A Compact Secondary Substation (CSS) is a type-tested, pre-fabricated substation comprising an enclosure that integrates medium voltage (MV) switchgear, distribution transformers, low voltage (LV) switchboards, connections, and auxiliary equipment ? used for energy transformation in secondary distribution networks. It replaces conventional substation arrangements by consolidating a Vacuum Circuit Breaker (VCB) or Load Break Switch (LBS), transformer compartment housing dry-type or oil-cooled transformers, and an LV compartment with ACB, MCCB, and SFU ? all within three dedicated sections. With a protection degree reaching IP55, CSS units can be installed outdoors while occupying minimal area, supporting voltage ratings from 11 kV to 40.5 kV. Factory pre-tested as a single-piece delivery, CSS ensures faster engineering timelines, internally arc-tested safety for personnel, and an enclosed environment that protects all critical equipment. Ideal for high-density urban locations where space and safety are priorities, CSS significantly reduces inter-equipment cabling costs and minimises electrical failure risks