1. Air switch
Air switch, also known as air circuit breaker, referred to as air open, is an indispensable element of the control cabinet, usually from the outside into the cabinet power supply, must go through the air open, in order to reach the inside, the function of air open in addition to the power supply, more as short circuit protection and overload protection. When a short circuit or overload is detected in the internal power supply, the power supply can be cut off instantaneously to prevent more serious accidents.
Generally speaking, the leakage protector is similar to the nature of the air open, and it also plays the function of short circuit and overload protection, but it is rarely used in industry, the main reason is that the leakage protection is too sensitive, and the slightest current imbalance will cut off the main power supply, which is not applicable in industrial control, and it is more to use the leakage protection for household use to protect people from electric shock.
2. Switching power supply
The switching power supply can convert the AC 220V power supply into a direct 24V power supply, which is commonly known as weak current, which is used to control solenoid valves, AC contactors, intermediate relays, or to supply power to PLC and touch screen.
The switching power supply is not essential in the electrical cabinet, usually the DC power supply we use in the industry is DC24V.
3. Intermediate relays
The role of the intermediate relay can be seen from the name, as an intermediary to use, usually the current output of the PLC is relatively small, if it is directly used to control the external equipment of the large current, it may burn the output point of the PLC, in order to protect the PLC, we add an intermediary in the middle of the circuit, use the weak current to control the strong current, or use the small current to control the large current, or to achieve remote control.
The input of the intermediate relay is generally DC24V, and the contacts are divided into two or four groups, each group is a pair of normally open points and a pair of normally closed points, which can be selected according to needs.
Generally, intermediate relays are electromagnetic, and they are inducted through a mechanical structure. There is also a type called solid-state relay, which has no physical contact, can be switched on and off without contact, and can be used for high-frequency control applications.
Thermal relays are the most widely used in temperature control.
4. AC contactor
The function of AC contactor is similar to that of intermediate relays, which is also used to control large currents with small currents, and to control multiple strong currents with one power seeking, and is usually used in the control circuit of three-phase or single-phase motors.
The AC contactor has three main touches, the auxiliary contacts can have a group of normally open or a group of normally closed, which is used to feedback the signal to the PLC, and some models can have two sets of auxiliary contacts, one group of normally open and normally closed.
Usually, the AC contactor should also be connected in series with a thermal relay, referred to as thermal protection, to prevent the current generated by the overload of the circuit circuit and protect the motor.
5. Terminals
There are many styles of terminal blocks, and the main function is the transfer between circuits, which you can choose according to your needs
6. Cable slot
The wiring duct is placed in the control cabinet, and all the wires pass through the wiring duct, making the wiring more beautiful and orderly.
When selecting the wiring duct, it is necessary to fully consider the cross-sectional area of the wire, and choose the appropriate size of the trunking to prevent the cable from being overcrowded, resulting in overheating, fire and other accidents, and generally reserve 30% of the space for heat dissipation.
7. Guide rails
The rails are fixed to the mounting plate for quick installation of other components. At present, most of the components have achieved the standard installation system
It can be installed directly.
8. Other Annexes
Other accessories are not commonly used, but sometimes they are used, such as fuse holders, power filters, etc., and you are qualified to choose your components to be a qualified electrical engineer.
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