4 - uses higher rating than maximum output offsetting increased cost by lower heat dissipation rate

Underfloor or underground transformer design which is expected to be loaded for an output of up to 250 KVA. The rating of the transformer installed will be higher than is necessary for the required output. This produces an increases in the cost of the foundation due to the increased dimensions. This extra cost will be less than that for a transformer operating at maximum rating due to the extra provisions necessary for conducting the heat dissipated away from the unit. The transformer is installed in a thin corrosion protected stell or glass fibre reinforced container. It is open at the top and is cooled by natural drainage via a cover grill.