With the continuous development of social economy, China has gradually entered the era of industrialization. According to the requirements of the four modernizations, the mainstream direction of industrial development in the future is to achieve modernization.
The realization of industrial modernization must be supported by electrical automation technology. Programmable controller is an advanced controller, which is widely used in the field of electrical automation. Therefore, it is necessary to study the programmable controller. This article will combine the working principle and working characteristics of PLC, analyze and study the specific application method of PLC in electrical control, hoping to be helpful to the development of electrical automation control technology. The programmable controller has the characteristics of high control level and is widely used in the industrial field. Programmable controllers are needed in both mechanical manufacturing and industrial automation control. The appearance of programmable controller greatly improves the level of industrial control technology and promotes the further development of industry. This paper will start with the introduction of programmable controllers, introduce the specific application scope of programmable controllers in electrical control and their advantages compared with other controllers, cite specific application examples of programmable controllers in the field of electrical control, and analyze the future development direction of programmable controllers. Programmable controller is a general controller based on computer technology. In the process of industrial practice, we usually call it PLC. The so-called programmable controller refers to the use of computer programming technology to control the operation of equipment, so as to achieve the purpose of automatic control of equipment. In recent years, with the continuous development of computer technology and control technology, the function of programmable controller has become more and more powerful. When the programmable controller came into being, it had only a few simple functions, such as logical operation function, sequence control function and so on.
Now, the function of programmable controller is far beyond the expectation at that time. It not only can realize the function of home automation application, but also can be applied in many different fields, such as commerce, industry, public utilities and so on. It provides great convenience for people’s life and work. Before there was no programmable controller, relays and contactors were mostly used to control the operation in the industrial field. These two control modes are also helpful to the development of industry. However, these two control methods have some disadvantages, which are far from the efficiency of programmable controllers. Therefore, when the programmable controller came into being, it replaced the above two control modes in a relatively short time and became the most frequently used control equipment in the industrial field. Compared with other control devices, programmable controller has significant advantages. First of all, programmable controllers need programming operation, thermostatic element but the programming process is relatively simple, operators can master the programming method through simple training. Moreover, the installation and later maintenance of the programmable controller are more convenient. If need to upgrade the system or need to re-edit the system takes a relatively short time, it will not affect the normal control work. Secondly, the programmable controller has strong anti-interference ability, good stability and high reliability in the working process. In the process of work, the power consumption is relatively small. Finally, the volume of the programmable controller is small and the movement is convenient. Programmable controller is widely used in electrical control. Generally speaking, the application of programmable controller in electrical control can be divided into the following categories. First, it is used in the field of switch control.
Before the use of programmable controller, relays are usually used as switching control devices. But because the programmable controller has two control modes, logic control and sequential control, it can achieve the goal of controlling multiple devices at the same time. Therefore, in the field of switch control, PLC has gradually obtained the relay; second, it is applied in the field of decentralized control.
The so-called decentralized control means that the programmable controller is installed in each control object, so that the signal can be transmitted through the programmable controller, so as to achieve the purpose of joint control of all control objects; third, the application in the field of analog control. The application of programmable controller in analog control mainly controls the flow rate and liquid level change, etc. Fourth, it is applied in the field of centralized control. Centralized control and decentralized control have the same point, that is to say, programmable controller can be used to monitor all equipment, but centralized control only uses one programmable controller to centralize the monitoring of equipment. This paper mainly takes the application of programmable controller in the field of switching control as an example to analyze the advantages of programmable controller over relay and single-chip control.
Firstly, the disadvantage of relay application in switching control field is introduced. The one-time input cost of relay is relatively high, the energy consumption is relatively large in the process of use, and a single control mode is adopted, which makes it difficult to effectively control multiple devices, and the error rate is relatively high. Secondly, the disadvantage of MCU control in the field of switching control is introduced. The design process of single-chip computer is more complex, the programming is more difficult, and the scope of use is relatively small, so it can only be used in the production system of a single finished product. Finally, the advantages of programmable controller in switching control are introduced.
Programmable controllers can achieve the purpose of simultaneous control of multiple devices. The energy consumption is relatively low and the economic cost is relatively low in the use process. In the process of later use, the system can be edited and upgraded according to the need.
The most common application of programmable controller in the field of control is to control ordinary electrical equipment. Taking the automatic washing machine as an example, this paper introduces the specific application of PLC in electrical control. First, the main functions of the automatic washing machine are introduced, including washing, dewatering and other auxiliary functions, including water volume control and washing mode selection. The application of PLC in automatic washing machine is shown in Figure 1.
There are many applications in the programmable logic controller of the washing machine. These applications represent some specific functions, which are the programs that have been written by the washing machine manufacturer in the process of production. In the process of using, people only need to choose a specific program according to their needs. Programmable controllers perform a series of operations according to the program people choose. The first step is to close the motor and so on, then open the water inlet valve, and then control the motor to make it positive and negative. People will set the washing time before using, and when the washing time arrives, the programmable controller will automatically stop and enter the next step, namely dehydration. Before starting the dehydration process, other control processes such as alarm of dehydration imbalance will also be involved. The programmable controller will stop running automatically after completing the set number of dehydration tasks. With the continuous development of computer technology and control technology, the application scope of programmable controller will continue to expand, and the application in the life field will be more and more.
For example, programmable controllers can be applied to building lighting systems. This can not only achieve the purpose of real-time monitoring of the whole lighting system, but also reduce the energy consumption of building lighting system. In addition, programmable controller can also be applied to refrigerators, air conditioners and other household appliances, so as to achieve the purpose of automatic control of household appliances. In short, the emergence of programmable controllers is of great significance to the development of electrical control field and greatly improves the efficiency of electrical control.
In the future, with the continuous development of programmable controller, its application scope will become more and more extensive, and its automation will be greatly improved.