What Are the Different Types of Electrical Wiring?

The main electrical wiring mainly refers to a circuit for transmitting electrical energy that is designed to meet the predetermined power transmission and operation requirements in power plants, substations, and power systems, and indicates the interconnection relationship between high-voltage electrical equipment. The electrical main wiring is a power transmission and distribution circuit consisting of the power supply incoming and outgoing wires as the basic link and the bus as the intermediate link ^[1] .

The high-voltage electrical equipment in the circuit includes generators, transformers, busbars,

The main electrical wiring should meet the following requirements:

(There are a

The main electrical wiring should meet the following basic requirements:

The main electrical connection of traction substations and railway substations should take into account the power supply incoming line conditions (with or without passing through), the importance of the load, the capacity and number of main transformers, the number of incoming and outgoing line circuits, the backup mode of the circuit breaker, The electrical equipment characteristics and other conditions are determined, and they have corresponding safety and reliability, flexible operation and economy.

Traction substations with first-level electric loads, railway substations that supply first-level electric loads such as transportation, production and safety and sanitation, and urban rail transit step-down substations (see electric loads and electric traction loads) should have two The power supply lines of the circuits are independent of each other. Each power supply line should be able to ensure the power supply to the entire load. Railway transformers and power distribution stations that do not have a first-level electric load should have a reliable line power supply. If possible, a two-line power supply line should be installed.

The number and capacity of the main transformers can meet the needs of the power supply load during the planning period, and can meet the needs of the power supply load when the transformer fails or is overhauled. In three-phase AC traction substations and railway substations, when a third-level voltage occurs and the load on the medium or low voltage side exceeds 15% of the rated capacity of the transformer, a three-winding transformer should usually be used as the main transformer.

According to the requirements of the local reactive power balance of the power system, the parallel traction substation and railway substation and power distribution are required to install parallel capacitor compensation equipment and corresponding main wiring power distribution units. In order to improve the harmonic content injected into the power system, the traction voltage-side busbar of the AC traction substation also needs to consider the connection of a reactive and harmonic integrated parallel compensation device circuit (see Parallel Integrated Compensation Device). For DC mains electrified railways, in order to reduce the impact of the DC 12-phase ripple voltage traction network load on the parallel communication lines along the line, a parallel filter circuit of 550 Hz, 650 Hz and other harmonics should be installed between the DC positive and negative buses of the traction substation. .

The voltage level of incoming and outgoing lines of the power supply, the number of circuits, the standby mode of the circuit breaker, and the maintenance cycle have a significant impact on the selection of the main electrical wiring form. When the power supply line of AC and DC traction substations with a voltage of 35 kV 220 kV is two circuits, the main wiring of double T-shaped branch wiring or bridge wiring should be used. When the input (out) line does not exceed four circuits or more In this case, the main wiring of a single bus or a segmented single bus can be used; when the incoming (out) line is four circuits or more, the main wiring of a segmented single line with a bypass bus should be used. For 6kV ~ 10kV railway substations and power distribution stations with two power sources running in parallel, single bus connection with circuit breaker section should be adopted; when the power supply line is one main and one backup, the section switch can be an isolation switch. Railway (station, section) power stations without local power supply, generally with installed capacity below 2 000 kV · A, and rated voltage of 400 V or 6.3 kV. The main electrical wiring should be a single bus or a single bus divided by a disconnect wiring.

The electrical wiring form of the traction load side of AC and DC traction substations should be based on the type and quantity of the main transformer (single-phase, three-phase or other), the type of circuit breaker or DC fast switch and backup method, the number of feeders and the annual transportation of the line. Volume or passenger factors. Generally, single-bus section wiring should be used. When the number of feeders is more than four circuits, single-bus section wiring with bypass bus should be used.