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How to read an electrical wiring diagram? Makes it easy to read and understand wiring diagrams!

READING A WIRING DIAGRAM IS THE MOST BASIC SKILL TO BECOME A QUALIFIED ELECTRICIAN.

What is a circuit diagram? Circuit diagrams use wires to connect the power supply, switches (keys), electrical appliances, ammeter, voltmeter, etc. to form a circuit, and then in accordance with the unified symbols to represent them, so that the drawing is called a circuit diagram. A circuit diagram is a graphical representation of a physical drawing using symbols.

Circuit diagram is people for research, engineering planning needs, with physical and electrical standardized symbols drawn a representation of the composition of the components and the relationship between the devices of the principle of the layout of the diagram. Circuit diagrams allow you to understand how components work together, and provide planning solutions for analyzing performance and installing electronic and electrical products. It may be more troublesome to design circuit diagrams, but it is easy to learn to read them.

In fact, the knowledge of circuit diagrams is not too difficult, a little study, you can easily read circuit diagrams.

As an electrician, we may encounter a lot of unfamiliar circuits, this time a circuit diagram becomes very important.

First of all, you need to know the meaning of the drawing of each component of the circuit diagram, and the actual item corresponds to. Secondly, you need to understand the method of drawing between the lines, again is to see more, do more, understand the direction of the electrician line, the specification.

Electrical drawings can be generally divided into two categories, one type of electrical diagrams for the power, it is

 mainly expressed in the transmission, distribution and conversion of electrical energy, such as electrical diagrams of the power grid, electrical control diagrams of power plants and so on. Another category of electrical diagrams for electronic, it is mainly expressed in the transmission of electronic information, processing; such as television electrical schematic diagrams. In this paper, we mainly talk about the reading of electric power diagrams.

Power electrical diagrams are divided into primary circuit diagrams, secondary circuit diagrams. Primary circuit diagram indicates the primary electrical equipment (main equipment) connection sequence. Primary electrical equipment mainly includes generators, transformers, circuit breakers, motors, reactors, power cables, power buses, transmission lines and so on.

For the primary equipment and its circuit control, measurement, protection and design and installation of various types of electrical equipment, such as measuring instruments, control switches, relays, signaling devices, automatic devices, etc. called secondary equipment. The electrical diagram indicating the connection sequence between the secondary equipment is called the secondary circuit diagram.

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 1.Types of electrical diagrams

  Electrical diagrams mainly include system schematic diagrams, circuit schematic diagrams, installation wiring diagrams

① System schematic (block diagram)

With simple symbols or boxes with text, simple and clear representation of the most basic structure and composition of the circuit system, visual representation of the most basic components of the circuit unit and the main features and interrelationships.

② Circuit schematic

Circuit schematic diagrams are divided into two types: centralized and expanded. Centralized circuit diagrams of the components are drawn in the form of a whole centralized, explaining the structural principles of the components and the principle of operation. Readers need to clearly understand the diagram of the relay coil, contacts belong to what circuit, under what circumstances action, after the action of the relevant part of the contact what kind of change.

Expanded circuit diagrams in the components, relays show the principle of action, the sequence of action, compared with the centralized circuit diagrams have their unique advantages.

Expanded circuit diagrams according to the coil of the component, contacts are divided into their own independent AC current, AC voltage, DC signals and other circuits. All belong to the same component or relay current, voltage coil and contacts using the same text.

Expanded circuit diagram for each independent circuit, AC according to U, V, W phase sequence; DC according to the sequence of relay action sequential arrangement. When reading the unfolded circuit diagram, read the text description on the right side of each circuit, first AC and then DC, from top to bottom, from left to right, line by line. Centralized, expanded circuit diagrams complement each other, read against each other easier to understand.

③Installation Wiring Diagram

Installation and wiring diagrams are drawn on the basis of the circuit principle, which is an important and indispensable information for on-site maintenance. Installation diagram of the components of the graphics, location and connection between each other and the actual shape of the components, the actual installation location and the actual connection relationship is consistent. The connection relationship in the diagram is expressed by the relative labeling method.

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 2.Notes on reading electrical diagrams

   

1. Learning to master a certain degree of basic knowledge of electronics, electrical technology, to understand the performance of various types of electrical equipment, the principle of operation, and clear about the contact action before and after the change in the state of the relationship.

2. Have a certain understanding of the common common typical circuits, such as over-current, under-voltage, overload, control, signaling circuits, the working principle and sequence of action.

3. Familiar with the national unified provisions of the graphic symbols of electrical equipment, text symbols, digital symbols, circuit numbering provisions of the general rules and related national standards. Understand the common commonly used peripheral electrical graphic symbols, text symbols, digital symbols, circuit number and the International Electrotechnical Commission (IEC) provides for the universal symbols and physical symbols (relevant information is attached).4. Understand the basic method of drawing the secondary circuit diagram. Electrical diagrams in the primary circuit with a thick solid line, the secondary circuit with a thin solid line drawn. Primary circuit drawn on the left side of the drawing, the secondary circuit drawn on the right side of the drawing. Draw the AC circuit first from top to bottom, and then draw the DC circuit. When different parts of the same appliance (e.g. coil, contact) are not drawn together, use the same symbol to label. For the same appliance in different circuits, label the numbers after the same symbols to distinguish them.

5. Switch and contact positions in the circuit are drawn in the 'usual state'. The so-called 'normal state' refers to the switch, relay coil in the absence of current and no external force when the contact state. Usually said that the dynamic closing, dynamic breaking contacts are referred to switching appliances in the coil without electricity, no external force when they are open or closed, once the power or external force when the contact state and change.

3.Methods of reading electrical diagrams


1. Carefully read the equipment manuals, operating manuals, to understand the mode of action of the equipment, the sequence, the role of the relevant equipment components in the circuit.

2. Against the drawings and drawings illustrate the general understanding of the structure of the electrical system, and combined with the contents of the main title of the whole drawing expressed the type of circuit, nature, role of a clearer understanding.

3. Read the system schematic drawings should first look at the drawing instructions. Combined with the description of the content of the drawings, and then understand the circuit system of the general situation, the composition of the components of the action sequence and control mode, for the reading of the detailed circuit schematic to make the necessary preparations.

4. reading centralized, expanded circuit diagrams in line with the first look at the primary circuit, and then look at the secondary circuit, the first after the order of AC DC, from top to bottom, from left to right, the principle of progressive order, look at the various circuits, and the status of the circuit equipment components and the control of the main circuits, to fully analyze the working principle of the entire electrical system to understand the 5. reading the installation of wiring diagrams should be compared with the electrical schematic diagram, the first primary circuit, and then the secondary circuit sequence of knowledge. Primary circuit, and then secondary circuit reading order. Read the installation wiring diagram should be combined with the circuit schematic detailed understanding of the significance of the terminal signs, circuit symbols. The primary circuit should be read from the power supply side in turn, to understand the line connection and direction. Until the end of the power equipment. The secondary circuit should be read from one end of the power supply until the other end of the power supply. Wiring diagrams of all the same number of wires. In principle, can be connected together.