Occasionally submersible transformers are manufactured in powers from 15 kVA to 333 kVA single-phase and from 45 kVA to 1000 kVA three-phase, with voltages up to 34.5 kV (BIL 150kV), complying with the NTC standards (Occasionally Submersible Transformer), ANSI and EDC (Submersible transformer).

They are used in underground distribution circuits susceptible to corrosive environments and temporary flooding.

They are of the RADIAL or MESH type, depending on customer requirements and use high voltage elastomeric elements for their connection for underground applications that allow high safety and reliability during operation, such as bayonet assemblies of vertical position, canister type fuse elements, long well type bushings that allow them to be immersed in the oil, vertical position under load ON-OFF switch, oil level, additionally all accessories required by the customer are installed.

The TANKS are made from resistant to corrosion materials and commonly manufactured in stainless steel sheet 304, in which case they are applied a simple layer of finishing paint to give presentation, or otherwise, in iron sheets 8 and 12 mm thick, and finally coated with Epoxy type paints with tar components.

As a rule, all accessories are located on the top of the transformer, allowing access to them through the top of the vault where they are usually installed. Said lid can be made welded or bolted, according to the customer's requirements.

Depending on the power, a vertical radiation system with fins is used, which allows a more compact construction of the tank, in radiation panels with radiating elements made of 8 mm sheets.