Electrical control devices are also called electrical control equipment. Electrical control devices play the role of electric energy control, protection, measurement, conversion and distribution in the automation system. With the continuous development of control technology, high and low voltage electrical component technology, electrical automation technology and computer software/hardware technology, electrical control devices are also developing in the direction of digitization.
In order to ensure the reliable and safe operation of the controlled equipment, many auxiliary electrical equipment are needed to serve it. The combination of several electrical components and components that can realize a certain control function is called a control loop. Electrical control devices are generally divided into a primary control loop and a secondary control loop. Different controlled devices have different control loops. High-voltage electrical equipment and low-voltage electrical equipment have different control methods. These devices mainly have the following functions:
Automatic control refers to the use of electrical control equipment to make the controlled object or process automatically run according to a predetermined rule without anyone participating. For example, the volume of high-voltage and high-current switchgear is very large, and the operating system is generally used to control the opening and closing, especially when the device fails and the switch needs to automatically cut off the circuit.
Electrical control devices and lines will inevitably fail during operation, and the controlled equipment will inevitably have some problems. This requires a set of safety protection devices that detect these fault signals and automatically adjust equipment and lines (disconnect, switch, etc.) to ensure the safety of personnel and equipment.
The signal of the monitoring device can only qualitatively indicate the working status of the equipment (point or power failure). If you want to know the working status of the electrical equipment quantitatively, you also need a variety of instrument measuring equipment to measure various parameters of the circuit, such as voltage, current, frequency, power, etc.
In the operation and monitoring of electrical control devices, most of the traditional operating components, control electronics, instruments and signals can be replaced by computer control systems and electronic components, but there are still certain applications in small equipment and local control circuits. These are the basis for the circuit to realize the automatic control of the microcomputer.