Do You Understand the Difference Between American-style Box Transformers and European-style Box Transformers and their Applicable Places?

03-11 2025 | By:

American-style box transformers, also known as American prefabricated cabins, are a type of substation equipment that integrates high-voltage switchgear and transformers and other equipment.It usually uses load switches and current-limiting fuses as power switches, and has the advantages of simple structure, easy operation, small size, and small footprint.
In contrast, European-style box transformers are a type of substation equipment that separates high-voltage switchgear and transformers and other equipment. It usually consists of a transformer, a high-voltage switchgear, and a low-voltage switchgear, and each device is connected to each other through cables or other transmission media.
01Differences between Padmount Liquid Filled Transformers and European-style box transformers
1. Pad Mounted Distribution Transformers:
(1) Wiring form of box transformers
One or two 10KV incoming lines; a single transformer, the capacity is generally selected to be 500KVA~800KVA; 4~6 low-voltage outgoing cables.
(2) Main components of the box transformer
It consists of transformer, 10KV ring network switch, 10KV cable plug, low voltage pile head box and other main components. It has the advantages of small size, low cost and easy installation.
(3) Advantages and disadvantages of American box transformer
1) Advantages: small size, small footprint, easy to place, easy to disguise, and easy to coordinate with the environment of the community. It can shorten the length of low voltage cables, reduce line losses, and reduce the cost of power supply accessories.
2) Disadvantages: Low power supply reliability; no electric mechanism, unable to add distribution automation device; no capacitor device, not conducive to reducing line loss; higher noise than type III and V stations, because type III and V stations place transformers indoors to play a role in sound insulation; in addition, the concentrated electromagnetic radiation of type III and V stations is decomposed into multiple points of radiation; due to the different civil engineering foundations of box transformers of different capacities, it is inconvenient to increase the capacity of box transformers; when the box transformer is overloaded or the user increases the capacity, the civil engineering needs to be rebuilt, there will be a long power outage time, increasing the difficulty of the project.

2. European box transformer: (1) Wiring form of box transformer a. Single distribution transformer form one or two 10KV incoming lines; single transformer capacity is generally 500KVA~800KVA; low-voltage outgoing cables are generally 4~6 lines. b. Two distribution transformers: one or two 10KV incoming lines; two transformers, each with a capacity of 500KVA~800KKVA; low-voltage outgoing cables are generally 8~12 lines.
(2) Main components of box transformers
It consists of transformers, 10KV ring network switch cabinets, low-voltage capacitors, low-voltage switches and other main components, which is equivalent to compactly installing the equipment of type III stations in a metal box, making type III stations miniaturized. The volume of European box transformers is higher and larger than that of American box transformers, and the cost is also higher than that of Three-phase pad-mounted transformers.
(3) Advantages and disadvantages of European box transformers
1) Advantages: Noise is equivalent to that of type III stations and type I stations; radiation is lower than that of American box transformers, because the transformer of European box transformers is placed in a metal box to play a shielding role; distribution automation can be set up, which not only has the advantages of type III stations and type I stations, but also has the main advantages of American box transformers.

2) Disadvantages: Large size, not conducive to installation, and has a certain impact on the environmental layout of the community; 02 Applicable places of American box transformers and European box transformers Due to the different structures of the box transformers, the places of use are also different, and the power supply networks are also different. Because the structures of Pad-mounted transformer and European box transformers are different and the reliability is different, the applicable occasions are also different. When the capacity of the American box transformer is selected to be smaller and the building area of ​​the community is larger, the box transformers used will increase a lot, thereby increasing the number of branch load points on the overhead line; when reducing the branch load points of the overhead line, the number of box transformers must be increased in series, making the network structure weak. To overcome the problem of weak network structure caused by small-capacity box transformers, it is best to use a ring network station to solve it.

1. Applicable places of American box transformers In view of the structural characteristics and advantages and disadvantages of American box transformers, American box transformers are suitable for the power supply of multi-story residential buildings and other unimportant buildings with relatively low power supply requirements. According to our actual use, the American box transformer is fully applicable to the power supply needs of multi-story residential buildings after being equipped with a small ring network switch station. Because even if the box transformer fails, the impact on residents is not great, but it is not suitable for small and high-rise buildings.
2. Applicable places for European box transformers
European box transformers are suitable for multi-story residential buildings, small and high-rise buildings, high-rise buildings and other important buildings.

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