Analysis of the method of drawing the electric secondary map

1. Overview The current secondary design of 110kV and below substation is generally based on microcomputer-based hierarchical distributed integrated automation equipment. The principle is basically the same as that of conventional electromagnetic electric secondary protection. The text and graphic symbols used in design and installation are basically the same. Basically consistent, but there are also differences, which requires designers to be familiar with the micro-machine and conventional electrical secondary protection principles, understand the design ideas of the micro-machine protection manufacturer, so that the selected design of the engineering design is always reasonable. , correct, leading position.
The secondary part of the electrical system is attached to the primary part of the substation (primary equipment), which is an effective way to control, operate, monitor and protect the primary equipment. Therefore, it is an important part of the substation.

2. Secondary diagram of integrated automation system of substation
2.1 The text and graphic symbols of the electrical quadratic diagram To understand and master the drawings of the electrical secondary part, firstly, the words, numbers and graphic symbols represented in the secondary circuit should be mastered, and the differences between the old and new symbols, illustrations and numbers should be compared. To lay the foundation for further understanding. The old and new symbols are shown in Table 1.

The second is to understand the principle of electrical secondary protection, such as: circuit breaker control, main transformer protection, line protection, power capacitor protection, distance protection, bus protection, central signal and DC operating power supply parts.
Conventional protection, whether line protection or transformer protection, is divided into a control screen and a protection screen for design, and its signal device is set on the central signal screen. The microcomputer integrated automatic protection device integrates the functions of protection, control, measurement and signal, and adopts independent units. It can switch between Chinese and English menus through liquid crystal display. The information is detailed and intuitive, easy to operate and debug, and passed the industrial-grade total network cable group. Network, can directly communicate with the computer monitoring or protection management network.
2.2 Matters needing attention in the map The micro-machine type integrated automatic protection device of the substation is generally composed of line protection measurement and control, transformer protection measurement and control, capacitor protection measurement and control, public part, electrical metering, high-frequency DC power supply, and microcomputer monitoring.
In the first step, you should first understand the drawings and distinguish the roles and connections of each individual part to see if the drawings are complete. Then, for the independent control part of the layout, AC voltage, current loop, DC control, protection monitoring, signal Loops, rear panel terminals, etc. are performed one by one to find the causal relationship between the loops; then read the full map in its entirety. You should also pay attention to the following points when you are aware of the drawings:
1Understand the overview and working principle of the primary circuit structure related to the electrical secondary circuit;
2 understand the technical requirements and tasks to be achieved in the electrical secondary circuit;
3 understand the basic structure and performance of industrial computer;
4 should understand and master the technical performance and working principle of each unit of microcomputer protection;
5Familiar with the operating mechanism principle of the circuit breaker, technical parameters of the closing and tripping circuit;
6Understand the structural principle of primary electrical equipment such as transformer main transformer gas, temperature, on-load voltage regulation control and isolation switch, circuit breaker anti-misoperation;
7 Integrated automation system networking and communication protocols.

3. Selection of signal and closing circuit cable The cable selection of the electrical secondary circuit of the substation should follow the following principles:
1 The control cable is generally armored with rubber insulated copper core cable or armored PVC insulated copper core cable. The cross section of the copper core cable should be no less than 1.5mm2. When the cable has a long core number of 6 cores or more and a section of less than 4 mm2, a suitable spare core should be left.
2 The cross section of the current and voltage circuit should be no less than 2.5mm2. The signal cable is typically 1.5mm2.
3 The selection of the closing cable should be based on the closing current, voltage, power supply distance, mechanical strength, etc. of the circuit breaker.
Such as: ZW1-10 vacuum high-voltage switch with CT-type elastic mechanism voltage AC and DC 220V, AC closing current is less than 5A, DC closing current is less than 2.5A, cable can be PVC insulated copper core power cable VV22-2 ×1.5 to 2×2.5 type.
Such as: DW14-35 oil circuit breaker with CD11-X electromagnetic operating mechanism, closing current 127A, voltage DC 220V, cable can be PVC insulated copper core power cable VV22-2 × 16 ~ 2 × 35 type.
4 Microcomputer integrated automation screen network connection uses shielded wiring.

4. Conclusion Only by mastering the electrical secondary text, graphic symbols, microcomputer protection and conventional protection principles of the substation, apply it to the whole process of drawing pictures, constantly sum up experience, and study new theory and new knowledge in order to correctly master the synthesis. Automated substation electrical secondary part drawings.

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