The working principle of the key switch is easy to understand. To put it bluntly, it is like this: there is an electromagnet adsorption device inside. Turn the circuit on or off. In this way, the functions of remote control of the line are realized.
In fact, the key switch is a button, which is usually used to turn on and off the control circuit. The key switch is a low-voltage electrical appliance that issues commands in electric drag. It is widely used as a master electrical appliance. , used to manually issue control signals to control contactors, relays, electromagnetic starters, etc. Its characteristic is that it is installed in the machines and instruments that are in progress. Most of the time, it is in the position of the initial free state. It is only converted to the second state (position) under the action of external force when the external force is removed. , due to the action of the spring, the switch returns to the initial position.
When the button is not affected by external force (ie static state), the opening and closing state of the contact is divided into the start button (ie the normally open button), the stop button (ie the normally closed button) and the compound button (ie the normally open and normally closed contacts are combined as 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 released; the opposite is true when the button is stopped, the contacts are separated when the button cap is pressed, and the contacts are automatically closed and reset when released. The composite key is that when the key 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 key cap is released, the normally open and normally open contacts are closed first. After breaking and resetting, the normally open contact is closed and reset again.
In our lives, key switches are very common, such as round key buttons, square illuminated buttons, etc. These are all available for consumers to choose and use. But sometimes we are very troubled, how is the key switch installed?
1. When the buttons are installed on the panel, they should be neatly arranged and arranged reasonably. They can be arranged from top to bottom or from left to right according to the starting sequence:
2. The installation and fixation of the button should be firm, and the wiring should be reliable. Apply a red button to stop, green or black to start or power up, don't get me wrong.
3. Due to the small distance between the button contacts, short-circuit faults are likely to occur if there is oil pollution, so the contacts should be kept clean.
4. The button board and button box on which the button is installed must be metal, and try to connect them with the general grounding bus of the machine tool. For the hanging button, a special grounding wire must be provided, and a metal pipe shall not be used as the grounding wire.
5. When the button is used in high temperature occasions, it is easy to cause the plastic deformation and aging, which will lead to loosening, resulting in a short circuit between the wiring screws. An insulating plastic tube can be added to the wiring screws to prevent short circuits.
6. The button with the indicator light is heated by the bulb, and the plastic lampshade is easily deformed after long-term use. The voltage of the bulb should be reduced to prolong the service life.
7. The "stop" button must be red; the "emergency stop" button must be a red mushroom head; the "start" button must have a protective retaining ring, and the protective retaining ring should be higher than the button head to prevent accidents Touch to make the device malfunction.
