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Key points for reading electrical schematic diagrams: How to interpret electrical schematic diagrams. Electrical schematic diagrams are generally divided into main circuits, control circuits, and protection circuits. The current flowing through the main circuit is relatively large, mainly to power the main electrical devices such as compressors, fans, water pumps, and electric heaters ； The control circuit is primarily used to supply power to the controller and the electrical components surrounding it, such as AC contactors and overcurrent protectors ； The protection circuit is the loop through which various protections of the unit are fed back to the controller or through which protection is achieved via the control circuit. Steps for viewing the diagram: ⑴ First, look at the main circuit to see what electrical devices are present in it. ⑵Check what electrical components are used to control the electrical devices in the main circuit. ⑶Check how many types of protection components are present in the protection circuit, and to where the protection circuits of these components feed back signals. http://img.civilcn.com/d/file/dianqi/dqlw/2019-12-05/16f260617465e86419e33770e61daaa4.jpg Composition of electrical schematic diagrams: Electrical schematic diagrams are generally divided into two main parts – the main circuit and the auxiliary circuits. The current flowing in the main circuit is relatively large; it is used to supply power to major electrical devices such as motors. This circuit is usually represented by thick solid lines on the left or top side of the diagram, and it is controlled by the auxiliary circuits. The auxiliary circuit is primarily used to supply power to the control devices; it is the circuit that controls the operation of the main circuit, which is why it is also referred to as a control circuit or control loop. It is usually depicted with thin solid lines on the right side or bottom of the diagram. Yes, the household grounding standard should be <4Ω, and there is also a significant difference. Principles for reading electrical control circuit diagrams: break it down into smaller parts, follow the logical flow, focus on the main components first and then the secondary ones, combine the individual elements into a whole, ensure safety protection, and conduct a thorough inspection. Adopting the principle of breaking things down into smaller parts, taking a particular motor or electrical component (such as a contactor or relay coil) as the focus, one analyzes its connection and disconnection status starting from the power source, moving from top to bottom and from left to right. Analysis methods and steps ① Analyze the main circuit: Whether it is circuit design or circuit analysis, the process starts with the main circuit. The function of the main circuit is to ensure that the drive requirements of the machine tool are met. From the composition of the main circuit, it is possible to determine the type and operating mode of the motor or actuator, as well as the control requirements such as starting, steering, speed regulation, and braking, along with the protection requirements. ②Analysis of the control circuit: The various control requirements of the main circuit are fulfilled by the control circuit. By applying the principles of breaking down complex tasks into smaller parts and following a logical sequence, the control circuit is divided into several separate control circuits based on their functions. Starting from the power supply and control signals, logical judgments are used to determine the control sequence, thereby presenting the automatic operation process of the circuit in a clear and straightforward manner. ③Analysis of auxiliary circuits: Auxiliary circuits include functions such as displaying the operating status of actuating elements, showing power supply status, measuring parameters, providing lighting, and issuing fault alarms. This part of the circuit is relatively independent; it serves an auxiliary role without affecting the main functions. Many parts of the auxiliary circuit are controlled by components in the control circuit. ④Analyzing interlocks and protection mechanisms: Production machinery has high requirements in terms of safety and reliability. To meet these requirements, in addition to choosing appropriate drive and control solutions, a range of electrical protections and necessary electrical interlocks are also installed in the control circuits. In the analysis of electrical control schematics, electrical interlocking and electrical protection are important aspects that must not be overlooked. ⑤Overall inspection: After breaking the system down into smaller parts and analyzing the working principle of each individual circuit as well as the control relationships between these parts, it is still necessary to examine the entire control circuit as a whole to ensure that nothing has been overlooked. In particular, it is necessary to examine and understand the relationships between various control elements from an overall perspective, in order to properly comprehend the function of each electrical component in the schematic diagram. Typically, each electrical device has a different electrical control circuit, but any control circuit is composed of some unit circuits (i.e., basic components). Therefore, when examining the image, one can analyze each basic component step by step and then combine them for a comprehensive analysis. If the circuit is complex, you can start by looking at the simpler parts and then move on to the more complex ones.