The electric power control system is generally called the secondary control loop of the electrical equipment. Different equipments have different control loops, and the control methods of the high voltage electrical equipment and the low voltage electrical equipment are also different.

 

The main function

In order to ensure the reliability and safety of the primary equipment operation, a number of auxiliary electrical equipments are required to serve, and a combination of several electrical components capable of realizing a certain control function is called a control loop or a secondary loop. These devices have the following features:

 

(1) Automatic control function. The volume of high-voltage and high-current switching devices is very large. Generally, the operating system is used to control the switching and closing. Especially when the device fails, the switch needs to automatically cut off the circuit, and there must be an automatic control device. Automatic control of power supply equipment.

 

(2) Protection function. Electrical equipment and lines will malfunction during operation, and the current (or voltage) will exceed the range and limits of equipment and line operation. This requires a set of detection of these fault signals and automatic adjustment of equipment and lines (disconnect, Switching devices, etc.).

 

(3) Monitoring function. Electricity is invisible to the eye. Whether a device is energized or de-energized cannot be distinguished from the outside. This requires setting various audio-visual signals, such as lighting and sound, to perform electrical monitoring on the primary device.

 

(4) Measurement function. The lighting and audible signals can only qualitatively indicate the working state of the equipment (with or without power). If you want to know the working condition of the electrical equipment quantitatively, you need to have various measuring instruments to measure various parameters of the line, such as voltage. , current, frequency and power size.

 

In the operation and monitoring of equipment, traditional operating components, control appliances, instruments and signals are mostly replaced by computer control systems and electronic components, but there are still some applications in small devices and locally controlled circuits. . This is also the basis for the circuit to achieve automatic control of the microcomputer.