Diagram of the electrical control circuit diagram - Database & Sql Blog Articles

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The electrical control circuit diagram can fully express the purpose, function and working principle of the electrical equipment, and is the theoretical basis for the installation, commissioning and maintenance of the electrical circuit. In the production practice, the installation electrician and the maintenance electrician must be exposed to various circuit diagrams. Some of these circuit diagrams are relatively simple and some are complicated. The author has accumulated some experience in mapping in many years of teaching practice.

Knowing the machine first, then knowing the electric machine first, you should first understand the basic structure, operation, process requirements and operation methods of the production machinery, in order to have an overall understanding of the structure of the production machinery and its operation. After the identification of electricity, it is based on the recognition of the machine and then clear the control requirements for electric drive, to prepare for the analysis of the circuit. For example, when explaining to students the circuit diagram of the domestic CA6140 ordinary horizontal lathe, the author first organized the students to visit the factory or the internship workshop to visit various types of ordinary horizontal lathes, so that students can understand that the lathe is from the bed, the headstock, Feed box, slide box, tool holder, lead screw, light bar, tailstock and other parts. After understanding the structure of the lathe, let the students know the movement form of the lathe, so that the student can confirm that the rotary motion of the workpiece is the main motion, and the linear motion of the turning tool is the feed motion. The motorized feed motion is also transmitted from the spindle motor to the feed box through the spindle box, and then the motion is transmitted to the slide box through the light bar or the lead screw. The slide box drives the tool holder to make the feed motion in both directions. At this time, the teacher can move the carriage to the far right of the bed by hand and ask the question: Is the operation efficiency too low? After the student answers, the teacher informs the student again: in order to improve labor productivity and reduce the auxiliary time, the setting is set. Tool holder fast motor. The teacher can demonstrate to the student that the rapid movement of the tool holder is controlled by a fast motor jog, and the direction of the tool holder movement is controlled by the operating handle. In this way, students can be curious and stimulate their desire for knowledge. During turning, due to the high temperature of the tool and the workpiece, cooling is sometimes required, so a cooling pump motor should be provided. Teachers should guide some students to practice lathes after fully demonstrating the lathe handling process. After the students understand the basic structure and operation of the CA6140 lathe, the control requirements for electric drive are clear. Teachers can first ask students to answer the characteristics of power drag and control requirements, and then give an answer. When explaining the various machine tool circuit diagrams such as Z37 type radial drilling machine, M1432A universal cylindrical grinding machine and X62W universal milling machine, we should organize students to visit the factory and the workshop to understand the structure of various machine tools and let the students know. The form of motion of various machine tools. Students can also perform simple manipulation exercises when necessary. In this way, students can clarify the control requirements for various machine tool electric drag. Then, the teacher explains how the various machine tools work in the classroom. This kind of teaching mode can make students clear the idea of ​​drawing, and it is easy to read the electrical control circuit diagram, thus improving the ability to map.

Knowing the Lord first, then knowing the Lord and knowing the Lord, is to start to understand the picture from the main circuit. First of all, it is necessary to see the equipment is driven by several motors, the role of each motor, combined with the processing technology to analyze the starting method of the motor, with or without positive and negative control, which braking method is used. Second, it is necessary to figure out what electrical components are controlled by the electrical equipment. Some are controlled by a knife switch, and some are controlled by a contactor or relay. Again, understand the role of other components in the main circuit, usually in addition to the contactors and relays used in electrical and control, as well as power switches, fuses and protective appliances. Finally, look at the power supply. Look at the main circuit power supply is 380V, or 220V. The main circuit power is supplied by the busbar bus or the power distribution panel. After the auxiliary, it is necessary to start from the main circuit when reading the auxiliary circuit, and analyze the control contents according to the control requirements of each electric motor and solenoid valve. Control content includes start, direction control, speed control and brake control. The auxiliary circuits in the circuit diagrams are also different due to the different types of production machinery. The auxiliary circuit includes a control circuit, a signal circuit, and a lighting circuit. For example, when I explained the circuit diagram of the domestic X62W universal milling machine to the students, I also organized the students to go to the factory or the workshop to understand the structural composition and movement form of the milling machine, so that the students can clearly define the electric drive control requirements. After returning to the classroom, explain to students how the circuit works. Teachers should have the ability to draw on the blackboard. For example, according to the control requirements of the milling machine, the student is guided to read the main circuit. There are three motors in the main circuit: (1) M1 is the spindle motor, the spindle is driven to drive the milling cutter for milling, the KM1 contactor controls the start and stop, and the reverse switch SA3 acts as the M1 commutation switch. The author guides the students to analyze and draws the main circuit that controls the spindle motor on the blackboard. (2) M2 is a feed motor. The feed motor is used to drag the feed motion and rapid movement in the front, back, left and right, and up and down directions of the table. The forward and reverse rotation is controlled by the contactors KM3 and KM4. At the same time, the main circuit of the control feed circuit is drawn on the blackboard. (3) M3 is a cooling pump motor for supplying coolant. When M1 is started, M3 can be started. It is controlled by manual switch SQ2, and the main circuit for controlling the cooling pump motor is drawn. The three motors share the fuse FU1 for short-circuit protection, and the three motors are protected by FR1, FR2 and FR3 for overload protection. The teacher guides the students to understand the picture while explaining and drawing, so that the students can easily accept and understand. After reading the main circuit, the student is guided to read the control circuit. When reading the control circuit, start from the main circuit. Because the spindle motor M1 adopts the two-ground control mode, the start buttons of the two places are connected together, and the stop buttons of the two places are connected in series. The author draws the control loop of the spindle motor from the secondary side of the control transformer. The control loop of the feed motor is drawn in turn while explaining, and finally the illumination circuit and the signal display circuit are drawn. The author uses this teaching method to explain to students the various machine tool circuits, so that students can understand the circuit diagram.

It is zero, and any complex circuit that reads each local circuit is composed of some basic links. Therefore, mastering the working principle of the basic link circuit is the basis for mastering the electrical operation, installation and maintenance of the machine tool. The analysis control circuit can find out the control links in the control circuit one by one according to the control requirements of each motor and the execution appliance in the main circuit, and analyze the control loop to zero. If the control circuit is more complicated, the circuit that is not closely related to the control such as illumination or display can be excluded to concentrate on the analysis. The process of analyzing the control circuit is: First, see if the control power supply is AC or DC, where it is connected and its voltage level. The control power supply is generally connected from the two phase lines of the main circuit, and its voltage is 380V. It is also connected from one phase line and zero line of the main circuit, and its voltage is 220V; in addition, it is also connected from a dedicated isolated power transformer. Commonly used voltages are 110V, 36V, 24V, 12V and 6V. Second, see how the auxiliary circuit controls the main circuit. In a complex auxiliary circuit diagram, the entire auxiliary circuit forms a large loop. In the large loop, it is divided into several independent small loops, each of which controls an electrical appliance or an action. When a small loop forms a closed loop and a current flows, the contactor or relay in the loop acts to connect the motor to the power source or cut off the power. Again, study other electrical equipment and electrical components, such as rectifier equipment, lighting, etc., to understand their route and role. For example, when the author explained to the students how to read the M1432A universal cylindrical grinder circuit, firstly, the students were instructed to analyze the control loop power supply, so that the students knew that the control power was reduced by the control transformer TC to 380V AC voltage to 110V, 24V and 6V, 110V voltage. Supply control loop, 24V supply lighting circuit, 6V as power supply for signal circuit. Secondly, according to the control requirements of the M1432A universal cylindrical grinding machine, the students are guided to analyze how the control loop controls the main circuit. Because there are five motors in the main circuit, there are five separate small circuits in the entire control loop. If the entire control loop is divided into five local control circuits to analyze the reading, then the map is simplified. The teacher first instructs the student to analyze how each contactor or relay connects the motor to or from the power source when each small loop forms a closed loop. Teachers should explain each local control circuit to the students. Finally, the students are instructed to read the grinder lights and indicator circuits that are not closely related to the control circuit.

Set the zero as the whole, and check the overall situation. After summarizing the characteristics and normalizing the working principle of each local circuit and the control relationship between the parts, the whole control circuit must be checked by the method of “collecting zeros as a whole”. See if there are any omissions. In particular, the relationship between the various control links should be further examined and understood from a holistic perspective to understand the role of each electrical component in the circuit. In the process of image recognition, you should also observe all the circuits, observe the relationship between the local circuits, and what protection links are provided in the circuit to have a clear understanding of the entire circuit. The role of each of the circuits in the circuit, each contact in the electrical appliance should be clearly understood, in preparation for summarizing the features. All electrical components in the circuit are not isolated, but are interconnected and mutually constrained. In the circuit, the electrical component A is controlled by the electrical component A, and even the electrical component B is used to control the electrical component C. This mutually restrictive relationship sometimes manifests itself in the same loop, sometimes in several different loops. For example, when instructing students to analyze the CA6140 lathe circuit, when the contactor KM1 of the control spindle motor is energized and pulled, the KM1 auxiliary contact is closed, and then the contactor KM2 of the cooling pump motor can be powered to realize electrical The component KM1 controls the electrical component KM2. For example, when analyzing the X62W universal milling machine circuit, when the contactor KM1 of the control spindle motor is electrically connected, the KM1 normally open contact is closed, and the contactors KM3 and KM4 of the control table feed motor can obtain power. The above two examples are typical of sequential interlock control. There is also the X62W universal milling machine. The feed motor needs positive and negative rotation control. Therefore, the normally closed contacts of the two contactors KM3 and KM4 controlling the feed motor are mutually constrained by the mutual coil circuit, ensuring that the two contactors cannot operate at the same time. M1432A universal cylindrical grinding machine, two contactors for controlling the high and low speed of the headstock motor and two contactors for controlling the inner and outer grinding wheel motors need to be mutually restricted to ensure that the two contactors cannot work at the same time. This mutually restrictive control relationship is electrical interlocking, also known as electrical blocking. After collecting the zeros as a whole and observing the overall situation, after reading the electrical control circuit diagrams of various machine tools, the students should summarize the existence of sequential interlock control and electrical interlock control in the circuit.

The above-mentioned diagram of the electrical control circuit diagram is the teaching method that the author often uses in many years of teaching. In the teaching, it should be used flexibly according to the actual situation to mobilize the students' enthusiasm for learning, highlight the students' subject status, and cultivate students' ability to analyze and solve problems and the ability to map and draw.