In Europe, a bare transformer is rarely connected on its own: a prefabricated cabin is set down, ready to plug in. Here is what this compact substation is, what it contains, and why the format won.
A compact substation, also called a prefabricated cabin or package substation, is an integrated assembly, built and tested at the factory, that gathers in a single enclosure: the medium-voltage switchgear (cubicles / switches), the transformer, and the low-voltage board. It answers to IEC 62271-202, the standard specific to prefabricated substations; in France the installation of an MV delivery substation additionally falls under NF C 13-100.
On the ground it takes the form of a concrete or metal cabin, set down on a slab and connected, hence the "turnkey" label. It is exactly our MV substation.
European MV distribution largely runs in ring networks (rather than simple radial spurs). At each point of the ring you therefore need ring switchgear, typically a ring main unit (RMU), to enter and leave the loop and feed the transformer. The compact substation natively integrates that switchgear with the transformer and the LV board: it fits the architecture exactly.
Practical reasons pile on: urban density and integration requirements (a closed, discreet cabin rather than open-air equipment), reduced civil works and fast connection. It is a marked difference of habit from the North American model, organised more around the padmount transformer on radial networks.
The compact substation is not always the response: for a replacement in an existing room, or when the MV switchgear is already in place, a transformer alone is enough. The choice follows your existing infrastructure, which we frame together.
General overview; the exact configuration (switchgear, power, enclosure) is defined by your connection and your network operator's rules.
Yes, those are common names for the same equipment: a factory-assembled prefabricated substation integrating MV switchgear, transformer and LV board, under IEC 62271-202.
Because European MV distribution largely runs in ring networks, which call for ring switchgear (an RMU) at each substation. The prefabricated cabin natively integrates that switchgear with the transformer and the LV board, so it fits the architecture exactly.
Yes: the transformer inside can be oil-immersed (mineral oil or ester) or cast resin dry-type, chosen for the environment. Enclosure, ventilation and IP rating are matched to that choice.
Your connection and the network operator's rules: switchgear layout, metering, protections and enclosure are framed together with your design office and validated at quotation stage.