oven. Think about what culinary feats you want to accomplish with this device. The volume of the working chamber of the microwave oven can be different - from 13 to 42 liters. Ovens up to 20 liters are enough for heating / defrosting and cooking everyone's favorite grilled chicken. For big family take a stove with a chamber volume of 23 to 32 liters. If you have to cook a lot, then take a closer look at stoves with a chamber volume of 40 liters or more.

Power

Power, as elsewhere, is one of the main characteristics of the device. It depends on her how quickly food will be cooked, heated or defrosted. Usually, the larger the microwave, the higher its power. By the way, almost all microwave ovens have a power regulator, even the simplest ones.

The power of microwaves in most microwaves is 700-1000 watts. And that only applies to microwaves. If you're considering purchasing a convection grill oven, make sure your home's electrical wiring is in order. The fact is that with the simultaneous operation of all these modes, their powers add up.

That is, if the microwave power of your microwave is 900 watts, the grill is 1200 watts, and the convection is 1350 watts, this means that the total power of your microwave will be 3450 watts. And this is already a serious load, even without taking into account other electrical appliances working in the apartment.

Previously, the power of microwaves was not regulated in any way. That is, in the "old" ovens, the microwave emitter periodically turned off for a few seconds, then turned on again, which led to the fact that the dish turned out to be dry, because excessive exposure to water molecules in the active phase of the emitter operation leads to its evaporation. Manufacturers decided to change the very principle of microwave power control and began to use inverter control. In new ovens, the power of the microwave emitter decreased and increased smoothly, while the oven did not turn off at all. The product was thus subjected to continuous gentle exposure to microwaves, retaining its properties.

Functions

Using a modern microwave oven in the kitchen, you get the opportunity to cook, fry, steam and bake. We emphasize that you have the opportunity. Because the ovens have various functions designed to help you prepare your meals.

For example, "Automatic cooking" is the recipes for cooking dishes entered in the memory of the microwave oven. Of course, we are talking just about the algorithms of the furnace. So that the user does not suffer from fine tuning microwave, grill or convection, manufacturers have provided cooking templates. For example, grilled chicken will turn out with a 100% probability if you use the automatic cooking option, trusting the manufacturer's preset settings. Usually microwave ovens have 4-8 preset recipes, but there can be many more, and in some ovens such settings can be entered independently.

You can also defrost food simply, not in automatic mode. Then the user himself sets the defrost time. However, this often leads to the fact that an incorrectly set power, coupled with an excessive defrosting time for a given product, spoils the product. Not thawed from the inside, it begins to fry from above. Therefore, it is safer to still use the "machine".

The function "Automatic heating" is known to all users of microwave ovens. The algorithm is the same as for the auto-defrost function. Choose the type of product, its weight and click on the "Start" button. The microwave will independently determine how much time it needs to warm up, and at what power it will do it. There can be up to 25 “recipes” for auto-heating.

The Microwave + Grill mode is a favorite of many users, because the dishes are evenly fried and with a golden crust.

In the "Microwave + Convection" mode, food is cooked faster. "Grill + Convection" - a mode for cooking fried foods, as well as baking.

Some microwave ovens have a "Crisp" function. The furnace is supplied with a special plate, which is made of a material based on ferrite. It converts microwave energy into heat. There is an impact on the product from below, and it is fried.

The "Steam Oven Clean" program is only available on units with a steam generator. Steam dissolves grease and dirt left after cooking. The user pours water into a special container built into the stove, adds detergent and activates the program by pressing a button. After 10-15 minutes, the microwave becomes clean.

The function of removing odors is provided by microwave manufacturers in case users need to weather the consequences of cooking strong-smelling foods. To do this, a fan is built into the oven.

Included in the microwave are usually additional accessories: grills, skewer, trays, plastic dishes, coasters for baby bottles, a container for baking bread, utensils for steaming dishes. If the package does not contain what you need, stock up on utensils designed specifically for use in a microwave oven. And remember the main rule of using a microwave oven - no metal! Metal rims on cups and plates will spark and cause damage to the oven.

If the question of how a microwave oven works comes to your mind, then it will not be difficult to answer it, because this device is on the market. household appliances for a long time and its characteristics have been studied up and down. The principle of operation of a microwave oven is based on the effect of microwaves on the product placed inside the device. Details about what a microwave oven and microwave are will be discussed below.

The operation of devices of this type is based on the transformation of the so-called electromagnetic microwave fields. A similar field is transformed in thermal energy and warms up the food in the chamber. The principle of operation of a microwave oven differs from other devices for cooking: ovens (both gas and electric, where heating occurs due to the elementary heating of the contact surface and the surrounding space in the chamber) and stoves.

The principle of operation of the microwave oven allows you to heat only the object itself, placed inside. Therefore, the process of heating food is quite fast. At one time, it was this advantage that allowed the microwave oven to gain popularity and confidently take a leading position in the market. kitchen appliances. To defrost or reheat a cooked dish, it was no longer necessary to expend extra energy (for heating the entire chamber). In a few minutes, the electric wave action raised the temperature to the required level. For example, a piece of frozen meat was ready for cutting and further cooking without a long wait.

Traditional types of thermal exposure work a little differently. Heat is supplied to the surface heated object, as a result of which quite often one can observe such a picture when outer side The defrosted dish has already crusted and started to burn, but inside it remains frozen. This is due to the fact that the heating occurs unevenly, the heat is distributed vertically: from the upper layer to the inner one. This method is much less efficient than the operation of a microwave oven, moreover, it requires certain skill and culinary skills from the owner, while cooking in a microwave oven is enough just press a couple of buttons and expect results.

The electrical circuit of the microwave oven has remained unchanged since the launch of the device in mass production. Changed to meet current requirements appearance, devices have become more aesthetically attractive. A lot of hardware functions have been added, more comfortable methods of control, regulation of the power of exposure, but the principle itself has remained the same as 50 years ago. This is connected not only with famous saying“why change what works so well”, just the principle itself does not imply any radical changes.

By the way, when it comes to microwave and microwave ovens, it should be remembered that these concepts are identical, these devices are not different types devices, as it may seem to someone at first glance.

A couple of decades ago, a microwave oven was a luxury item and was more likely to be present in the kitchen as an element of decor, rather than being an item for everyday use. Of course, over time, manufacturing techniques became more accessible to the mass market, which led to the wide availability of microwaves and their ubiquity. So, from a luxury item and a rare technological curiosity, the microwave oven has become an indispensable assistant in the kitchen, capable of preparing simple meals in a matter of moments.

A few words about heating

The microwave oven device includes the so-called. This definition should be familiar to anyone who knows how radar works and works.

The microwave oven, as a mechanical device, is able to quickly heat food precisely thanks to the magnetron.

If we consider the electrical circuit of a microwave oven (for example, Samsung) from the inside, it becomes clear that these developments have migrated to the segment of household appliances from heavy industry. Different kinds devices differ only externally. So, for example, the LG microwave circuit will not differ much from the Daewoo brand microwave circuit.

This is how a microwave oven works: the magnetron begins to release energy during operation, which is converted into heat and used as targeted heating. This type The device is powered by an anode-filament transformer-stabilizer. At first, this particular part was the most expensive in the production of microwaves. But over time, its cost fell to an acceptable level, which made it possible to mass-produce devices.

Considering the internal structure of the microwave, it is worth considering the design in more detail. shunt magnetic circuit. This unit allows you to change the voltage increase within an error of 2% within a 10% power grid fluctuation. Main Feature transformer is high strength inductive leakage of the magnetic circuit. It may be that in words the description of the principle of operation of a microwave oven looks somewhat complicated, but in practice the device is quite simple.

At the time of the start of the design, design engineers were faced with increased level noise during microwave operation. In general, it is worth mentioning that high level Noise is a problem with many devices based on a heat dissipation or cooling unit. Subsequently, this problem, of course, was solved, and rather interesting way. For elimination increased vibration some parts were joined by welding.

The microwave device begins first of all with the body. In most cases, it is rectangular box. This was done not because designers suffer from a lack of imagination, the point here is in the specifics of operation.

When the microwave is turned on, the waves are not only directed towards the object being heated, they are also reflected from interior decoration housing, which significantly increases the thermal effect.

Also, the rotating part - the saucer - allows you to optimize the heating process. As it rotates, the waves are distributed evenly over the entire surface of the heated object. A wave entering a tank with products always has different shape - this is another specific feature of microwave ovens. Some waves are nodal, others are formed in the form of beams, so the impact is chaotic in nature, but optimization measures make it possible to level this process.

Over the entire history of the existence of this type of device, the process of their manufacture, thermal exposure and its optimization have been perfected by manufacturers to perfect condition. To date, the microwave oven is a complete device, completely ready for use, reliable and safe, which is confirmed by many certificates of international monitoring consortiums that regulate harmful effect technology on the human body.

An important function of the microwave oven door

No less attention during production is given to the door. In microwave ovens, the door is not only decorative element, but also serves as a kind of fuse. The principle is very simple: if you open the door, the lock is activated and the operation of the units stops. Despite the apparent simplicity, the device of the door is quite difficult, because it is connected with safe operation the entire apparatus.

So, let's take a closer look at how the microwave oven door works:

• Firstly, the manufacturer needs to ensure that the door and body of the device fit perfectly with each other with a minimum angle. Large gaps prevent the device from being used. The reason is simple, the door serves a kind shield from microwave radiation , and if the gap is large enough, the radiation may penetrate outside the cooking chamber. It has long been known what radiation is and what its danger is.
• Secondly, the perimeter of the door is equipped with a high frequency throttle. This device serves to reduce radiation to an acceptable level.
• Thirdly, at the time of casting the door body, a lot of additives are added, with the help of which a high percentage of radiation absorption is achieved. Of course, one cannot be completely sure of 100% absorption of radiation, but there is no doubt that the residual waves do not pose a danger and significant harm to human health.

In the entire history of the existence of the device, this part of the microwave has not undergone any major changes. In general, it is always two handles, one of which is responsible for the temperature, and the other for the cooking time. Of course, today you can find many differences in modifications: from simple "wheels" to control units, which will have many different functions. That's just the essence of them, often comes down to an old and proven principle, nothing new in the device microwave ovens for all the time of their existence is not invented. The fundamental difference can only be in the concept of controlling the device.

Now many manufacturers (for example, Samsung) are betting on the innovative component and integrating touch control panels into their microwave ovens.

A little about the dangers of microwaves

Disputes about do not subside from the moment they are launched into mass production. To date, there is no reliable information confirming the harm from using this type of device.

Do not forget that the microwave does not emit radioactive waves. On the contrary, the microwave oven allows you to cook food without losing it. useful properties. Food is healthier because it retains up to 80% of vitamins and minerals.

Traditional ovens and stoves cannot boast of such a result. If you operate the device clearly according to the rules, then there is no danger from its operation. This conclusion is also confirmed by the way the microwave oven is arranged, as mentioned above.

Harm may not healthy food cooked in a microwave oven (the so-called fast food), and thermal microwave exposure has nothing to do with it. The harm of pies (and other flour products) lies not in the fact that they are cooked in the oven, but in their high calorie content and slow absorption by the body.

The frequency of your microwave, which is also mentioned when it comes to harm, also does not play any significant role. It (frequency) can change as much as you like, but this (contrary to popular belief) will not lead to an increase or decrease in radiation, the background remains the same.

Conclusion

The conclusion that suggests itself: a microwave oven is a very simple, but at the same time indispensable device in the kitchen, which makes our life easier every day. It is convenient and unpretentious in use and maintenance, easy to clean, takes up little space and consumes very little energy. The microwave device, as discussed above, remained unchanged: a magnetron, an I/O transformer, an I/O capacitor, a cooler, and a cooking chamber. The reliability of this technique has been proven in practice for several decades.

The first to discover the possibility of microwave radiation to heat food was American engineer Percy Spencer. It is he and patented the microwave.

Judging from the stories of eyewitnesses, the idea of ​​its creation came to him when he stood for several hours near the magnetron and found a piece of chocolate melted in his pocket.

The device is capable of heating food without heat energy and this is more like a radio transmitter than the one we are used to. cooker. The main active element is Microwaves are one of the forms electromagnetic energy like light and radio waves.

At the speed of light they propagate towards the object in the form of microwave waves, the length of which varies from 0.01 to 1 m.

REFERENCE! Microwave microwaves are also used in civil radar, radio navigation, satellite television, mobile communications, etc. Microwaves in natural environment emitted by the sun and measured with certain instruments.

Microwave device

How is a microwave oven made? An oven with a control panel, a waveguide, a turntable, a transformer, a capacitor and a magnetron are the main elements of building a microwave oven.

The scheme of operation of the microwave oven is as follows: from the control panel electricity enters the transformer, then into the capacitor, where the power is increased and transferred to the magnetron.

IMPORTANT! A high voltage is applied to the filament(about 3-4 kW) so that its antenna can radiate quite strong microwave waves.

Interacting with water molecules in food an electromagnetic field with a frequency of 2450 MHz is converted by a waveguide contained in any microwave oven.

Thermal fuses or thermal relays serve to ensure the safety of the device and prevent it from overheating.

The principle of the fuse is very simple. In the place where it is necessary to control the temperature, its aluminum body is attached using a special flange connection. Thus, maximum thermal contact is ensured. Metal plate, located inside the thermal relay, is fundamentally tuned to a specific temperature.

Microwaves also equipped with fans, which suck in air from the outside, and then distribute it inside the case through the blower through the ventilation system. The fan motor is a conventional single-phase asynchronous motor alternating current.

IMPORTANT! To avoid turning on an open microwave, a system of three microswitches is provided. One of them turns off the magnetron. The next one turns on the backlight. And the third is designed to notify the control unit about the opening of the door.

To the main functions of the control unit can be attributed:

• regulation of the power of the device;
• automatic shutdown after the programmed time has elapsed.

How does a microwave oven work

Since the microwaves that the oven produces affect precisely the water molecules. In other words, all that is needed is the content of a small amount of water in the food located in the chamber.

Increasing food temperature in the oven, under the action of microwaves, it resembles the process when hands are warmed up if we rub them strongly. The similarity also lies in the fact that when one palm rubs against the surface of the other, heat seeps into soft tissues. Microwaves work on the same principle. on a small surface (1–3 cm), without penetrating deep into the object.

The emitted microwaves come into contact with water molecules, causing them to move faster and warm up the food. There are millions of molecules in a drop of water, and when a microbeam hits them, it penetrates the food to a depth of 2.5 cm, causing them to sway under the action of electromagnetic field. During this friction, heat is released.

In this way, foods with a high liquid content heat up faster.

IMPORTANT! Until now, scientists are arguing how harmful the microwave is and how it affects the quality of food. but World Health Organization States that Microwave ovens do not harm anyone nor on the food consumed.

How advanced microwave functions work

Almost all modern ovens have grill mode. When not only the chamber is heated inside, but also heat is supplied with the help of a special awning - a curved metal device located at the top of the chamber. They are called heating elements - from "thermal electric heater".

In modern ovens, in addition to the grill mode, there is convection mode. When the chamber is effectively blown from the grill heating element to the food. The system is a circulator. Convective heat transfer, in relation to a furnace, is the transfer of heat with the help of air molecules. The use of a fan is what is commonly referred to as convection mode.

Modern models have a number of recipes and cooking methods built into the computer.

A power of 500 - 700 watts is enough. The higher the power, the faster the dish will heat up, but more energy will be spent. Models with grill and convection should be more powerful - from 1000 W, and the volume of the chamber of such a microwave oven should be 30 liters or more.

Volume

A small microwave oven with a volume of up to 17 liters will be enough to heat food. To prepare full meal, for example, bake a chicken, this volume is not enough, the carcass simply will not enter it. It should be borne in mind that in a heating element microwave oven, the usable volume will be slightly less than indicated in the characteristics, since part of the chamber is occupied a heating element grill. This does not apply to quartz microwave ovens, as they have a heating element built into upper part cameras, and the entire specified volume will be useful. For a family of 3 people, the volume of the microwave oven should be at least 17 liters, and preferably from 25 liters. For those who cook in large portions, models with a volume of 30 liters or more are suitable.

Coating

Enamel, ceramics, bioceramics and stainless steel are used as coatings for the chambers. Stainless steel chambers are more suitable for heating and cooking, as it will be difficult to wash them of burnt fat: metal scrapers will leave scratches, and abrasive cleaners cannot be used. For office and summer cottages, you can purchase a stove with an enamelled chamber surface. If you plan to use the microwave often, baking in it, including fatty foods, better model with a ceramic or bio-ceramic coating, as it is the easiest to clean.

Control

There are two types of control: mechanical and electronic.

The mechanical type of control is simple and reliable, usually there are two regulators here - time and power. Microwaves with multiple modes are electronically controlled. Using the buttons or touching the sensor, programs are set, the temperature and cooking time are selected. The touch panel is easier to care for than the keypad, as there are no protruding elements on it. It is enough to wipe the panel with a damp cloth, having previously disconnected the device from the mains.

Microwave ovens (MW ovens) have long been the most common household appliance, with which you can quickly defrost food, reheat already cooked food or cook a dish according to original recipe, and even disinfect metal-free kitchen cleaning sponges and cloths.

The presence of a convenient, intuitive interface, as well as multi-level protection, allows even a child to cope with the management of such a complex and high-tech device as a microwave oven. Some dishes can be easily and quickly prepared using built-in programs. BUT possible faults it is quite possible to eliminate by doing .

The heating of products placed in the microwave chamber occurs due to the impact on them of a powerful electromagnetic radiation decimeter range. IN household appliances use a frequency of 2450 MHz. Radio waves of such a high frequency penetrate deep into the products, and act on polar molecules (in products it is mainly water), forcing them to constantly shift and line up along lines of force electromagnetic field.

Such a movement raises the temperature of the products, and the heating goes not only from the outside, but also to the depth to which radio waves penetrate. In household microwave ovens, waves penetrate 2.5-3 cm deep, they heat the water, and that, in turn, the entire volume of products.

Magnetron device - the main component

Radio waves with a frequency of 2450 MHz are generated by a special device - magnetron, which is an electrovacuum diode. It has a massive copper cylindrical anode, round in cross section and divided into 10 sectors with the same copper walls.

In the center of this design is a rod cathode, inside of which there is a filament. The cathode serves to emit electrons. Powerful ring magnets are located along the ends of the magnetron, which creates a magnetic field inside the magnetron, which is necessary for generating microwave radiation.

A voltage of 4000 volts is applied to the anode, and 3 volts to the filament. There is an intense emission of electrons, which are picked up electric field high tension. The geometry of the resonator chambers and the anode voltage determine the generated frequency of the magnetron.

The energy is removed by means of a wire loop connected to the cathode and led out to the emitter-antenna. From the antenna, microwave radiation enters the waveguide, and from it into the microwave chamber. The standard output power of magnetrons used in domestic microwave ovens is 800 watts.

If less power is required for cooking, then this is achieved by turning on the magnetron for certain periods of time, followed by a pause.

To obtain a power of 400 W (or 50% of the output power), you can turn on the magnetron for 5 seconds within a 10-second interval and turn it off for 5 seconds. In science it's called pulse width modulation.

The magnetron emits a large number of heat, so its body is placed in a plate radiator, which during operation should always be blown by air from the fan built into the microwave. When overheated, the magnetron very often fails, so it is equipped with protection - a thermal fuse.

Thermal fuse and why you need it

To protect the magnetron from overheating, as well as the grill, which some models of microwave ovens are equipped with, special devices are used, called thermal fuse or thermal relay. They are available in different temperature ratings indicated on their body.

The principle of operation of the thermostat is very simple. Its aluminum body is flanged to the place where the temperature needs to be controlled. This ensures reliable thermal contact. Inside the thermal fuse is a bimetallic plate that has settings for a certain temperature.

When the temperature threshold is exceeded, the plate bends and actuates the pusher, which opens the plates contact group. Microwave power is interrupted. After cooling, the geometry of the bimetallic plate is restored and the contacts are closed.

Purpose of microwave oven fans

The fan is the most important component of any microwave oven, without which its operation will be impossible. It performs a number of important functions:

• Firstly, the fan blows over the main part of the microwave oven - the magnetron, ensuring its normal operation.
• Secondly, other components of the electronic circuit also generate heat and require ventilation.
• Thirdly, some microwave ovens are equipped with a grill that is necessarily ventilated and protected by a thermostat.
• And, finally, in the chamber, the cooked products also emit a large amount of heat and water vapor. The fan creates a small overpressure, as a result of which the air from the chamber, together with the heated water vapor, escapes through special ventilation openings.

In the microwave from one fan, which is located at rear wall housing and sucks in air from the outside, a ventilation system is organized using air ducts, directing the air flow to the magnetron plates, and then into the chamber. The fan motor is a simple single-phase AC motor.

Microwave protection and locking system

Any microwave oven has inside a powerful radio-emitting device - a magnetron. Microwave radiation of this power can cause irreparable harm human health and all living beings, therefore, it is necessary to take a number of measures to protect.

The microwave has a fully shielded metal working chamber, which is additionally protected from the outside metal case, which does not allow high-frequency radiation to penetrate outside.

The transparent glass in the door has a screen made of metal mesh with a small cell that does not let out radiation of 2450 Hz, a wavelength of 12.2 cm, generated by a magnetron.

The issue of saving energy consumption has always been relevant. one of the types lighting fixtures, which will greatly help reduce household electricity consumption, are. To do optimal choice, you just need to understand the advantages and disadvantages of each type of such lamps.

Double switches in view of their features are widely used in the home. How to connect such switches correctly and what you need to know to prevent errors in this case can be read in.

Microwave door fits snugly into cabinet and it is very important that this gap retains its geometric dimensions. The distance between the metal case of the chamber and the special groove of the door should be equal to a quarter of the wavelength of microwave radiation: 12.2 cm/4=3.05 cm.

In this gap, a standing electromagnetic wave, which exactly at the place where the door touches the body has a zero amplitude value, so the wave does not propagate outward. In such an elegant way, the issue of protection against microwave radiation is solved with the help of microwave waves themselves. This method of protection in science is called a microwave choke.

To prevent the microwave oven from turning on with an open chamber there is a system of microswitches that control the position of the door. Usually there are at least three such switches: one turns off the magnetron, the other turns on the backlight even when the magnetron is not working, and the third serves to “inform” the control unit about the position of the door.

The microswitches are positioned and configured so that they only operate when the oven chamber is closed.

Microswitches on the door are also often referred to as limit switches.

The control unit is the brain of the device

Any microwave oven has a control unit and it performs two main functions:

• Maintaining the set power of the microwave oven.
• Turn off the oven after the set operating time has elapsed.

On older models of electric furnaces, the control unit was represented by two electromechanical switches, one of which just set the power, and the other the time interval. With the development of digital technologies, electronic control units began to be used, and now microprocessor ones, which, in addition to performing two main functions, can also include many necessary and unnecessary service ones.

• Built-in clock, which can certainly be useful.
• Power level indication.
• Changing the power level using the keyboard (button or touch).
• Cooking or defrosting food using special programs "hardwired" into the memory of the control unit. In this case, weight is taken into account, and the oven will select the required power itself.
• Signaling the end of the program by the selected soundtrack.

In addition, at modern models there are upper and lower grills, a convection function, which are also “managed” by the control unit.

The control unit has its own power supply, which ensures the operation of the unit in both standby and operating modes. An important component is a relay unit that switches on commands the power circuits of the magnetron and the grill, as well as the circuits of the fan, the built-in lamp and the convector. The control unit is connected by loops to the keyboard and display panel.

An entertaining video with a story about the principle of operation of microwave ovens

See how simply explains what makes this amazing device work.