How the microwave works

Content:

The principle of operation of the microwave oven
How are these waves created?
The purpose of the thermal fuse
Purpose of the cooler in the microwave
How is microwave protection provided
Device control unit
Output

Microwave ovens or so-called microwave ovens have become devices that are located in the kitchen of almost everyone. With their help, you can easily reheat already cooked food, or defrost them. Some craftsmen have learned how to cook a huge number of dishes in a microwave oven or disinfect a sponge or cloth. If you are interested in the principle of operation and the device of a microwave oven, then we will try to answer it in this article.

To make it convenient for the user to operate the device, an intuitive interface was included in its design, which is equipped with a child protection system and programs for quick cooking. In case of any malfunctions, you can, in most cases, fix them yourself.

The principle of operation of the microwave oven

In order to reheat food, you need to put the dishes with food in the microwave and select the program, in the case of using fast heating, you need to set the time. Products are heated by exposure to powerful electromagnetic radiation. The frequency of the microwave oven, which is installed in the kitchen, is 2450 MHz. How food is heated: High-frequency waves penetrate deep into the food and begin to affect polar molecules (most often water), causing them to cycle along the lines of force of electromagnetic fields.

Thanks to this method, food is heated not only outside, but also inside the food. In most models used in the kitchen, this figure is from 2.5 to 3 centimeters.

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How are these waves created?

To generate radio waves of a given frequency, a special device called a magnetron is used, which is an electrovacuum diode consisting of a large cylindrical anode made of copper, which combines 10 wall sectors, and they are also made of copper.

In the center of the device is a rod cathode, with a filament inside the channel. The cathode is designed for the emission of electrodes. In order for the unit to generate microwave radiation, you need to create a magnetic field in the cavity of the magnetron. For this, powerful ring magnets are used, which are located at the ends of the part.

To create an emission, it is necessary to apply a voltage of four thousand volts to the anode, and only three to the channel filament.

To remove energy, the structure of the device includes wire loops that are connected to the cathode, and that in turn is output to the so-called "radiating antenna". From this device, the generated radiation goes directly to the waveguide, which distributes it throughout the main chamber. Often the standard power of this element, which is installed in most models of microwave ovens, is about 810 watts.

If less power is needed for heating or cooking, then the magnetron simply turns on and off cyclically.

In science, this phenomenon is called pulse width modulation. In order for the device to produce 400 W, namely half of its output power within a 20-second interval, it is necessary to de-energize the magnetron for 10 seconds, and then supply electricity for the same 10 seconds.

The device generates a large amount of heat during operation, therefore, to cool it, the element is installed in a plate radiator, so that it is constantly blown by air currents, thanks to a small cooler built into the microwave. In case of overheating, this structural element can simply fail, therefore it is equipped with a protective device, namely a thermal fuse.

The purpose of the thermal fuse

In order to protect the magnetron and grill, which is installed in some microwave ovens, from overheating, the design provides for the installation of a thermal relay, or as they are also called thermal fuses. They are divided by their ability to withstand different amounts of heat, in order to find out which one you need, you need to find a sticker with information on the device’s body or look in the technical passport of the device.

In fact, the device is quite simple in principle of understanding its operation. The body of the product is made of aluminum alloy. The device is mounted using a flange connection, which is able to provide a snug fit with the area where temperature measurements will be directly performed. Inside the case is a bimetallic plate, which is made with the expectation of resistance to certain temperatures.

In case of exceeding a predetermined threshold, the plate is simply compressed and thereby actuates the pusher, which is designed to open the contact group. The power supply is interrupted and the furnace ceases to function. Cooling gradually, the plate returns to its original shape and closes the contacts again.

The purpose of the cooler in the microwave

A cooler is one of the most important components of a microwave oven, without it there will be a full-fledged functioning of the device. Thanks to him, the following functional tasks are carried out:

Magnetron cooling, to ensure its proper operation.
Cooling other system components that can also generate heat, such as electronic circuits.
Some microwave ovens are equipped with a grill function and a cooler is installed to cool the thermal relay.
To create excess pressure in the cavity where the food is placed. Due to this, air and vapors are removed, which are removed through specialized ventilation ducts.

In microwave ovens, cooling is carried out with the help of a single fan, which distributes the air through the chamber with the help of special air vents that direct air to the spare parts for their cooling.

How microwave protection is provided

Since the magnetron emits strong electromagnetic radiation, which can harm the human body and pets, the device uses a multi-level protection system.

The working chamber of the device is covered with enamel to block radiation, and from above it is closed with a metal casing, which completely prevents its exit to the outside.

To protect the glass window, in the door of the device, use a mesh with small cells, which is made of steel, and it blocks radiation up to 2450 Hz, with waves up to 12 cm long.

The door must fit well to the body and have no gaps. In the case when the clearance between them increases, it is necessary to check the loop and return it to its original state.

Between them, constant electromagnetic waves can be formed, which are located directly in the place of contact of the door and the device case, and has a zero amplitude value, which is why the emitted waves cannot propagate outside the case. This method was called in science as "microwave choke".

The device is protected from being switched on with an open camera by a system of microswitches that control and fix the position of the door in it. Most often, the device provides from three such switches:

Turning off magnetron.
Controlling the backlight bulb.
The switch controls the position of the door and informs the control unit about its position.

Device control unit

The command device is installed in each device currently manufactured, it provides two functions:

Maintaining a given device power.
Turning off the device after performing the specified operation.

In older models, the device is made of two electromechanical switches, which were responsible for the above functions. Over time, technology has evolved and blocks have been invented with electrical controls. At the moment, microprocessors are installed in the devices, which can be equipped with additional programs to simplify use, some functions: automatic defrosting of foods and preparation of certain dishes, built-in clocks, indicators showing power, sound signals about the completion of the process.

The command control panel is equipped with a personal power supply, which powers it autonomously while the microwave oven is operating.

Output

In this article, we examined the principle of operation and the device of the microwave oven, got acquainted with its internal components and the possible use of the device in the home space. Undoubtedly, she can make life easier for anyone in the kitchen and save a lot of time.