IntroductionThis article mainly introduces some commonly used electrical components in electrical control systems, which are good electrical introductory materials, and the electrical components in electrical control systems are devices used to control and manage the flow of electricity. In electrical control systems, there are many types of electrical components, each of which has different functions and functions. From circuit breakers, contactors, thermal relays to intermediate relays, buttons, and indicators, to sensors, power supplies, actuators, and computers, these components work together to ensure the proper functioning of electrical control systems. The circuit breaker is used to protect the circuit, the contactor controls the on/off of the circuit, the thermal relay protects the motor, the intermediate relay extends the contact, the button and indicator light are used for human-computer interaction, the sensor senses the physical quantity, the power supply provides the electrical energy, the actuator performs the control signal, and the computer performs the automatic management and control. The selection and matching of these components determine the performance and function of the control system.
Here we mainly introduce: circuit breakers, AC contactors, thermal relays, intermediate relays, button switches, indicator lights, transfer switches, and travel switches.
, circuit breaker
1.1 Circuit breaker**:
1.2 The role of the circuit breaker:
Low-voltage circuit breaker, also known as automatic air switch, not only has the function of manual switching, but also can automatically carry out loss of voltage, undervoltage overload and short circuit protection of electrical appliances.
It can be used to distribute electric energy, start asynchronous motors infrequently, protect power lines and motors, and automatically cut off circuits when they occur serious overload or short circuit and undervoltage failures.
1.3 Principle of circuit breaker:
1.4 Circuit breaker symbol and model:
Model: mainly DZ15, DZ20, DZ47 series.
AC contactors**.
2.2. Structure and working principle of AC contactor:
1) Basic Structure:
Electromagnetic mechanism: It is composed of a coil, a moving iron core (armature) and a static iron core.
Contact system: consists of primary and auxiliary contacts. The main contacts are used for:
The main circuit is switched on and off, and the auxiliary contacts are used in the control circuit.
Demonstration of the working process of the AC contactor.
2) Text symbol: km
3) Pictorial Symbols:
4) The main model of AC contactor is CJ**, and the specific model significance is as follows:
3. Thermal relay
3.1 Thermal Relay**:
3.2. Structure and working principle of thermal relay:
Thermal relays are based on the principle of thermal effects generated by the passage of electric current through components.
Relays for time-limited action.
1) Basic structure and working principle.
The working principle of thermal relays with phase failure protection:
2) Text symbol: fr
3) Pictorial Symbols:
4) Main models and technical parameters.
Commonly used thermal relays are: JR0, JR2, JR9, JR10, JR15, JR16,
JR20, JR36 and several other series.
3.3. Demonstration of the working process of the thermal relay:
4. Intermediate relay
4.1 Intermediate Relay**.
4.2. The structure and working principle of the intermediate relay.
The principle of an intermediate relay is a relay that converts one input signal into multiple output signals or amplifies the signal (i.e., increases the contact capacity). Its essence is a voltage relay, but it has a large number of contacts (up to 8 pairs), a large contact capacity (5 10A), and a sensitive action.
1) Text symbol: ka
2) Pictorial Symbols:
3) Uses. When the number of contact pairs of other appliances is insufficient, it can be expanded with the help of intermediate appliances.
The number of contacts they have. It is also possible to expand the energizing capacity of the contacts.
5. Button
5.1 button.
5.2. The structure and working principle of the button:
1) Basic structure and working principle.
2) Text symbol: sb
3) Pictorial Symbols:
4) Use of buttons:
1) The selection should be based on the number of contacts required, the place of use and the color.
Are you sure. Commonly used LA18, LA19, LA20 series push button switches, suitable for AC500V, DC440V, rated current 5A, control power for AC300W, DC70W control.
in the circuit. 2) Button color requirements:
The "Stop" and "E-Stop" buttons must be red. When the red button is pressed, the device must be stopped working or powered off.
The color of the "Start" button is green.
The button that alternates "Start" and "Stop" must be black, white, or gray, and must not be red or green.
The "Joe" button must be black.
The "Reset" (e.g. the reset button for a protective relay) must be blue. When the reset button still has a stopping effect, it must be red.
6. an indicator light
6.1 **:
6.2 The role of the indicator light:
The red and green indicator lights have three functions: one is to indicate the operation and stop of electrical equipment.
stop state; the second is to monitor whether the power supply of the control circuit is normal; The third is to use red lights.
Monitor whether the tripping circuit is normal, and use the green light to monitor whether the closing circuit is normal.
7. a transfer switch
7.1 Transfer Switch**.
7.2 The structure and working principle of the transfer switch.
1) Basic structure and working principle.
The universal transfer switch consists of an operating mechanism, a panel, a handle and several contact holders.
The main components are composed.
2) Text symbol: sa
3) Pictorial Symbols:
Each contact is passed when the handle is turned to a different gear.
Broken state with a black dot "ยท" indicated, there are black dots.
indicates that the contact is closed, and those without black dots indicate touch.
The head is disconnected. 8. a travel switch
8.1 Position switch**.
1) Basic structure and working principle.
2. Text symbol: sq
3) Pictorial Symbols:
Demonstration of the start and stop control mode of the motor contactor.