First, look at the general steps of the electrical diagram.
1. See the drawing for details.
After you get the drawings, you should first carefully read the main title bar and related instructions of the drawings, such as drawing catalogue, technical specification, list of electrical components, construction instructions, etc. Combined with the existing electrician knowledge, you should have a clear understanding of the types, properties and functions of electrical drawings, and understand the general situation of the drawings and the key points to be expressed as a whole.
2. Look at sketches and block diagrams
Because the schematic diagram and block diagram only roughly represent the basic composition, relationship and main characteristics of the system or subsystem, it is necessary to look at the circuit diagram in detail immediately to understand their working principles. Sketches and block diagrams are mostly single-line diagrams, and only some sketches of 380/220 V low-voltage distribution system are represented by multi-line diagrams.
3. Looking at the circuit diagram is the key and difficult point.
Circuit diagram is the core of electrical drawing, and it is also the most abundant and difficult part of electrical drawing.
To read the circuit diagram, we should first look at the graphic symbols and text symbols, understand the functions of each component of the circuit diagram, and distinguish between the main circuit and the auxiliary circuit, the AC circuit and the DC circuit. Secondly, look at the picture in the order of main circuit first and then auxiliary circuit.
Looking at the main circuit is generally from the bottom up, that is, starting from the electrical equipment, controlling the electrical components and looking at the power supply side in turn. When looking at the auxiliary circuit, look from top to bottom and from left to right, that is, look at the main power supply first, then look at each branch in turn, analyze the working situation of electrical components in each branch and their control relationship to the main circuit, and pay attention to the connection relationship between electrical and mechanical mechanisms.
Looking at the main circuit, it is necessary to find out how the load gets power, which electrical components the power cord has to pass through to reach the load, and why it has to pass through these electrical components. By looking at the auxiliary circuit, we can understand the composition of the auxiliary circuit, the interconnection and control relationship between electrical components and their actions. At the same time, it is necessary to understand the relationship between the auxiliary circuit and the main circuit, and then understand the working principle and context of the whole circuit.
4. Compare the circuit diagram with the wiring diagram.
Comparing the wiring diagram with the circuit diagram helps to see the wiring diagram clearly. When looking at the wiring diagram, it is necessary to check from the power supply side in turn according to the terminal mark and loop mark, to find out the line direction and circuit connection mode, and how each branch forms a closed loop through various electrical components.
The internal and external circuits of the switchboard (screen) must be connected with each other through the terminal board. Generally speaking, there are several rows on the switchboard and several rows of contacts on the terminal board. The number of lines of the external circuit can only be connected to the same number of contacts on the terminal board. Therefore, when looking at the wiring diagram, we must pay attention to the wiring situation of the terminal board in order to make the circuit inside and outside the switchboard (screen) clear.
Second, look at the method of electrical control circuit diagram
The general way to look at the electrical control circuit diagram is to look at the main circuit first, then at the auxiliary circuit, and use the loop of the auxiliary circuit to study the control program of the main circuit.
1. See the steps of the main circuit.
Step 1: See the electrical equipment in the main circuit clearly. Electrical equipment refers to electrical appliances or electrical equipment that consume electric energy. First of all, we should see clearly how many kinds of electrical appliances there are, their categories, uses, connection methods and some different requirements.
Step 2: Find out the electrical components that control the electrical equipment. There are many ways to control electrical equipment, some are directly controlled by switches, some are controlled by various starters, and some are controlled by contactors.
Step 3: Understand the control and protection appliances used in the main circuit. The former refers to other control elements besides conventional contactors, such as power switch (transfer switch and air switch) and cam switch. The latter refers to the specifications of short-circuit protection devices and overload protection devices, such as electromagnetic release and thermal overload release in air switches, and the uses and specifications of fuses, thermal relays and overcurrent relays. Generally speaking, after analyzing the main circuit as above, you can analyze the auxiliary circuit.
Step 4: Look at the power supply. Need to know the power supply voltage level, whether it is 380V or 220V, whether it is from bus, distribution panel or generator set.
2. Look at the steps of the auxiliary circuit.
The auxiliary circuit includes control circuit, signal circuit and lighting circuit.
Analysis control circuit. According to the control requirements of the motor and actuator in the main circuit, other control links in the control circuit are found one by one, and the control circuit is divided into several local control circuits for analysis according to different functions. If the control circuit is complex, we can exclude circuits that are not closely related to the control, such as lighting and display, so as to concentrate on the analysis.
Step 1: Look at the power supply. First, see clearly the type of power supply. Yes ... >>
Question 2: How to learn to understand the circuit schematic diagram? Just find a book on circuit principles. There are many theorems, examples and analytical methods. If you do all the exercises after class, it will be no problem. Mainly exercise analysis method. If you forget who wrote this book, just remember to call it "Circuit Principle", a dark blue book. It doesn't matter. Just order any book, but they will be fine. Just read a book several times. I don't understand. Just watch it seven or eight times. That's how I learned. After reading the book a hundred times, it can still be circulated for so many years. It must be right. After so many knocks, come on.
Question 3: How to understand the circuit system diagram, regardless of strong current, weak current, analog and digital, we must first understand the component symbols of each unit. The new and old national standards should be mastered by heart, and the working principle, characteristics and functions of each unit component should be mastered. Master the working principle and analysis method of various basic unit circuits. The Legend of Typical Circuits of Practical Electricians published by Water Resources and Hydropower Press contains detailed explanations of various basic unit legends of electricians. And some typical schematic analysis of the whole machine and power distribution, which is very beneficial to beginners and intermediate learners. An integrated circuit manual (with commonly used integrated circuit block diagram and pin function) can be bought in major bookstores. Beginners should not look at the circuit diagram of the whole machine first, but step by step. Because there are many unit circuits, some components in the unit circuits are scattered or far away from the unit, so it is difficult for beginners to read the drawings. Starting from the block diagram-unit circuit diagram, the equivalent circuit diagram-complete machine circuit diagram covers a wide range. It takes a long time to understand a complete circuit quickly, which is not clear here. Step by step learning is very important, and the theoretical basis of electricity is very important. As the saying goes, it is difficult to get quick success at first, and soon you will encounter bottlenecks. If you have a preliminary electrical foundation, it is recommended to study electrotechnics from Higher Education Press first, which is a difficult point in the circuit diagram. Let me briefly talk about the following knowledge of digital circuits. You can learn 1, binary and binary code, decimal code step by step. Include differential circuit, integral circuit, limiting circuit, multi-resonant oscillation circuit, monostable and bistable circuit, etc. ) 3. Logic gates (AND, OR, NAND, NOR gates) 4. Flip-flop circuit (RS flip-flop, JK flip-flop, D and T flip-flop are required) 5. Combinatorial logic circuit (basic arithmetic unit, comparator, parity judging circuit, coding, etc.). ) This is beyond the scope of electronic technology analysis. Although you don't need to be familiar with the software, it is also difficult to understand the process, purpose and result of software processing signals. After you have the basic knowledge of digital circuits, you must be familiar with the signals of digital circuits. Because it is a digital signal of various pulse trains, the waveforms of these data stream signals can't be as helpful to the understanding of the circuit as analog circuits, so you should be mentally prepared.
Question 4: How to read the schematic diagram of the circuit? You are mainly unfamiliar with the basic circuit. Remember several basic circuits, such as amplifier circuit (high amplifier, intermediate amplifier and power amplifier), rectifier circuit (half wave, full wave and bridge type), coupling circuit (inductor and capacitor), filter circuit (high frequency and low frequency), oscillator circuit (sawtooth wave, sine wave and pulse), energy storage circuit (memory short circuit) and feedback circuit (positive feedback circuit). If you consider doing this major in the future, you must be very familiar with these circuits. With this foundation, you can basically understand what you have in your hand in the future.
Question 5: What do you think of the electrical system diagram? For people in the industry, this is just an ordinary three boxes. The total power is 69KW, the demand factor is 0.85, and the power factor is 0.9. Calculate the cable 99A, then T-connect the A box AL5- 1, the power is 30KW, the current is 43.05A, the circuit breaker has three poles, and the rated current is 50A, followed by the distribution circuit, BM65/65438.
Question 6: How to read the schematic diagram of the circuit? Hello, I guess you have such an opportunity now, so you are in a hurry.
But it's not that easy. One is to have a certain professional foundation, and the other is to have some practice.
If you are an electrical graduate, you basically have the first one.
Article 2 Practice can do this:
1, you can find a knowledgeable person to take you to the factory to see the common electrical equipment and give you a general description.
2. You can go to the place where the electrician works to see the common electrical components, or you can go to the electrical market.
Go to the bookstore to see if there are any useful books.
4. Look at some simple drawings first and learn to practice.
5. With the increase of knowledge, you can search relevant knowledge on the Internet.
In this way, you will have a great improvement in a month.
Question 7: What do you think of the electrical drawings? 1. Find out the power lines of the control circuit: L, N(220V), L 1, L2(380V), others are 24V ~ 24V.
2. From the L or L 1 terminal of the control power supply, see which button each branch current passes through, which normally open and normally closed contacts of contactors and relays, which coil, and finally N or L2 to form a closed loop.
3. Understand that the coil of the same contactor or relay is drawn separately from the normally open and normally closed contacts. When the coil of contactor and relay in a branch is energized, its normally open and normally closed contacts will control the on-off of the coil in the branch (that is, turn on or off the branch).
4. Analyze the normally open and normally closed contacts of all the button contacts, contactors, intermediate relays and thermal relays in a branch as a whole to see whether the combination of on-off states of normally open and normally closed contacts can form a path and whether the coil can be energized when the button is pressed.
5. Analyze the other branches one by one to see whether the combination of the normally open and normally closed contacts in this branch can connect this branch and energize the coil at the same time.
6. By combining the on-off states of contactors and intermediate relay coils of all branches and finding out the motors or other equipment they control, we can determine which motors or equipment are running and which are not running at the same time.
According to the above methods, you can easily understand the electrical wiring diagram. Wish you success! ! !
Question 8: How to read the electrical system diagram? . . . . . . . . . . . .