Prefabricated substations can be divided into two types: Standard and compact. Standard prefabricated substations include models ZBW and XWB, while compact prefabricated substations include models ZB1-336 and GE. 10kV distribution equipment in prefabricated substations does not use circuit breakers; commonly used models include FN5-10 or FN7-10 load switches with fuses and ring network power supply devices, connected to the high-voltage end of the transformer from a nearby overhead line. Based on different product structures and components, they are typically divided into European-style and American-style prefabricated substations.
ZBW-type Prefabricated Substation: The ZBW-10/0.4kV outdoor combined substation is a prefabricated complete set of power distribution equipment consisting of a high-voltage compartment, a transformer compartment, and a low-voltage compartment. It is suitable for ring network, double-line, and terminal power supply methods, and the three methods are highly interchangeable. The incoming line uses cables. The high-voltage compartment features a fully reliable, compact design with comprehensive anti-misoperation interlocking functions, ensuring high reliability and convenient operation and maintenance. It is compatible with terminal load switches, air ring main units, and SF6 ring main units. Satons transformers can be oil-immersed or dry-type. The transformer room is temperature-controlled and can utilize natural ventilation or forced ventilation from the top. The low-voltage compartment is equipped with metering and reactive power compensation, and secondary circuits and the number of outgoing lines can be designed according to user needs to meet diverse requirements.
GE Prefabricated Substations
The difference between GE prefabricated substations and domestic modular prefabricated substations lies in their development based on transformers. GE prefabricated substations simplify the structure of the transformer core, high-voltage load switch, fuses, and other equipment, placing them all within a single oil-filled iron box. They are small in size, compact in structure, and occupy only about one-third the floor space of domestic prefabricated substations of the same capacity. The fully sealed, fully insulated structure eliminates the need for insulation distance, reliably ensuring personal safety. High-voltage cables are connected to bushings with good insulation performance, and the bushings are connected to elbow-type cable plugs, sealing the live parts within the insulation. Elbow-type cable plugs can be plugged and unplugged under full transformer load, acting as a load switch. There are many types available, and careful selection is necessary for specific applications. Wall mounts are welded to the enclosure to secure the support-type insulating bushing joints. When the elbow-type cable plug is unplugged, it can be inserted into the support-type bushing joint.
Classifications of European and American Prefabricated Substations:
Modular Substation: Modular substations house high- and low-voltage switchgear and transformers within a metal enclosure, with an operating corridor between the high- and low-voltage distribution units. This type of prefabricated substation is relatively large and is less commonly used now.
Combined Unit Substation: Combined unit substations do not use existing switchgear; instead, the high- and low-voltage control and protection electrical equipment are directly integrated into the enclosure, making it a single unit. Because the overall design is maintenance-free, an operating corridor is not needed inside the enclosure. This reduces the size of the prefabricated substation. This type is the European-style prefabricated substation and is widely used.
Integrated Substation: Integrated substations are also known as American-style box-type substations. They are built by simplifying high and low voltage control and protection devices, integrating the high and low voltage distribution equipment with the transformer body into a single unit within the transformer tank. This type of box-type substation is smaller, with a volume approximately the same as a standard oil-immersed transformer of the same capacity. It is only about 1/3 the size of a European-style box-type substation of the same capacity.
Combined, Box-type Substations
6⁻¹/0.4(0.7)kV Prefabricated (Combined, Box-type) Substation
Mining Combined (Box-type) Substation
6⁻¹/0.4kV Prefabricated (Combined, Box-type) Substation
35/6⁻¹kV Combined (Box-type) Substation
The incoming line can be either a cable or an overhead insulated wire, chosen arbitrarily according to the usage environment and different purposes. When used as a public box-type substation, the number of low-voltage outgoing lines depends on the transformer capacity, generally not exceeding 4 lines, and at most 6 lines. Alternatively, a single main outgoing line can be used to supply power to a nearby distribution room. When a prefabricated substation is used as an independent user, a single circuit power supply can be adopted.