Speaking of the button switch, it has been very popular in daily life, it can be seen almost everywhere, and it is closely related to our life, so since it is a thing that is so closely related to our life, how much do you know about it? I believe that if you don’t have an understanding of this aspect, ordinary people generally don’t know much about it or don’t know much about it, and it’s not detailed enough, then the next step will start with simple questions about what a button switch is, what its principle is, how its structure is, and what are its features. Classification, and model descriptions that I usually don't understand. To help you better understand what is a button switch.
First of all, let's introduce what is a button switch and what is the principle of the button switch:
The button switch is referred to as a button, usually used to turn on and off the control circuit. It is a low-voltage electrical appliance that issues instructions in electric drive. It is a widely used master electrical appliance. In the electrical automatic control circuit, it is used for manual control. Send control signals to control contactors, relays, electromagnetic starters, etc. Its characteristic is that it is installed in the machine and instrument in progress, most of the time it is in the position of the initial free state, and it is only switched to the second state (position) under the action of external force when required, when the external force is removed , due to the action of the spring, the switch returns to the initial position. The push button switch can complete basic control such as start, stop, forward and reverse, speed change and interlock. Typically each push button switch has two pairs of contacts. Each pair of contacts consists of a normally open contact and a normally closed contact. When the button is pressed, the two pairs of contacts act simultaneously, the normally closed contact opens and the normally open contact closes.
After we know what a button switch is or have a certain understanding of the button switch, let's introduce the structure of the button switch:
The structure of the button switch: it consists of a button cap, a return spring, a fixed contact, a movable contact, a shell and a pillar connecting rod. The opening and closing state of the contacts when the button is not subjected to external force (that is, static state) is divided into a start button (that is, a normally open button), a stop button (that is, a normally closed button) and a compound button (that is, a combination of normally open and normally closed contacts). integrated button). For the start button, the contacts are closed when the button cap is pressed, and the contacts are automatically disconnected and reset when the button is released; the stop button is the opposite, the contacts are separated when the button cap is pressed, and the contacts are automatically closed and reset when the button is released. The composite button is when the button cap is pressed, the bridge-type moving contact moves downward, so that the normally closed contact is disconnected first, and then the normally open contact is closed; when the button cap is released, the normally open and normally open contact is first closed. After the break is reset, the normally open contact is closed and reset.
Next, we will introduce in detail what are the classifications of button switches. Although we have come into contact with many button switches in our daily life, are they all similar to us and feel almost the same? In fact, although they look similar in appearance, their functions or categories may be quite different. Therefore, the following will introduce in detail which categories there are:
①Push button switches are classified according to the purpose and structure of the contacts :
1. Normally open contact (moving contact): It refers to the contact in which the fixed contact and the movable contact are separated in the original state (the electrical appliance is not subjected to external force or the coil is not energized).
2. Normally closed contact (moving contact): refers to the contact in the original state (the electrical appliance is not subjected to external force or the coil is not energized), and the fixed contact and the movable contact are in a closed state.
3. Normally open (moving close) button switch, when it is not pressed, the contact is disconnected, and when it is pressed, the contact is closed and connected; when it is released, the button switch is reset and disconnected under the action of the return spring. In the control circuit, the normally open button is often used to start the motor, also known as the start button.
4. The normally closed (moving off) button switch is opposite to the normally open button switch. When it is not pressed, the contact is closed, and when it is pressed, the contact is disconnected; when the hand is released, the button switch is under the action of the return spring Reset closed. The normally closed button is often used to control the motor to stop, also known as the self-reset button.
5. Composite button switch: A button switch that combines a normally open and normally closed button switch, that is, has a normally closed contact and a normally open contact. When not pressed, the normally closed contacts are closed and the normally open contacts are open. When the button is pressed, the normally closed contact is disconnected first, and then the normally open contact is closed, which can be regarded as a self-locking button; when the button is released, the button switch first disconnects the normally open contact under the action of the return spring , and then close the normally closed contact. Composite buttons are used in interlock control circuits.
② Push button switches can be classified according to operation mode and protection mode:
1. Waterproof type: with a sealed shell to prevent rainwater from intruding.
2. Anti-corrosion type: it can prevent the intrusion of chemical corrosive gases.
3. Explosion-proof type: it can be used in places containing explosive gas and dust without causing explosion transmission, such as coal mines and other places.
4. Knob type: The contact is operated by rotating the handle, with two positions of on-off, generally panel-mounted.
5. Key type: use a key to insert and rotate to operate, which can prevent misoperation or be operated by a special person.
6. Open type: suitable for embedded and fixed on the panel of switch board, control cabinet or console.
7. Protective type: with a protective shell, which can prevent the internal button parts from being mechanically damaged or people touching the live parts.
8. Emergency type: There is a big red mushroom button protruding outside, which is used to cut off the power supply in case of emergency.
9. Self-holding button: The button is equipped with a self-holding electromagnetic mechanism, which is mainly used in power plants, substations or test equipment. Operators communicate with each other and issue instructions, etc., and are generally panel-operated.
10. Illuminated button: There is a signal light inside the button. In addition to issuing operation commands, it also serves as a signal indicator. It is mostly used on the panels of control cabinets and consoles.
11. Combined type: multiple button combinations.
12. Interlocking type: Multiple contacts interlock with each other.