From Electrical Installation Guide

Architecture = choice of a single-line diagram and technological solutions, from connection to the utility network through load power supply circuits.

Main MV/LV distribution = Level upstream of the architecture, from connection to the network utility through to LV distribution equipment on the site (MLVS – or equivalent).

MLVS – Main Low Voltage Switchboard = Main switchboard downstream of the MV/LV transformer, starting point of power distribution circuits in the installation

LV power distribution = intermediate level in the architecture, downstream of the main level through to the sub-distribution switchboards (spatial and functional distribution of electrical power in the circuits).

LV terminal distribution = Downstream level of the architecture, downstream of the sub-distribution switchboards through to the loads. This level of distribution is not dealt with in this guide.

Single-line diagram = general electrical schematic diagram to represent the main electrical equipment and their interconnection.

MV substation, transformation substation = Enclosures grouping together MV equipment and/or MV/LV transformers. These enclosures can be shared or separate, according to the site layout, or the equipment technology. In certain countries, the MV substation is assimilated with the delivery substation.

Technological solution = Resulting from the choice of technology for an installation sub-assembly, from among the different products and equipment proposed by the manufacturer.

Characteristics = Technical or environmental data relative to the installation, enabling the best-suited architecture to be selected.

Criteria = Parameters for assessing the installation, enabling selection of the architecture that is the best-suited to the needs of the customer.