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Application of Micro Switch in Microwave Oven

The microwave oven, with its advantages of high efficiency, safety, time-saving, energy-saving, and simplicity, has been favored by people since its introduction. It has quickly entered thousands of households and become the top favorite of kitchen appliances among “white goods”.

What is the working principle of a microwave oven? And what does the micro switch do in microwave ovens?

I. How a microwave oven works

A microwave oven is a kind of cooking appliance that uses the microwave to heat food. It includes three main devices: magnetron — to generate microwave energy to heat food; waveguide — to transfer microwave energy to the food; cooking cavity — to contain the food and prevent microwave leakage.

how a microwave oven works


The working principle of the microwave oven is simple: the electrical energy is transformed into microwaves after the magnetron is powered on. When the microwaves are absorbed by the polar molecules in food (such as water, fat, protein, sugar, etc.), they will then vibrate at high frequencies and generate heat by friction. Therefore,  food will be heated from the inside out.

Consumers will have certain concerns about the leakage of microwave energy when they buy or use microwave ovens. Generally speaking, the requirements for oven doors are very high in the design of microwave ovens. The oven door is composed of a metal frame and a piece of the glass observation window. There is a layer of metal mesh in the glass interlayer of the observation window. What does it do? On the one hand, the process of heating food in the cooking cavity can be observed from the door outside; on the other hand, the microwave cannot leak out. Moreover, the size of the mesh hole in the glass interlayer is precisely calculated, so it can completely block the penetration of microwaves. If the oven door is opened, will there be a problem that all microwave energy is emitted? Well, the micro switch is a “safety guard” to solve this hidden danger. Here is an analysis of its composition and working principle.

II. The interlocking system of micro switch used in a microwave oven


interlocking system of a microwave oven

As shown in the figure, the consumer presses the door button, and its motion generates a displacement. This displacement triggers the counterclockwise rotation of the rotating board, which drives the clockwise of the rotary level and then ejects the upper and lower door hooks out of the limit structure of the interlocking support. The primary switch and the secondary switch are disconnected, and the monitor switch is closed. Finally, the oven door will be opened. At this point, the circuit is completely broken, and the microwave oven can not work. 

Microwave oven simple circuit diagram

(The Oven Door is Closed) 

Similarly, the consumer closes the oven door, which can touch the clockwise rotation of the rotating board to drive the counterclockwise rotation of the rotary lever. Then the door hook enters the locking hook holes, the primary micro switch and the secondary micro switch are on, and the monitor micro switch is off. Under this circumstance, the circuit can be connected before the microwave oven works.

What if the primary switch and the second switch fail? That is, when the oven door is in the normally open state, those two switches are closed  and the circuit works. Needless to say, the microwaves will radiate directly from the cooking cavity and cause danger at this time. Is there any solution to stop this from happening? Of course, that’s why a monitor micro switch is added to the circuit design. In case of the above special situation, the conduction of the monitor switch can form a short circuit in the front-end circuit. This protection action will cut off the power supply and make the microwave oven unable to start normally, to prevent microwave leakage. Therefore, the monitor switch is also called the safety switch.

According to the International Electro technical Commission (IEC), every microwave oven must have at least one interlocking system. It can be seen that the ingenious application of micro switches allows consumers to use microwave ovens without concern.

Zhejiang kangerle electronics co., Ltd has been specialized in manufacturing micro switches over 30 years. The quality of product is stable and reliable, trusted by customers for a long time.

KW3-6C-A 01


 KW3-6C-A and KW3-6A-A micro switches of KW3 series have been used in microwave ovens,  please visit our website for more product information.

Post time: May-25-2022

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