Electrical control systems are generally referred to as secondary control circuits for electrical equipment. Different equipment has different control circuits, and the control methods for high-voltage electrical equipment and low-voltage electrical equipment also differ. Specifically, an electrical control system is a combination of several electrical components used to control one or more objects, thereby ensuring the safe and reliable operation of the controlled equipment.
To ensure the reliable and safe operation of primary equipment, numerous auxiliary electrical devices are required. A combination of several electrical components capable of performing a specific control function is called a control circuit or secondary circuit. These devices must have the following functions:
1. Automatic control function
High-voltage and high-current switching equipment is very large in size. It generally uses an operating system to control the opening and closing of the circuit. Especially when the equipment fails, the switch needs to automatically cut off the circuit. There needs to be a set of automatic control electrical operating equipment to automatically control the power supply equipment.
2. Protection Functions
Electrical equipment and lines may malfunction during operation, and the current (or voltage) may exceed the allowable range and limits of the equipment and lines. This requires a set of protection equipment to detect these fault signals and automatically adjust (disconnect, switch, etc.) the equipment and lines.
3. Monitoring function
Electricity is invisible to the naked eye. Whether a device is powered on or off cannot be determined from its appearance. Therefore, it is necessary to set up various audio-visual signals, such as lights and sounds, to monitor the electrical system of the device.
4. Measurement function
Light and sound signals can only qualitatively indicate the working status of equipment (power on or off). If you want to quantitatively know the working status of electrical equipment, you also need various instruments and measuring devices to measure various parameters of the circuit, such as voltage, current, frequency and power.
In equipment operation and monitoring, traditional operating components, control electrical appliances, instruments, and signaling devices can mostly be replaced by computer control systems and electronic components. However, they still have a certain range of applications in small equipment and circuits for localized control. These are the foundations for circuits to realize microcomputer-based automated control.
