The Function and Kinds of Push Button Switches

The button switch refers to a switch that uses a button to push the transmission mechanism, presses or disconnects the moving contact and the static contact, and realizes the circuit switching. Push button switch is a kind of master electrical appliance with a simple structure and very wide application. In electrical automatic control circuits, it is used to manually send control signals to control contactors, relays, electromagnetic starters, etc.

Basic Introduction

Button switch, also known as the control button (button for short), is a low-voltage electrical appliance that can be manually and generally reset automatically. Buttons are usually used in circuits to issue start or stop instructions to control the on and off of electrical coil currents such as electromagnetic starters, contactors, and relays.

A button switch is an electrical appliance that is used to switch on and off small current circuits that are pressed to act, and released to reset. Generally used in control circuits with AC and DC voltages below 440V and currents less than 5A. Generally, the main circuit is not directly manipulated, and it can also be used in interconnecting circuits.

In actual use, in order to prevent misoperation, buttons are usually marked or painted in different colors to distinguish them. The colors are red, yellow, blue, white, black, green, etc. Generally, red means “stop” or “dangerous” operation; green means “start” or “on”. The emergency stop button must be a red mushroom button. The button must have a metal protective retaining ring, and the retaining ring should be higher than the button cap to prevent the accidental operation of the button. The material of the button board and button box where the button is installed must be metal and connected to the main ground bus of the machine.

Structure Principle

There are many types of button switches, which can be divided into common snap button type, mushroom head type, self-locking type, self-resetting type, rotary handle type, indicator type, illuminated symbol type and key type, etc., including single button, double Button, I button and different combinations. Generally, it adopts a water accumulation structure, which is composed of a button cap, a return spring, a static contact, a moving contact, and a shell. It is usually made into a composite type. There are a pair of normally closed contacts and normally open contacts. Some products can pass The series connection of multiple elements increases the number of contact pairs. There is also a self-holding button, which automatically maintains the closed position after being pressed, and can only be opened after power failure.

When the button is not pressed, the moving contact is connected to the static contact above, and this pair of contacts is called a normally closed contact. At this time, the moving contact is disconnected from the static contact below. This pair of contacts is called normally open contacts: press the button, the normally closed contact is disconnected, and the normally open contact is closed; release the button, The original working state is restored under the action of the return spring.

Types of Push Button Switch

(1) Protective button: a button with a protective shell that can prevent the internal button parts from being mechanically damaged or people touching the live part. Its code is H.

(2) Movable break button: In the normal state, the switch contact is a kind of button that is connected.

(3) Moving and closing button: Under normal conditions, the switch contact is a kind of button that is disconnected.

(4) Movable on/off button: Under normal conditions, the switch contacts have both on and off buttons.

(5) Illuminated button: The button is equipped with a signal light, which not only is used to issue operation commands + also serves as a signal indicator, and its code is D.

(6) Action click button: that is, the mouse click button.

(7) Explosion-proof button: A button that can be used in places containing explosive gas and dust without causing an explosion. Its code is B.

(8) Anticorrosive button: It can prevent the intrusion of chemical corrosive gas, its code is F.

(9) Waterproof button: a sealed shell to prevent rainwater from intruding, its code name is S.

(10) Emergency button: There is a big red mushroom button head protruding outside, which can be used as a button to cut off the power in an emergency, and its code is J or M.

(11) Open button: A button that can be used for embedded installation and fixed on the panel of a switchboard, control cabinet, or console, and its code is K.

(12) Interlocking button: A button with multiple contacts interlocking with each other, and its code is C.

(13) Knob button: the rotary operation contact with the handle. There are two positions on and off, generally, a panel-mounted button and its code is X.

(14) Key-type button: a button that can be operated by inserting and rotating the key to prevent misoperation or for special personnel to operate. Its code is Y.

(15) Self-holding button: A button with a self-holding electromagnetic mechanism inside the button, and its code name is z.

(16) Combined button: A button with multiple button combinations, its code name is E.

How to choose your push button switch

(1) According to the different use occasions and specific purposes: select the type of button according to the use occasion, such as open type, protective type, waterproof type, anti-corrosion type, etc.; select the appropriate form according to the use, such as handle rotary type, key Type, emergency type, illuminated type, etc. For example, the general button on the panel of the console cabinet can be opened first; if you need to display the working status, use the indicator type; in very important places, in order to prevent unrelated personnel from misoperation, the key type should be selected; when there is corrosive gas Use the anti-corrosion type.

(2) Select the color of buttons and indicator lights according to the requirements of working status, instructions and working conditions: green for “start” or “power on”, and red for “stop”. In addition, the voltage of the indicator light (bulb) is divided into 6.3V, 12V, 24V, etc.

(3) Determine the number of different buttons according to the needs of the control loop: such as a single button, double button, three-button, multi-button, etc. For example, when three kinds of controls of “forward”, “reverse” and “stop” are required, three buttons can be used and installed in the same button box; when only “start” and “stop” control are required, two buttons are used to assemble them Inside the same button box.

Use and maintenance

(1) Check the button frequently to remove the dirt on it. Due to the small contact distance of the button, after years of use or when the seal is not good, the inflow of dust or oil in various stages of emulsion will cause the insulation to decrease or even a short circuit accident. In this case, insulation and cleaning must be done, and corresponding sealing measures must be taken.

(2) When the button is used in a high-temperature environment, it is easy to deform and age the plastic, causing the button to loosen, causing a short circuit between the terminal screws. According to the situation, a fastening ring can be added to tighten it during installation, or an insulating plastic tube can be added to the connection screw to prevent loosening.

(3) For the button with indicator light, the bulb will be heated, and the plastic lamp cover will be deformed for a long time, which will make it difficult to replace the bulb. Therefore, it is not suitable to be used in places where the power-on time is long; if you want to use it, you can appropriately lower the bulb voltage to extend its life.

(4) If poor contact is found, the reason should be found out: if the contact surface is damaged, it can be repaired with a fine file; if the contact surface has dirt or soot, it is advisable to wipe it with a clean cotton cloth dipped in a solvent if it is a contact spring. If it fails, it should be replaced. If the contact is severely burned, the product should be replaced.

How to choose your push button switch

(1) According to the different use occasions and specific purposes: select the type of button according to the use occasion, such as open type, protective type, waterproof type, anti-corrosion type, etc.; select the appropriate form according to the use, such as handle rotary type, key Type, emergency type, illuminated type, etc. For example, the general button on the panel of the console cabinet can be opened first; if you need to display the working status, use the indicator type; in very important places, in order to prevent unrelated personnel from misoperation, the key type should be selected; when there is corrosive gas Use the anti-corrosion type.

(2) Select the color of buttons and indicator lights according to the requirements of working status, instructions and working conditions: green for “start” or “power on”, and red for “stop”. In addition, the voltage of the indicator light (bulb) is divided into 6.3V, 12V, 24V, etc.

(3) Determine the number of different buttons according to the needs of the control loop: such as a single button, double button, three-button, multi-button, etc. For example, when three kinds of controls of “forward”, “reverse” and “stop” are required, three buttons can be used and installed in the same button box; when only “start” and “stop” control are required, two buttons are used to assemble them Inside the same button box.

Use and maintenance

(1) Check the button frequently to remove the dirt on it. Due to the small contact distance of the button, after years of use or when the seal is not good, the inflow of dust or oil in various stages of emulsion will cause the insulation to decrease or even a short circuit accident. In this case, insulation and cleaning must be done, and corresponding sealing measures must be taken.

(2) When the button is used in a high-temperature environment, it is easy to deform and age the plastic, causing the button to loosen, causing a short circuit between the terminal screws. According to the situation, a fastening ring can be added to tighten it during installation, or an insulating plastic tube can be added to the connection screw to prevent loosening.

(3) For the button with indicator light, the bulb will be heated, and the plastic lamp cover will be deformed for a long time, which will make it difficult to replace the bulb. Therefore, it is not suitable to be used in places where the power-on time is long; if you want to use it, you can appropriately lower the bulb voltage to extend its life.

(4) If poor contact is found, the reason should be found out: if the contact surface is damaged, it can be repaired with a fine file; if the contact surface has dirt or soot, it is advisable to wipe it with a clean cotton cloth dipped in a solvent if it is a contact spring. If it fails, it should be replaced. If the contact is severely burned, the product should be replaced.