Electrical main functions
In order to ensure the reliability and safety of primary equipment operation, many auxiliary electrical equipment are needed to serve it. The combination of several electrical components capable of achieving a certain control function is called a control circuit or a secondary circuit. These devices must have the following features:
(1) Automatic control function. The volume of high-voltage and high-current switching equipment is very large. Generally, operating systems are used to control opening and closing. Especially when the equipment fails, the switch needs to automatically cut off the circuit. There must be a set of automatically controlled electrical operation equipment. Automatic control of power supply equipment.
(2) Protection function. Electrical equipment and circuits will fail during operation, and the current (or voltage) will exceed the range and limits of the equipment and circuits allowed to work. This requires a set of signals to detect these faults and automatically adjust the equipment and circuits (disconnect, Switching, etc.).
(3) Monitoring function. Electricity is invisible to the eyes. Whether a device is powered on or off cannot be distinguished from the outside. This requires the installation of various audio-visual signals, such as lights and sounds, to electrically monitor the primary equipment.
(4) Measurement function. Light and sound signals can only qualitatively indicate the working status of the equipment (powered or off). If you want to know the working condition of electrical equipment quantitatively, you also need to have a variety of instrument measuring equipment, measuring various parameters of the circuit, such as voltage , Current, frequency and power.
In the operation and monitoring of equipment, most of the traditional operating components, control appliances, instruments and signals can be replaced by computer control systems and electronic components, but there is still a certain scope of application in small equipment and local local control circuits . This is also the basis for the circuit to achieve microcomputer automation control.