The button switch may be the simplest component in the electrical circuit, but it controls the lifeblood of the entire control circuit, so it is also called the "master switch". Understanding all kinds of button switches and using them skillfully and flexibly can make us get twice the result with half the effort.
Button switches are used to switch on or off small current circuits in a short period of time, and are mainly used in electrical control circuits. The current allowed to flow through the button switch is small, generally not more than 5A.
The button is generally composed of a button cap, a return spring, a bridge-type moving contact, a static contact, a pillar connecting rod, and a housing. The opening and closing state of the contacts when the button is not subjected to external force (that is, static), is divided into a stop button (that is, a dynamic break button), a start button (that is, a dynamic close button) and a reset button (that is, a combination of a dynamic close and a dynamic break. integrated button). When the button is under the action of external force, the opening and closing state of the contact changes: the normally open contact under static state is closed, and the normally closed contact under static state is open.
Push button switch, also known as control button (referred to as button), is a low-voltage electrical appliance that can be manually reset and generally automatically reset. Buttons are usually used in circuits to issue start or stop commands to control the on and off of electric coil currents such as electromagnetic starters, contactors, and relays.
The push button switch is an electrical appliance that is used to turn on and off small current circuits, which is pressed to act and released to reset. It is generally used in control circuits with AC and DC voltages below 440V and currents less than 5A. Generally, it does not directly control the main circuit, but can also be used in interconnected circuits.
In actual use, in order to prevent misoperation, the buttons are usually marked with different marks or painted with different colors to distinguish them. The colors are red, yellow, blue, white, black, green, etc. Generally, red indicates operation in a "stop" or "dangerous" situation; green indicates "start" or "connect". The emergency stop button must use a red mushroom head button. The button must have a metal protective retaining ring, and the retaining ring should be higher than the button cap to prevent accidental touch of the button and cause malfunction. The material of the button plate and button box where the button is installed must be metal and connected to the general ground bus bar of the machine.
Use Maintenance Edit
(1) The button should be checked frequently to remove the dirt on it. Due to the small distance between the contacts of the button, after many years of use or when the seal is not good, dust or various stages of oil emulsion will flow in, which will cause insulation reduction or even a short circuit accident. In this case, insulation and cleaning must be carried out, and corresponding sealing measures must be taken.
(2) When the button is used in a high-temperature place, it is easy to deform and age the plastic, causing the button to loosen and causing a short circuit between the wiring screws. According to the situation, a fastening ring can be added to tighten it during installation, and an insulating plastic tube can also be added to the wiring screw to prevent loosening.
(3) The button with the indicator light is easy to deform the plastic lampshade due to the heat of the bulb for a long time, which makes 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 properly reduce the voltage of the bulb to prolong its service life.
If poor contact is found, the cause should be found out: if the contact surface is damaged, it can be repaired with a fine file; if there is dirt or soot on the contact surface, it should be wiped clean with a clean cotton cloth dipped in solvent; if the contact spring If it fails, it should be replaced; if the contact is severely burned, the product should be replaced.
Metal button switch (push-buttons switch) refers to a switch that uses a button to push the transmission mechanism to make the moving contact and the static contact press on or off and realize the circuit switching. The metal push button switch is a master electrical appliance with a simple structure and a wide range of applications. In electrical automatic control circuits, it is used to manually send control signals to control contactors, relays, electromagnetic starters, etc.
With the rapid development of microelectronics technology, the control technology is becoming more and more perfect and mature. As the core component of industrial control, the metal button switch has more and more powerful control functions, smaller and smaller volume, and more high-speed and reliable operation. ; The human-machine interface (HMI) has completely broken the traditional operation modes such as buttons and signal lights, making the equipment operation interface more popular, friendly, flexible and diverse, and its powerful storage function and communication capability have brought difficulties to equipment manufacturers and users. It is the general trend to replace the traditional equipment operation interface with the desired benefits and convenience; the control technology of the frequency converter used for ordinary motor speed regulation has far exceeded the early single metal button switch control method, and is rapidly moving towards sensorless The development of vectorization and direct torque control has made it widely used in various industries.
Classified according to the purpose and structure of the contact
(1) Normally open button
(2) Normally closed button
(3) Compound button classified according to operation mode and protection mode Buttons can be classified according to operation mode and protection mode, common button categories and characteristics:
(1) Open type: suitable for embedded and fixed on the panel of switch board, control cabinet or console.
(2) Protective type: with a protective shell, which can prevent the internal button parts from being mechanically damaged or people touching the live parts.
(3) Waterproof type: with a sealed shell, which can prevent rainwater from intruding.
(4) Anti-corrosion type: it can prevent the intrusion of chemical corrosive gases.
(5) 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.
(6) Illuminated button: There is a signal light inside the button, which is not only used to issue operation commands, but also serves as a signal indicator, and is mostly used on the panels of control cabinets and consoles.
(7) Key type: Insert and rotate with a key to operate, which can prevent be operated by a special person.
(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) Knob type: The contact is operated by rotating the handle, with two positions of on-off, generally panel-mounted.
(11) Combined type: combination of multiple buttons. (12) Interlocking type: Multiple contacts interlock with each other. Code-named off, on.
The main technical parameters
Switch rating: ac-15 36v/10a 110v/10a 220v/5a 380v/2.7a 660v/1.8a dc-13 24v/4a 48v/4a 110v/2a 220v/1a 440v/0.6a
Conventional thermal current: 1th 10a
Electric shock Resistance: ≤50mΩ
Insulation resistance: ≥10mΩ
Mechanical life: general button n≥100×10 times; knob ≥30×10 times.
Key button n≥5×10 times; emergency stop button ≥5×10 times
