An MV/HV electrical enclosure or dedicated transformer room is designed to house critical electrical equipment while integrating equipment dimensions, access, maintenance, environmental and safety constraints. Depending on the installation, this may include power transformers, MV switchgear and associated auxiliary systems.
What is the enclosure designed to achieve?
Risk separation and fire considerations
The room layout must account for the hazards associated with the installed equipment. For oil-filled transformers, fire behaviour, oil containment and separation from adjacent areas are important design inputs. Internal-arc behaviour and pressure effects must be assessed using the requirements applicable to the actual equipment and project.
Mechanical and environmental protection
The enclosure protects equipment from relevant external conditions and provides a controlled installation environment. Noise, ventilation, cooling and environmental constraints may also influence the building design.
Personnel, operation and maintenance
Equipment is not designed only to fit inside the room. Engineers must consider operating access, maintenance clearances, removal routes and safe intervention around the equipment throughout its service life.
Key pre-design checks
- Equipment dimensions and mass: check the complete equipment envelope and structural loads.
- Access and handling: verify doors, openings, lifting arrangements and the route used to bring equipment into or out of the building.
- Maintenance clearances: preserve the working space required by the equipment and project requirements.
- Heat dissipation: establish equipment losses and coordinate ventilation or cooling requirements.
- Oil containment: for oil-filled equipment, define containment from the actual oil volume and applicable requirements.
- Interfaces: coordinate civil works, structure, HVAC, fire protection, cable routes and auxiliary systems.
Standards and project requirements
The French version of this article refers to French installation requirements. For an international project, do not transpose a French standard automatically. Determine the country, voltage level, applicable IEC or national standards, utility requirements and project specifications before validating the design.
Engineering takeaway: room dimensions are an output of equipment, operation, maintenance, safety and multidisciplinary interfaces—not simply the equipment footprint.