The power system is an energy production and consumption system composed of power plants, transmission and distribution lines, power supply and distribution stations, and electricity consumption. Its function is to convert primary energy from nature into electricity through power generation devices, and then supply electricity to various users through transmission, transformation, and distribution. To achieve this function, the power system also has corresponding information and control systems at various stages and levels, which measure, regulate, control, protect, communicate, and schedule the production process of electricity to ensure that users receive safe and high-quality electricity.
The equipment department of the power system is divided into primary equipment and secondary equipment.
Primary equipment refers to electrical equipment directly used for production, transformation, transportation, diversion, distribution, and use of electrical energy, as well as high voltage control circuits (secondary equipment). The main components include: generator (motor), transformer, circuit breaker, isolation switch, automatic switch, contactor, knife switch, busbar, transmission line, power cable, reactor, etc. The primary circuit or primary wiring system refers to the electrical main circuit formed by the interconnection of primary equipment for power generation, transmission, distribution, or direct use in production.
Main functions of primary equipment:
1. Equipment for producing and converting electrical energy. For example, a generator that converts mechanical energy into electrical energy, a transformer that converts voltage, and a motor that converts electrical energy into mechanical energy.
2. Switching equipment for connecting and disconnecting circuits. Such as high and low voltage circuit breakers, load switches, fuses, isolation switches, contactors, magnetic starters, etc.
3. Protect electrical equipment. Reactors that limit short-circuit current, lightning arresters that protect against overvoltage, etc
4. Current carrying conductor. Such as soft and hard conductors and cables for transmitting electrical energy.
5. Grounding device.
In power production, 'primary' mainly refers to the 'main circuit', while 'secondary' is mainly used to control 'primary'. The use of "primary" to modify equipment is mainly to reflect that the equipment belongs to the main circuit or the voltage level of the equipment is higher than that of the secondary equipment.
Secondary equipment refers to low-voltage electrical equipment that monitors, controls, regulates, protects the operation of primary equipment, and provides operating conditions or production command signals for operation and maintenance personnel. Such as fuses, control switches, relays, control cables, etc. The electrical equipment that is connected by secondary equipment to monitor, control, regulate, and protect the primary equipment is called secondary equipment.
The secondary equipment mainly includes instruments, control and signal components, relay protection devices, operation, signal power supply circuits, control cables and connecting wires, signal components that emit sound, terminal blocks, and fuses.
Terminal blocks, as connectors, serve as a bridge between electrical equipment and wires, and can also transmit signals such as current and voltage, making it convenient for construction and maintenance of the power system. They can even be used as electrical switches. For decades, wiring terminals have been used in various electrical equipment to ensure the smooth operation of circuits.